THESiS

This is to certify that the

thesis entitled

THE lrlASATCHIAN-BRIDGERIAN LAND MAMMAL AGE BOUNDARY (EARLY
T0 MIDDLE EOCENE) IN THE DESERTION POINT-LITTLE MUDDY AREA,

SOUTHWESTERN GREEN RIVER BASIN, WYOMING

presented by

JOHN-PAUL ZONNEVELD
has been accepted towards fulfillment

of the requirements for

MJSC. degree in GEOLOGY

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Date 1/7/99
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THE WASATCHIAN-BRIDGERIAN LAND MAMMAL AGE BOUNDARY
(EARLY TO MIDDLE EOCENE) IN THE DESERTION POINT-
LITTLE MUDDY AREA, SOUTHWESTERN GREEN RIVER BASIN, WYOMING

BY

John-Paul Zonneveld

A THESIS
Submitted to
Michigan State University
in partial fulfilment of the requirements
for the degree of

MASTER OF SCIENCE

Department of Geological Sciences

1994

ABSTRACT
THE WASATCHIAN-BRIDGERIAN LAND MAMMAL AGE BOUNDARY

(EARLY TO MIDDLE EOCENE) IN THE DESERTION POINT-
LITTLE MUDDY AREA, SOUTHWESTERN GREEN RIVER BASIN, WYOMING

BY

John-Paul Zonneveld

A relatively diverse vertebrate assemblage is described
from a continuous sedimentary sequence spanning the boundary
between the Wasatchian and Bridgerian North American Land-
Mammal Ages (early—middle Eocene). Two distinct faunas are
separated by approximately eighty meters of unfossiliferous
lacustrine sediments.

The Little Muddy local fauna is assigned to the
Lostcabinian (Wa7) based primarily on the presence of
ngbfiogherium.nonoagagium and the co-occurrence of Egthonxg
agggigggg,ygggg;gggg cf. Q. australotutug and.ggg;;g§ cf. Q.
fgggivorggg. For the first time, Igggciug grayyglligggg and
Aggggggxgiglwortmani are identified from the Lostcabinian of
the Green River Basin. The Desertion Point local fauna is
assigned to the earliest Bridgerian (Brl), based on the co-
occurrence of Palagosxops cf. g. fontinalig, Bxgachygg,
fig;ggg;g§g§, gmilggegtes mcgrewi, gotharctus robinggni,
gaggxg gartgri, and Whghakigs ingiggig.

This is the first time the Wasatchian—Bridgerian
boundary has been delineated within the type area of these

North American Land Mammal Ages.

To my parents, Jacob and Nellie Zonneveld, for

their continued support (and patience).

iii

ACKNOWLEDGEMENTS

There are many people who deserve thanks for their part
in this thesis. First and foremost I wish to thank Dr. J.
Alan Holman. His guidance and friendship helped
immeasurably in the completion of this study. I wish to
thank the members of my committee, Drs. William S. Bartels,
Richard Seltin, and Ralph Taggart, whose council and
assistance have been invaluable in the preparation of this
thesis.

This study is part of an ongoing project investigating
the vertebrate paleontology of the earliest Bridgerian in
southwestern Wyoming. Drs. Gregg F. Gunnell and William S.
Bartels deserve special recognition for allowing me to be a
part of this project, for their advice on matters geological
and paleontological, and for their years of friendship.

I am grateful to Dr. William Sanders for his expert
preparation of many of the fossils, to Dr. Gregg Gunnell for
access to fossil vertebrates at the University of Michigan,
to Ms. Paula Lomnicki, and Ms Teresa Petersen for the
illustrations included in this manuscript, to Mr. John
Williams, my field assistant during the 1992 field season,
and to the many collectors who survived fossil collecting in
the "abiotic zone". Drs. Beth Strasser, Con Childress, and

iv

 

George Junne provided invaluable insight during our many
field seasons together.

Drs. Holman, Gunnell, Bartels, Seltin, and Taggart
reviewed and greatly improved this manuscript. Elizabeth
Rachman and Ken Ford are thanked for proofreading large
portions of this thesis. Peter and Ria Bulthuis are thanked
for their constant encouragement in pursuing my interests in
geology and paleontology.

This project was supported by Geological Society of
America grant 5097-92 and the Lucille Drake Pringle Endowed
Fellowship (Department of Geology, Michigan State
University) to John-Paul Zonneveld, by National Geographic
Society and University of Michigan, Museum of Paleontology
to Gregg F. Gunnell, and several Pew Foundation and Hewlett—

Mellon Foundation Grants to William S. Bartels.

TABLE OF CONTENTS

Page
LIST OF TABLES ........................................... x
LIST OF FIGURES ........................................ xii
LIST OF PLATES ......................................... xiv
ABBREVIATIONS USED ...................................... XV
INTRODUCTION ............................................. 1
Location and Description ............................ 2
Materials and Methods ............................... 3
Previous Investigations ............................. 4
LITHOSTRATIGRAPHY ........................................ 8
Bridger Formation ................................... 8
Wasatch Formation .................................. 11
Green River Formation .............................. l4
FOSSIL VERTEBRATE LOCALITIES ............................ l6
FAUNAL LIST ............................................. 25
SYSTEMATIC PALEONTOLOGY ................................. 29
Kingdom Monera
Phylum Cyanophyta
Stromatolites ............................ 31
Kingdom.Animalia
Phylum Arthropoda
Class Crustacea
Subclass Ostracoda ......................... 33

vi

 

Phylum Mollusca
Class Gastropoda
Order Mesogastropoda
Family Viviparidae .................. 34

Family Pleuroceridae ................ 35

Order Pulmonata

Family Physidae ..................... 37
Family Planorbidae .................. 38
Order Stylommatophora
Family Urocoptidae .................. 39
Family Bulimulidae .................. 40
Class Pelecypoda .............................. 4O

Phylum Chordata
Class Osteichthyes
Order Lepisosteiformes
Family Lepisosteidae ................ 41

Order Amiiformes
Family Amiidae ...................... 44

Order Siluriformes
Family Ictaluridae .................. 45

Class Reptilia
Order Chelonia (Testudines)

Family Baenidae ..................... 46
Family Emydidae ..................... 48
Family Trionychidae ................. 53
Family Dermatemydidae ............... 54
Family Carettochelyidae ............. 56

Order Squamata
Suborder Sauria (Lacertilia)
Family Iguanidae .................... 58
Family Anguiidae .................... 59
Suborder Serpentes
Family Boidae ....................... 63

vii

 

Suborder Amphisbaenia .................. 65

Order Crocodilia

Family Alligatoridae ................ 67
Family Crocodylidae ................. 69
Family Pristichampsidae ............. 71

Class Mammalia
Infraclass Metatheria
Order Marsupialia
Family Didelphidae .................. 74

Infraclass Eutheria
Order Insectivora

Family Apatemyidae .................. 77
Family Pantolestidae ................ 77
Family Lepticidae ................... 78
Family Dormaaliidae ................. 81

Order Proprimates

Family Paromomyidae ................. 85

Family Microsyopidae ................ 86
Order Primates

Family Adapidae ..................... 93

Family Omomyidae ................... 104
Order Creodontidae

Family Hyaenodontidae .............. 111
Order Carnivora

Family Miacidae .................... 112

Family Viverravidae ................ 115

Order Condylartha
Family Meniscotheriidae ............ 118

Family Hyopsodontidae .............. 120

Order Taeniodonta
Family Stylinodontidae ............. 123

viii

 

Order Tillodonta

Family Esthonychidae ............... 125
Order Artiodactyla
Family Dichobunidae ................ 127
Order Perissodactyla
Family Equidae ..................... 130
Family Brontotheriidae ............. 135
Family Helaletidae ................. 139
Order Rodentia
Family Sciuravidae ................. 146
Family Paramyidae .................. 151
Order Incertae sedis
Family Metcheiromyidae ............. 156
Family Epoicotheriidae ............. 157
EOCENE BIOSTRATIGRAPHY ................................. 159
Wasatchian Land Mammal Age ........................ 160
Bridgerian Land Mammal Age ........................ 160
AGE AND CORRELATION OF THE LITTLE MUDDY-DESERTION
POINT FAUNAS ........................................... 163
Little Muddy Local Fauna .......................... 165
Desertion Point Local Fauna ....................... 170
STRUCTURAL AND SEDIMENTARY HISTORY ..................... 178
PALEOENVIRONMENTS AND PALEOECOLOGY ..................... 186
Paleobotany and General Paleoecology .............. 187
Paleoecology of the Little Muddy local fauna ...... 188

Paleoecology of the Desertion Point local fauna...191

DISCUSSION AND SUMMARY ................................. 194

CONCLUSION ............................................. 203

APPENDIX ............................................... 205

LITERATURE CITED ............. I ......................... 233
1X

Table
Table
Table
Table
Table
Table
Table
Table
Table
Table
Table

Table

Table

Table

Table

4a.

4b.

10.

11.

12.

13.

14.

- the Little Muddy-Desertion Point area.

LIST OF TABLES

Measurements (in mm.) of Marsupialia .......... 76
Measurements (in mm.) of Insectivora .......... 83
Measurements (in mm.) of Proprimates .......... 92
Measurements (in mm.) of Adapid Primates ..... 103
Measurements (in mm.) of Omomyid Primates....110
Measurements (in mm.) of Carnivora ........... 117
Measurements (in mm.) of Condylartha ......... 124
Measurements (in mm.) of Tillodontia ......... 127
Measurements (in mm.) of Artiodactyla ........ 129
Measurements (in mm.) of Perrisodactyla ...... 147
Measurements (in mm.) of Rodentia ............ 155
North American Early to Middle Eocene
Continental Biostratigraphy. Ma indicates
millions of years before present and is
approximate .................................. 162

Chronologic ranges of mammalian taxa within
The
lines indicate the known stratigraphic range
of each taxon, X's indicate the horizons
within the study area from which species have
been recovered, and ?'s denote questionable

occurrences .................................. 163
Faunal list of the Little Muddy local fauna..165
Faunal List of the Desertion Point local

fauna ........................................ 171

 

Table 15.

Table 16.

Percent composition of the Little Muddy local
fauna. The minimum number of individuals is
used in calculating the ordinal percentages.

The number in parentheses indicates the total
number of specimens .......................... 198

Percent composition of the Desertion Point

local fauna. The minimum number of

individuals is used in calculating the

ordinal percentages. The number in

parentheses indicates the total number of
specimens .................................... 199

xi

Figure

Figure

Figure

Figure

Figure

Figure

Figure

Figure

Figure

Figure

10.

LIST OF FIGURES

Map showing the Green River Basin of
southwestern Wyoming and surrounding
mountains ................................. 6

Location Map of study area ................ 7

Generalized stratigraphic column of the
Desertion Point-Little Muddy area ......... 9

Map of study area showing localities and
biostratigraphic zonations ............... 18

Epiplastra of Echmatggxs species from the
study area. A. g. yxomingensis

(UM 98717), B. E. sentaria (UM 101024)

C. E. gigollensis (UM 101153). Bars are
one millimeter in length ................. 52

Trunk vertebra of Calamagras primns (UM
101211). Bars are one millimeter in
length ................................... 66

Crocodilian teeth. A. Allogggthgggghug
(UM 100892). B. Diglocxgodon (UM 98577m).
C. Qrocodzlus affinis (UM 101012m). D.

ggiggiggggpggg vgrax (UM 98577m). Bars
are one millimeter in length ............. 73

Palagictgps bigusnig. A. Occlusal View
of /M2 (UM 101166) B. Buccal View of /M2

(UM 101166). Bars are one millimeter in
length ................................... 8O
Igggciug graybullianus. Occlusal view of
M2/ (UM 101154). Bar is one millimeter

in length ................................ 87

gaggius cf. Q. frugivorous. Occlusal view
of /M3 (UM 101166). Bar is one millimeter

in length ................................ 96

xii

Figure

Figure

Figure

Figure

Figure

Figure

Figure

Figure

11.

12.

l3.

14.

15.

16.

17.

18.

Notharctus robinsoni. Occlusal view of

/M3 (UM 98576). Bar is one millimeter in
length ................................... 96
Conelemur cf. g. australotutus. Occlusal
view of /M2 (UM 101009). Bar is one
millimeter in length ..................... 99

Omogxs carteri. Occlusal view of right
dentary with /M2 and /M3 (UM 101038).
Bar is one millimeter in length ......... 106

Anemornxsis near ;. wortmani. Occlusal

View of /M1 (UM 101159). Bar is one
millimeter in length .................... 106
Migcis latidens. Occlusal view of M1/

(UM 100028). Bar is one millimeter in
length .................................. 113

Lambdotherigg,nopoggacium. A. Occlusal
View of /P4 (UM 100891). B. Buccal View

of /P4 (UM 100891). Bar is one
millimeter in length .................... 137

§§1eneletes sp. indet. A. Occlusal view
of left dentary with /M2 and /M3

(UM 94913). B. Buccal view of left

dentary with /M2 and M/3 (UM 94913).

Bars are one millimeter in length ....... 142

Correlation chart of lithostratigraphy,
fossil vertebrate localities, faunal
levels, and biostratigraphy. DPLF

denotes Desertion Point local fauna,

LMLF denotes Little Muddy local fauna...18l

xiii

LIST OF PLATES

Plate I. Geologic map of Desertion Point—Little Muddy area,
southwestern Green River Basin, Wyoming.

Plate II. Correlation of measured stratigraphic sections

within the Eocene Wastch, Green River and Bridger
formations, Lincoln and Uinta counties, Wyoming.

xiv

USGS-

USNM-

YPM-

AP-

Tra-

LIST OF ABBREVIATIONS

Institutions:

Pratt Museum, Amherst College
American Museum of Natural History

University of Michigan, Museum of paleontology
United States Geological Survey

United States National Museum

University of Wyoming

Yale Peabody Museum

Measurements, Specimens and Localities:
anteroposterior Tr- transverse
transverse, anterior Trp— transverse, posterior

lower tooth X/— upper tooth

molar P— premolar

canine I- incisor

Bridger Basin *— measurement approximate

specimen included in miscellaneous box

 

 

INTRODUCTION

Hundreds of early and middle Eocene vertebrate fossil
localities have been reported from the Tertiary basins of
Wyoming, Colorado, New Mexico and Utah. In several of
these, continuous depositional sequences spanning the early—
middle Eocene boundary (Wasatchian—Bridgerian boundary) are
known. Extensive faunas from these sequences have been
reported in the Wind River and Huerfano basins (Guthrie,
1967; 1971; Robinson, 1966; Stucky, 1984a; 1984b) and less
comprehensive faunas are known from the Washakie and Bighorn
basins, (Gunnell g; al., 1992; Turnbull, 1978) and the
northeastern Green River Basin (West, 1969; 1970; 1973).

Although extensive faunas are known from southwestern
wyoming where the type areas of both the Wasatchian and
Bridgerian Land Mammal Ages are known (e.g. Gazin, 1952;
1962; Wood, 1966; Pledge, 1969; McGrew and Sullivan, 1970;
Gunnell and Bartels, in press), faunas spanning the
Wasatchian-Bridgerian (Lostcabinian-Gardnerbuttean subage)
boundary in this area have not been extensively reported.

A field research project was initiated by G.F. Gunnell
in 1989 to investigate early Bridgerian vertebrate

paleontology in the southwestern Green River Basin (Bridger

 

 

2

Basin). This field work not only tripled the previous
collection of early Bridgerian fossils from the Bridger
Basin (Gunnell and Bartels, in press), but, in 1992 a
locality was discovered at the extreme western margin of
this area, containing a small, but diagnostic, Wasatchian
assemblage in the La Barge Member of the Wasatch Formation.

Subsequent field work has shown that an essentially
continuous transitional depositional sequence exists between
the La Barge Member to the west through the lower Bridger
Formation to the east. This study documents the vertebrate
paleontology across the Wasatchian-Bridgerian boundary in
this sequence, and delineates for the first time the
Wasatchian-Bridgerian boundary within the vicinity of the
type areas of these North American Land-Mammal Ages. The
boundary is located considerably lower in the Wasatch
Formation than previously reported (i.e. Grande, 1984,

Sullivan, 1980).

LOCATION AND DESCRIPTION
The study area is located in the southwestern corner of
the Green River Basin, wyoming (Figure 1). It lies
equidistant between the towns of Opal and Carter, spanning
the Lincoln\Uinta county line (figure 2). The study area is
on the eastern limb of a large, gently dipping, north to
south-trending anticline. Many of the localities are

therefore on the western faces of small buttes and long

 

 

3
escarpments. The localities are typically separated by
broad, shallow, alluvium-filled valleys. In parts of the
study area, especially the northern portion, outcrops are
uncommon, the best ones being found along its eastern,

western and southern margins.

MATERIALS AND METHODS

The fossils of this study were collected during the
summers of 1989 through 1993 by joint University of
Michigan/Albion College/California State University at
Sacramento field parties. All fossils are accessioned at
the University of Michigan Museum of Paleontology (UM).
Most specimens were obtained by surface collecting.
Although a large quantity of excellent specimens have been
recovered over five seasons, most localities are actually
unfossiliferous compared to the classic higher Bridger beds.

Attempted screening for microvertebrates at several
localities did not produce a significant number of
vertebrate elements. A single locality, BB110, proved ideal
for screening and produced many microvertebrates, including
several taxa never before reported from the early Eocene of
the Green River Basin.

Fossils were identified by comparison with existing
collections, and from descriptions in the literature.
Detailed stratigraphic sections were measured in the study

area to determine the precise relationships of the fossil

 

 

4
localities. These sections are presented as Plate 2, and
along with aerial photos, were used in the construction of
the detailed geologic map presented as Plate 1, and to
reconstruct the depositional environments of the various

units.

PREVIOUS INVESTIGATIONS

The Bridger Basin of southwestern Wyoming has been the
focus of paleontological field investigation since the first
fossils were discovered in the early 18503 (West, 1976,
1990). Most of these studies have focused on either the
fishes of the predominantly lacustrine Green River Formation
or the mammals of the predominantly fluvial Bridger
Formation. Field investigations in the Bridger Formation
have concentrated on the highly fossiliferous middle Bridger
Beds in the southern part of the basin and have largely
ignored the comparatively fossil—poor lower and upper parts
of the Bridger Formation (Bridger A and E). West and
Hutchinson (1981) were the first to describe mammalian
fossils from the uppermost beds of the Bridger Formation
(Bridger E), confirming that these strata are Bridgerian in
age and that no rocks of Uintan age crop out in the southern
part of the Green River Basin.

Field workers from the University of Wyoming (Wood,
1966; Pledge, 1969; McGrew and Sullivan, 1970) were the

first to report vertebrate fossils from the Bridgerian A

 

Figure 1. Map showing the Green River Basin of
southwestern Wyoming and surrounding
mountains.

 

 

 

               

 

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Location Map of study area.

 

8
(late Brl) of the Green River Basin. Gazin (1952, 1962)
reported a number of excellent early Eocene vertebrate
localities along the northern, eastern, and western edges of
the Green River Basin. Although many of these localities
have produced only small collections, several (e.g., La
Barge and Knight Station) have provided large and diverse

collections.

LITHOSTRATIGRAPHY

A generalized stratigraphic section is presented as
Figure 3 to show the relationship of the various
lithostratigraphic units that outcrop within the study area.
A geologic map of the study area showing locations of
measured stratigraphic sections and fossil localities is
presented as Plate 1. Plate 2 is a correlation chart with
graphic representations of measured sections. The
stratigraphic relationship of the vertebrate fossil
localities is shown in figure 18. Written sections with
brief lithologic descriptions are provided in the appendix.
BRIDGER FORMATION

The Bridger Formation was named by F.V. Hayden in 1869
for a series of light green, brown, and gray fluviatile
sandstones and mudstones of middle Eocene age in the
southwestern Green River Basin. Since Hayden's original

description the formation has been found to extend to

 

 

 

ZO-fiDSQOWI an<-a znnao

Whiskey Butte Bed
\emnoan FORMATION

v

x

Craven Creek Bed
Laney Member

Upper Member

New Fork Tongue

Wilkins Peak
Member

Fonteneile Tongue

New Fork Tongue

Fonteneile Tongue

 

 

 

_‘\/7

La Barge Member

Undifferentiated Cretaceous

\W/VWAAANVWNNVWW

W i

20-dbiaOfl :04>m>£

 

 

Figure 3 .

Generalized stratigraphic column of the
Desertion Point-Little Muddy area.

10
include beds in northeastern Utah and northwestern Colorado
(Koenig, 1960). The formation reaches thicknesses exceeding
650 meters in the south-central part of the Bridger Basin
(Sullivan, 1980).

As noted above, Matthew (1909) separated the Bridger
Formation into five units, Bridger A through E using a
series of calcareous tuffs or "White Layers". Wood (1934),
utilizing Matthew's marker beds, divided the formation into
two members, the Blacks Fork Member (Bridger A and B), and
the Twin Buttes Member (Bridger C and D). Although these
terms are still in use by some authors as informal
biostratigraphic units (i.e. West, 1973; McGrew and
Sullivan, 1970), they have never received wide acceptance as
lithostratigraphic units. Koenig (1960), using solely
lithologic characteristics, suggested redividing the
formation into lower, middle, and upper Bridger Formation.
Koenig (1960) also subdivided the Lower Bridger into two
units. The lowermost of these, the lower Bridger A, crops
out within the study area.

WHISKEY BUTTE BED

Sullivan (1980), recognizing the need for revision of
the lithostratigraphy of the Bridger Formation proposed the
name Whiskey Butte Bed for a unit separated from the main
body of the Bridger Formation by the Craven Creek Bed of the
Laney Member of the Green River Formation. Within the field

area, the Whiskey Butte Bed consists of light gray

11

mudstones, siltstones and litharenites. The Whiskey Butte
Bed is a fluvial interval representing a regression of Lake
Gosiute. It separates two tongues of the lacustrine Laney
Member of the Green River Formation. The tongue of Bridger
Formation present at the eastern end of the study area
represents a more terrestrial interlude between two major
transgressions of ancient Lake Gosiute. The Whiskey Butte
Bed produces fossil vertebrates characteristic of the early
Bridgerian (Bridgerian "A", Br1.2).
WASATCH FORMATION

The Wasatch Formation was described by F.V. Hayden
(1873) for a sequence of brightly coloured fluviatile
sandstones, conglomerates, and mudstones in Echo and Weber
Canyons in northeastern Utah. Although the name Wasatch has
been used for the early Eocene sediments of many of the
intermontane basins of wyoming, Utah, and Colorado, it
should be restricted to the greater Green River Basin
(including the Washakie Basin and the type area in Utah;
West, 1973). The formation crops out extensively within the
study area, intertonguing with various units of the
comparatively drab Green River Formation.

LA BARGE MEMBER

The La Barge Member conformably underlies the
Fontanelle Tongue of the Green River Formation both in the
type area (Oriel, 1962) and within the study area. It is

comprised of brightly coloured mudstones, gray

 

12

sublitharenites, and thin, tan, micrite lenses. The La
Barge Member is approximately 150 meters thick in the type
area and up to 500 meters thick in the more central portions
of the basin. The La Barge Member rests unconformably on
the Lower Cretaceous Gannet Group. Extensive faulting
immediately west of the study area makes the precise
thickness of the unit difficult to ascertain. The La Barge
Member produces vertebrate fossils indicative of a
Lostcabinian subage (Wa7, latest early Eocene).

NEW FORK TONGUE

The New Fork Tongue was described by Donovan (1950) for
a series of variegated mudstones and poorly sorted
conglomerates and sandstones near the confluence of the
Green and New Fork Rivers. Bradley (1964) extended the
geographic range of the unit south to include most of the
upper layers of the Wasatch Formation along the western
margin of the Green River Formation. The term is used here
to designate several thick, cross-bedded, litharenites and
sublitharenites that intertongue with the Fontanelle Tongue
of the Green River Formation. Vertebrate fossils have not
been collected from the New Fork Tongue within the study
area.

UPPER MEMBER

This paper follows M'Gonigle and Dover (1992) in
referring to the upper strata of the Wasatch Formation as

the Upper Member. Within the study area the Upper Member

 

13

consists of series of bright red, white, purple and gray
mudstones with occasional, thick channel sandstones and
several minor sheet sandstones. Sullivan (1980) named these
layers the Desertion Point Member replacing the term "upper
tongue of the Wasatch Formation" used by Oriel (1962, p.
2162—2164) and other previous workers. The type locality,
as designated by Sullivan (1980, p.13) is "near Desertion
Point (sec. 26, T. 19 N., R. 115 W.) and eastward to Little
Muddy Creek in the Mulkay Spring Quadrangle. In this
locality the member is about 250 feet (76 meters) in
thickness". This is somewhat confusing since less than one
meter of the Wasatch Formation crops out at the base of
Desertion Point (see measured section 6, Plate 2). The
strata exposed at Desertion Point are the lignites, shales,
limestones and sandstones of the Laney Member of the Green
River Formation (approximately 25 meters thick). The
closest substantial outcrop of Wasatch Formation is
approximately 3 kilometres southwest of Desertion Point.

Within the study area the Upper Member of the Wasatch
Formation consists of two units. The upper unit is marked
by cycles of red, white, purple and gray mudstones and
siltstones with occasional litharenitic channel sandstones.
The lower unit consists of thick rust red mudstones and
siltstones, with thin limestone and sandstone interbeds.
The Upper Member produces vertebrate fossils indicative of

the earliest Bridgerian (Gardnerbuttean, Br1.l).

 

 

14

GREEN RIVER FORMATION

The Green River Formation was named by F.V. Hayden
(1869) for a thick sequence of lacustrine sediments of early
to middle Eocene age west of Rock Springs, Wyoming. The
formation consists of light gray, tan, and brown oil shales,
oolitic limestones, mudstones and litharenites. The
thickness of the formation varies from only a few meters
thick at the edges to up to 600 meters thick in the centre
of the Green River Basin. Within the study area and
throughout the Green River Basin, units of the Green River
Formation intertongue with both the Wasatch and Bridger
formations. The three units which crop out within the study
area are the Fontanelle Tongue, the Wilkins Peak Member, and
the Laney Member.

FONTANELLE TONGUE

The Fontanelle Tongue of the Green River Formation was
named by Donovan (1950, p. 63-64) to designate a series of
"alternating buff—brown sandstones and green and gray
mudstones that conformably overlie the Knight Member of the
Wasatch". The base of the Fontanelle Tongue is marked by a
thick, yellow, ostracod and gastropod-rich micrite that
fonms the cap of the prominent ridge that runs north-south
along the western side of the study area. A thick series of
poorly sorted, cross-bedded litharenites interpreted by
M'Gonigle and Dover (1992) as part of the Wasatch Formation

intertongues with the Fontanelle Tongue. The Fontanelle

 

 

15

Tongue conformably underlies the Wilkins Peak Member of the
Green River Formation.

WILKINS PEAK MEMBER

Bradley (1959) introduced the name Wilkins Peak Member
for strata in the Green River Basin that represent
intermittent lacustrine beds deposited during a period of
frequent vacillations in the level of Eocene Lake Gosiute.
This regression gave rise to a greater abundance of
evaporite minerals and carbonate rocks. Within the study
area the Wilkins Peak Member consists of gray-green
mudstones, thin, poorly sorted litharenites, and abundant,
thin, algal limestones. This unit is conformably overlain
by the Upper Member of the Wasatch Formation and conformably
overlies the Fontanelle Tongue of the Green River Formation.
A single specimen of Byzachygg collected near the base of
this unit is indicative of earliest Bridgerian deposition
(Gardnerbuttean, Br1.1).

LANEY MEMBER

The Laney Member was designated by Schultz (1920) for a
thick sequence of tan marlstones, brown oil shales, gray
mudstones and thin algal limestones in the Washakie Basin.
Bradley (1959) extended the unit to include beds formally
assigned to the Morrow Creek Member in the Green River
Basin. The Laney Member is the thickest unit of the Green
River Formation marking a major incursion of Eocene Lake

Gosiute throughout the area (Sullivan, 1980, Roehler, 1992).

 

 

16

Sullivan (1980) separated the basal portion of the Laney
Member into two distinct, laterally persistent tongues, the
lower, which outcrops within the study area, he named the
Craven Creek Bed. The upper unit which he named the Cow
Hollow Bed outcrops east of the study area. These tongues
are separated from each other by the more fluviatile strata
of the Whiskey Butte Bed of the Bridger Formation, but merge
basinward where Eocene Lake Gosiute attained greater depths
(Sullivan, 1980).

CRAVEN CREEK BED

The boundary between the Craven Creek Bed and the Upper
Member of the Wasatch Formation within the study area is
marked by a thin, although laterally persistent, lignitic,
tuffaceous mudstone. This bed contains abundant plant
debris in the form of broken leaves, stems and carbonized
wood. Above this the Craven Creek Bed consists of brown
oil-shales, gray to tan calcareous silty mudstones, gray
litharenites, occasional dark brown lignites and a few

interbedded algal limestones.

FOSSIL VERTEBRATE LOCALITIES
Fossil vertebrates have been recovered from 31
localities within the study area. These localities are
distributed throughout the Wasatch, Green River, and Bridger
formations. There are four localities in the Whiskey Butte

Bed of the Bridger Formation, twelve in the Craven Creek Bed

17
of the Laney Member of the Green River Formation, one in the
Wilkens Peak Member of the Green River Formation, nine in
the Upper Member of the Wasatch Formation, and five in the
La Barge Member of the Wasatch Formation. Fossil
vertebrates have not been collected from the Fontanelle
Tongue of the Green River Formation and the New Fork Tongue
of the Wasatch Formation within the study area. The
geographic distribution of the fossil localities is shown in
Figure 4. There is a general progression of older
localities on the west to younger on the east. A brief
description of each locality is provided below. The
topographic quadrangles are all from the United States

Geological Survey 7.5 minute series.

LOCALITIES
WASATCH FORMATION
UPPER MEMBER

B8013: Red, white, gray, and pink beds beneath the dark
brown lignitic layer, at the base of Desertion Ridge,
the low escarpment extending north from Desertion
Point. Wl/2, SW1/4, Section 23, and NW1/4 NW1/4
Section 26, T. 19 N., R. 115 W., Lincoln County, Mulkay
Springs Quadrangle.

BBOl4: Low red buttes and flats northeast of large, red

hill known as Big Dutch Butte. NE1/4, SW1/4, Section

18

 

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l
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I
I E33103 -
: “WWI
Wasatchian l (“.330 33037
I 33013 I ,3 I
f l (7 “3°“ o33033
Lostcabinian . mm ‘ mm
[nus : Gardnerbu1:tean \ ”3%:
I 33075 fl‘em
£331.16 I ”0'” v
A '1" “’37 i Ell/5T3 1 2
33114 r 3
mm. "m i 3'1'1 I i
run. I ””7
: @3117 33014- [1533013 ‘ '
| I m“ I Bridlgerian A
: 310:
l nos'v
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Figure 4. Map of study area showing localities and

biostratigraphic zonations.

19
4, T. 18 N., R. 115 W., Uinta County, Mulkay Springs
Quadrangle.

88051: Three prominent red and white variegated buttes,
400m north of Dry Muddy Creek and 3.3km west of Little
Round Mountain. SW1/4, SE1/4, Section 28 and NW1/4
NEl/4 Section 33 T. 20 N. R. 115 W., Lincoln County,
Little Round Mountain Quadrangle.

88068: Red, white, gray, and pink beds beneath the dark
brown lignitic layer, at base of Desertion Ridge.
SEl/4, NW1/4, Section 23, T. 19 N., R. 115 W., Lincoln
County, Mulkay Springs Quadrangle.

BBO75: White, gray, and tan beds beneath the dark brown
lignitic layer, at base of Desertion Point. SE1/4,
SW1/4, Section 26, T. 19 N., R. 115 W., Lincoln County,
Mulkay Springs Quadrangle.

88096: White flats and low buttes at the base of the
northeast end of the long, low, multi-coloured hill
known locally as Wasatch Butte, 2km north of Little
Muddy Creek. SEl/4, Section 4, T.18 N., R. 115 W.,
Uinta County, Mulkay Springs Quadrangle.

88097: SWl/4, NE1/4, Section 9, T. 18 N., R. 115 W., Uinta

County. Red, white, gray, and purple beds below prominent

white layer, bottom half of the southeastern end of Wasatch

Butte, 500m north of Little Muddy Creek, Uinta County,

Mulkay Springs Quadrangle.

20

88103: White, gray, and pink beds outcropping along a small
dry-wash, 2km west of northern end of Desertion Ridge.
NEl/4, NW1/4, Section 22, T. 19. N., R. 115 W., Lincoln
County, Mulkay Springs Quadrangle.

88104: Red, white, gray, and purple beds above the
prominent white layer, top half of Wasatch Butte, 900m
north of Little Muddy Creek. NW1/4, NEl/4, Section 9,

T. 18 N., R. 115 W., Uinta County, Mulkay Springs

Quadrangle.
LA BARGE MEMBER

88110: White, gray, purple, and red flats, 900m west of
Cumberland Ridge, 1.75km north of Little Muddy Creek.
NEl/4, SW1/4, Section 34, T. 19 N., R. 116 W., Lincoln
County, Cumberland Gap Quadrangle.

88114: White and purple mudstones, and gray litharenite at
small exposure, 100m south of the long escarpment near
the western margin of the study area known locally as
Cumberland Ridge, 1.75km north of Little Muddy Creek.
Centre of eastern boundary of Section 34, T. 19 N., R.
116 W., Lincoln County, Cumberland Gap Quadrangle.

88115: White, red, and orange mudstones at the base of the
north face of Cumberland Ridge. SW1/4, SWl/4, Section

26, T.19 N., R. 116 W., Lincoln County, Mulkay Springs

Quadrangle.

21

88116: Lowest units along prominent variegated ridge.
Includes all units beneath the orange mudstone at the
south western corner of the western extension of
Cumberland Ridge. SW1/4, NEl/4, Section 34, T. 19 N.,
R. 116 W., Lincoln County, Cumberland Gap Quadrangle.

88118: Orange and yellow mudstones along the lower part of
the western extension of Cumberland Ridge. SW1/4,
NEl/4, Section 34, T .19 N., R. 116 W., Lincoln County,
Cumberland Gap Quadrangle.

BRIDGER FORMATION

WHISKEY BUTTE BED

88035: Gray and white mudstones and litharenites of Top Hat
Butte, a small hat-shaped hill on Desertion Ridge.
NWl/4, SEl/4, Section 23, T. 19 N., R. 115 W., Lincoln
County, Hampton Quadrangle.

88037: Gray and white beds on northeastern side of the

long, low butte east of Top Hat Butte, top of Desertion

Ridge. NEl/4, SE1/4, Section 23, T. 19 N., R. 115 W.,

Lincoln County, Hampton Quadrangle.

88038: Gray and white beds on southeastern side of the
long, low butte east of Top Hat Butte, top of Desertion
Ridge. NEl/4, SEl/4, Section 23, T. 19 N., R. 115 W.,

Lincoln County, Hampton Quadrangle.

22

88044: Gray and white beds on southwestern side of the
long, low butte east of Top Hat Butte, top of Desertion
Ridge. NW1/4, SEl/4, Section 23, T. 19 N., R. 115 W.,
Lincoln County, Hampton Quadrangle.

GREEN RIVER FORMATION

LANEY MEMBER, CRAVEN CREEK BED

88012: White, gray, and tan beds above the dark brown
lignitic ash layer, top half of Desertion Point. SEl/4,
SW1/4, Section 26, T. 19 N., R. 115 W., Lincoln County,
Mulkay Springs Quadrangle.

88013w: Low gray, green, and white butte 300m west of base
of Desertion Ridge. SEl/4, SEl/4, Section 22, and
NEl/4, NEl/4, Section 27, T. 19 N., R. 115 W., Lincoln
County, Mulkay Springs Quadrangle.

88019: Gray and white beds south of the broad dry wash at
the south end of Desertion Ridge. NEl/4, NW1/4,
Section 2, T. 18 N., R. 115 W., Uinta County, Hampton
and Mulkay Springs Quadrangles.

88036: Tan, green, and gray beds above the dark brown
lignitic layer, top half of Desertion Ridge. W1/2,
SW1/4, Section 23, and NW1/4, NW1/4, Section 26, T. 19
N., R. 115 W., Lincoln County, Mulkay Springs

Quadrangle.

23

88069: White, gray, and tan beds above the dark brown
lignitic layer, top half of Desertion Ridge. SEl/4,
NW1/4, Section 23, T. 19 N., R. 115 W., Lincoln County,
Mulkay Springs Quadrangle.

88070: White, gray, and tan beds along Desertion Ridge.
SEl/4, SW1/4, Section 26, T. 19 N., R. 115 W., Lincoln
County, Mulkay Springs Quadrangle.

88072: White, gray, and tan beds 900m south of Little Muddy
Creek. NEl/4, NW1/4, Section 14, T. 18 N., R. 115 W.,
Uinta County, Hampton and Mulkay Springs Quadrangles.

88074: Brown, tan, gray, and white beds at southeastern end
of Desertion Ridge. SEl/4, SEl/14, Section 26, and
NEl/4, NEl/4, Section 35, T. 19 N., R. 115 W., Lincoln
County, Hampton Quadrangle.

88076: White, gray, and tan beds along Desertion Ridge.
SEl/4, NWl/4, Section 26, T. 19 N., R. 115 W., Lincoln
County, Mulkay Springs Quadrangle.

88077: Tan, gray, and white beds along northern face of
butte south of the broad wash at the southern end of
Desertion Ridge. SW1/4, SEl/4, Section 35, T. 19 N.,
R. 115 W., Lincoln County, and NE1/4, NW1/4, Section 2,
T. 18 N., R. 115 W., Uinta County, Hampton and Mulkay

Springs Quadrangles.

24

88098: Brown, tan, gray, and white beds at southwestern end
of Desertion Ridge. SW1/4, NEl/4, Section 35, T. 19
N., R. 115 W., Lincoln County, Mulkay Springs
Quadrangle.

88109: Tan, gray, and white beds along cliff 3.6km south of
Little Muddy Creek. SW1/4, NW1/4, Section 23, T. 18
N., R. 115 W., Uinta County, Mulkay Springs Quadrangle.

WILKENS PEAK MEMBER

88117: Gray mudstone immediately above the poorly sorted
litharenite on the western side of prominent point.
SEl/4, NEl/4, Section 1, T. 19 N., R. 116. W., Uinta

County, Mulkay Springs Quadrangle.

25

FAUNAL LIST

Kingdom Monera
Division Cyanophyta
stromatolitic cyanophytes

Kingdom Animalia
Phylum Arthropoda
Class Crustacea
Subclass Ostracoda

Phylum Mollusca
Class Gastropoda
Order Mesogastropoda
Family Viviparidae
Vivingrug trochiformig
Family Pleuroceridae
Wm
Order Basommatophora
Family Physidae
Physa bridgerensis
Family Planorbidae

Biggphlaria sp.
Order Stylomatophora
Family Uropcoptidae
met 8. mi
Family Bulimulidae

Orggcgnug cf. 9. nlggisnirg

Class Pelecypoda
Ord., Fam., gen. et sp. indet.

Phylum Chordata
Class Osteichthyes
Order Lepisosteiformes
Family Lepisosteidae
Lgnisosteus cunegtus
Lepisogggug sp. indet.
Order Amiiformes
Family Amiidae
Amie sp. indet.
Order Siluriformes
Family Ictaluridae
genus and species indet.

Class Reptilia
Order Testudines
Family Baenidae

gaggg ergngsa

 

26

Family Emydidae
Echmategys yxomingensis
g. septaria
Eghmategys cf. g. cibollensis
Echmategys sp. indet.
Family Trionychidae
cf. Platxneltis sp. indet.
Family Dermatemydidae
Bantemys fluviatalig

Bantemys sp. indet.
Family Carettochelyidae

Anogteira radulina
Order Squamata
Family Iguanidae
Parasaurgmalus olseni
Family Anguidae
WW
Xestops cf. 3. vagans
Xestops sp. indet.
Family Boidae
Calamagras primug
Indeterminate amphisbaenid
Order Crocodilia
Family Alligatoridae

Alloggathosgghng sp. indet.
Dinlocxnodon sp. indet.
Family Crocodylidae
Mamie
new genus (?) and species
Family Pristichampsidae
Priggicgggpgug vorex
Class Mammalia

Infraclass Metatheria
Order Marsupialia
Family Didelphidae
Pergghgrium inngmiggggg

g. ggggtgcki
Infraclass Eutheria

Order Insectivora
Family Apatemyidae
cf. Apggggyg sp. indet.
Family Pantolestidae
Palaeosinong cf. g. 1353;911
Family Lepticidae
galaeictopg bigugnig
Family Dormaalidae
WM
5. nrigcgg

27

Order Proprimates
Family Paromomyidae
Iggacius graxbullianns
Family Microsyopidae
Microsyops elegggg
Microsxons cf. M. scogtianus
Microsxons sp. indet.
Order Primates
Family Adapidae -
Cantius cf. Q. frugivorous
Notharctug ggbiggggi
Conelemur cf g. ausgraloguggg
gmilodecteg mcgrewi
Smilodectes sp. indet.
Family Omomyidae
Queers 9111211
Omomys cf. 9. cgrtgri
washakius insignia
Anemorhxsis near 5. wortmani
Order Creodontidae
Family Hyaenodontidae
genus and species indet.
Order Carnivora
Family Miacidae
811218 12111222

vulnavus profectus
Family Viverravidae

‘viverrevus gracilis
Viverravug sp. indet.
Order Condylartha
Family Meniscotheriidae
Mgniscotherium chéggnse
Meniscotherigg sp. indet.
Family Hyopsodontidae
Hyopsodus cf. g. minisgulug
Hyopsodus cf. g. migiculus
Hyopsodug cf. g. wortgégi
Order Taeniodonta
Family Stylinodontidae
genus et sp. indet.
Order Tillodontia
Family Esthonychidae
Egthonyg ggutidens
Order Artiodactyla
Family Dichobunidae
2112292115 gasses
211221211; sp. indet.

28

Order Perrisodactyla
Family Equidae
MM
Orohippus sp. indet
eracotherium vasacciense
Family Brontotheriidae
Lambdotherium.popoagacium
Paleosyops cf. 2. fontinalis
Family Helaletidae
Hyrachygs modestus
22122212222 sp. indet.
Order Rodentia
Family Sciuravidae
gciuravus nitidus
Knightogys depregsus
Family Paramyidae
Parggys cf. g. excavatus
Leptotomns narvug

Lentotomus sp. indet.
Order Incertae sedis

Family Metacheiromyidae
Metacheirogxs sp. indet.
Pelaeanodon sp. indet.

Family Epoicotheriidae
Tgtrenagsalus sp. indet.

3“

29

SYSTEMATIC PALEONTOLOGY

The following is a discussion of the fossils found
within the thesis study area. While all fossils recovered
are described, special attention is given to the
vertebrates, and in particular to the mammals. In all cases
the locality is given along with the specimen description.

A box labled "miscellaneous" has been retained for each
locality containing invertebrates and isolated vertebrate
bones and bone fragments not identifiable to the family
level. The intention is to document the changes in the
composition of the vertebrate community within the study
area during the early middle Eocene. Measurements made with
dial callipers calibrated to 0.1mm are presented where
appropriate.

Basic invertebrate classification follows the Treatise
on Inyertebrate Paleontology (Moore, 1961). Gastropod
classification follows that of Henderson (1935), Taylor and
Sohl, (1962), and Hanley (1974). Non-mammalian vertebrates
were classified according to Carroll (1988) and King and
Burke (1989). Mammalian classification on the ordinal and
familial levels follows Simpson (1945) and McKenna (1975).
Mammalian classification, particularly that of extinct taxa,
has undergone considerable revision in the last several

decades however, so a variety of sources were used for more

3O
jprecise classification of the mammals from the study area.
These are referenced in the discussion of each individual
taxon. The known chronological ranges of the mammals
discussed below were obtained from Woodburne (1987), and if
necessary, were updated from newer sources referenced in the
discussion. North American Eocene biostratigraphy is

discussed briefly in the section following systematic

paleontology.

(I)

T

(I:

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31
Kingdom Monera Linnaeus, 1758

Remarks: Kingdom Monera contains the earliest and
simplest forms of life on earth. All members of this group,
the bacteria and the cyanobacteria, are single—celled,
prokaryotic organisms.

Phylum Cyanophyta Steinke, 1931
Class indet.

Remarks: Colonial algal structures known as
stromatolites are ubiquitous in the limestone layers of the
Laney and Wilkens Peak members of the Green River Formation.
Although many authors use the term stromatolite to indicate
strictly marine organisms, others use it in reference to any
colonial algal structure (Awramik, 1990). The term as used
here follows the usage of Surdam and Wray (1976) and
indicates an organosedimentary structure formed by sediment
trapping within microbial communities in either a marine or
lacustrine setting.

Fresh water stromatolites have long been known from the
Green River Formation (Bradley, 1928; Surdam and Wray,
1976). Wood (1966) and Pledge (1969) reported large
ellipsoidal algal pods, likely fresh water stromatolites
from the low Bridger (Bridger A) beds northeast of the study
area. Pledge (1969) reports that these algal pods developed
on inundated stumps and fallen trees in the shallow water at
the edge of Eocene Lake Gosiute. Grande (1984) reported

algal pods (oncolites) that developed on the fossil

~a.

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32
gastropod Gonigbasis tenera. Stromatolites have not been
reported from the Wasatch Formation which consists primarily
of terrigenous fluvial deposits.

As indicated above Stromatolites are particularly well
developed in the Laney Member along the Desertion Point
escarpment, especially in two thin micritic limestones.
Abundant intermittent stromatolite layers differentiates the
Wilkens Peak Member from the underlying Fontanelle Tongue.
In most cases the algal pods in the Laney Member form in
concentric ellipsoidal structures that range in size from a
few centimetres to a meter or more. Consistent with the
observations of Pledge (1969), and Grande (1984) several of
the smaller algal pods formed around gastropods,
particularly gggigbggig, and many of the larger pods formed
as encrustations around submerged logs. Unlike most of the
stromatolites in the Laney Member, algal structures in the
Wilkens Peak Member tend to be more stratiform constructions
than concentric ellipsoids.

Stromatolites and other related algal structures are
useful indicators of environment. Stromatolites indicate
the presence of photosynthesizing microbes which require
abundant light, suggesting shallow water and the proximity
of the shore (Bradley, 1928). Awramik (1990) argues that
not only do stromatolites form in shallow water, they can

actually form under intermittent conditions of submersion.

33
Stromatolites are also indicative of quiet, perhaps stagnant

water and the absence of aquatic grazers (Awramik, 1990).

Kingdom Animalia Linneaus, 1758
Phylum Arthropoda Siebold and Stannius, 1845
Subphylum Mandibulata Clairville, 1798
Class Crustacea Pennant, 1777
Subclass Ostracoda, Latrielle, 1806
Family indet.

Remarks: Ostracods are common in limestone lenses in
the Laney Member and Fontanelle Tongue of the Green River
Formation, particularly in a thick gastropodal limestone on
the western side of the study area. Swain (1964), Baer
(1969), and Oriel and Tracey (1970) reported a large variety
of ostracods from the lacustrine beds of the Green River
Formation in both the Bridger and Fossil basins. The
ostracods from the study area have not been studied in

detail.

Phylum Mollusca Linneaus, 1758
Snails and bivalve fragments are common within the
study area. These taxa have not been studied in detail,
however several taxa have been identified. Grande (1984)
gives a brief synopsis of the Green River molluscan fauna.

Although the overall diversity reported by Grande (1984) is

 

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34
lrbgher, the molluscs from the study area do not differ
(greatly from those reported by Grande.
Class Gastropoda Cuvier, 1797
Order Mesogastropoda Theile, 1925
Family Viviparidae Montfort, 1810
Genus Viviparus Montfort, 1810

Aga,aag Distribution: Cretaceous to recent of North
.America, Africa, Europe, and Asia.

Remarks: Extant members of the genus Viviparus have
been found in a wide variety of environmental conditions.
They are found in both lakes and rivers and in depths
ranging from a few centimetres to nearly three meters. La
Rocque (1960) felt that the presence of Viviparug is
indicative only of an abundant food supply in the form of
lower plants and decaying animal matter rather than a
particular ecological niche. Viviparus requires clean,
oxygenated water (Richardson, 1928), and is able to
aestivate during drought (Hanley, 1974).

Vivipagga Ergghifgrmis Meek and Hayden, 1856

Matarial: UM 98713m- complete shell, collected at
88073, June 28, 1991. UM 101101m- damaged shell, collected
at 88110, August 5, 1993.

Ramarka: UM 98713m is a large individual of 211122£2§
grgghifgrmis measuring 39mm in length and 35mm in width, UM
101101m is approximately half the size. Both shells are

dextral and rather thin with abundant fine, closely spaced

35
growth lines. UM 98713m is somewhat ovaline in cross-
section due to post-depositional deformation.
Family Pleuroceridae
Genus Goniobasis Lea, 1862

Aga aag Distribution: Cretaceous to recent of North
America, Africa, Europe, and Asia.

Remarks: Gastropods of the genus Goniobasis are one of
the most common molluscan fossils found in the Eocene of
western wyoming. Extant species of goniobasia are common
throughout North America in a broad range of aquatic
ecological niches. They are typically only found in
permanent water situations (Hanley, 1974). Notably, some
extant species show remarkable tolerance to fluctuations in
environmental conditions such as salinity and turbidity
(Goodrich, 1944). This is an important consideration in
Eocene Lake Gosiute which fluctuated from fresh to very
saline water at various times in its history (Surdam and
Wolfbauer, 1975).

aniggagia tanara Hall, 1845

Magarial: UM 95670m- shells of two individuals,
collected at 88051, June 15, 1990. UM 98577m- four shells,
collected at 88037, June 20, 1991. UM 98579m— three shells,
collected at 88044, June 20, 1991. UM 100896m— two shells,
collected at 88114, July 25, 1993. UM 101101m- 14 shells,

collected at 88110, August 5, 1993.

36

Remarks: Goniobasis tenera is the most common
gastropod collected within the study area, particularly
within the Green River Formation Several layers in the thick
basal limestone of the Fontanelle Tongue at the western edge
of the field area are comprised predominantly of Q. tenera.
Q. tagera specimens recovered from the study area display
considerable morphological variation.

La Rocque (1960), studying Q. tenera from the Flagstaff
Formation (Late Palaeocene to Early Eocene) of central Utah,
established that there were four main morphotypes (labled
forms A-D) of Q. ganera that were for the most part,
separated from each other stratigraphically. Although
specimen UM 95670m.from the upper Wasatch Formation most
closely resembles Form C of La Rocque (1960) there are some
significant differences. The specimen has the well
developed plications and prominent nodes on the centre of
each whorl that Form C has but also possesses carinae over
the entire body of each whorl similar to Form 8, rather than
only on the base as in Form C. The specimens from the La
Barge Member of the Wasatch Formation and the Fontanelle
Tongue of the Green River Formation are smooth, without any
type of plications or nodes, and with only subtle carinae.
This is most similar to Form D of La Rocque (1960). The
specimens from the Bridger Formation (UM 98577m, UM 98579m),
do not have nodes, possess strong plications, and have

carinae that cover the entire whorl, similar to Form B.

37
Similar to the specimens studied by La Rocque (1960)
the three morphotypes come from stratigraphically distinct
horizons and may indicate separate invasions of the species
into the study area. Alternatively, the variance in
morphotypes between the three formations may reflect the
different habitats in which the units were deposited

(Bartels, pers. comm.).

Order Pulmonata
Family Physidae Draparnaud, 1801
Genus £2122 Draparnaud, 1801
Aga aag Distribution: Pennsylvanian to Recent of North
America, Europe, Asia, and Africa.
Ramarka: Modern members of the genus ggzaa are

considered among the "hardiest" of the freshwater molluscs

(La Rocque, 1960). They are generally found in very shallow
water. Phgaa in association with other pulmonate gastropods

such as Bionhlaria may be indicative of the poorly drained
marshy wetlands adjacent to Lake Gosiute (Hanley, 1977).
Surdam and Wolfbauer (1975) note that the presence of ggxaa,
a lung breathing gastropod indicates very shallow water and
emergent vegetation. A single species of ggyaa has been
found within the study area.
£2222 briagerensig Meek 1872
Magerial: UM 98577m- single shell, collected at 88037,

June 20, 1991. UM 98713m- complete shell, collected at

38
88073, June 28, 1991. UM 101103m— single shell, collected
at 88118, August 5, 1993.

Remarks: Consistent with specimens figured in Grande
(1984), ggzaa bridgerensis from the study area are small,
sinistral, pulmonate gastropods. They are smooth shelled
with very fine, closely spaced growth lines. They are
slightly oval in outline and have regularly increasing
whorls.

Family Planoribidae Hubendick, 1955
Genus Biogphlaria White, 1876

Aga aag Distribution: Cretaceous to recent of Europe,

North America, Asia, and Africa.
Biogphlaria sp. indet.

Matarial: UM 95602m- two shells, collected at 88036,
June 5, 1990. UM 98577m- single shell, collected at 88037,
June 20, 1991. UM98688- single shell, collected at 88070,
June 28, 1991. UM 98713m- six shells, collected at 88073,
June 28, 1991. UM 101026m- two shells, collected at 88038,
August 1, 1993.

Remarks: Biogphlaria is a small, low-spired, thin-
shelled pulmonate gastropod. As mentioned above Biggphlaria
in association with 22122 is considered indicative of the
lowlands contiguous to Lake Gosiute (Hanley, 1974).

Order Stylommatophora
Ramarka: Two genera of stylommatophoran gastropods,

Bolggpira and Oragggnus, have been recovered from the

39
lowermost beds of the Wasatch Formation within the study
area. Hanley (1976) attributed these molluscs to the hot,
humid, forested, calcium-rich lowlands adjacent to Lake
Gosiute.
Family Urocoptidae Pilsbry, 1902
Genus Bolggpira Martens, 1860

Aga aag Distribution: Palaeocene to Recent of western
North America.

Bgloapira cf. Q. granaeri Cockerell, 1914

Material: UM 101101m— Single shell, collected at 88110,
August 5, 1993.

Remarks: Cockerell (1914) described the species from
an incomplete shell approximately 10mm in length from the
Palaeocene Torrejon Formation of New Mexico but did not
designate a catalogue number for the type. Similar to the
type, the solitary specimen referred to Bgloapira cf. Q.
agaagaga is damaged and does not retain the aperture. UM
101101m.is identical to the photographs in Mckenna et a1
(1962) and Cockerell (1914). It consists of ten whorls
increasing in width. The specimen is approximately the size
and shape of a blowfly larva and was initially mistaken for
one. The whorls are a single continuous ribbon, not the
individual lamellae characteristic of fly larvae. Abundant

minute growth lines are apparent under high magnification.

4O
Extant Bolospira are found in hot, arid, calcium rich
environments (Pilsbry, 1946). Gingerich (1989) considered
Boloanira indicative of high, well-drained floodplains.
Family Bulimulidae Zilch, 1959
Subfamily Oreohelcinae Pilsbry, 1946
Genus Oreoconus Taylor, 1962
Aga aag Distribution: Lower Eocene through lower

Oligocene of western and central Wyoming.

Type Specias: Oreocgnaa planispira Taylor, 1962

Oregconua cf. Q. planianire

Hglgtype: USNM 647848- single shell, collected from
the Bridger Formation at Tabernacle Butte, Wyoming (Br2).

Magarial: UM 101101m- Single shell, collected at
88110, August 5, 1993.

Remarks: Oreoconus planignira is a medium sized,
conical shelled, terrestrial gastrOpod. The species is
poorly known. It is considered diagnostic of a terrestrial
habitat since most specimens have been collected in
association with other terrestrial gastropods (McKenna a;
a;., 1962; Hanley, 1974).

Class Pelycepoda Goldfuss, 1820
Ord., Fam., Gen. et sp. indet.

Magarial: UM 98733m- single valve, collected at 88012,
June 29, 1991.

Ramarka: Fragments of pelecypod valves are common at

most localities along Desertion Point Ridge. A single

41
complete valve of an indeterminate pelecypod was collected
within the study area. This specimen does not match the
description of any pelecypod described by Grande (1984), La

Rocque (1960) or Hanley (1976, 1977).

Phylum Chordata Haeckal, 1874
Subphylum Vertebrata Linnaeus, 1758
Class Osteichthyes Muller, 1846
Fish remains in the form of isolated skeletal elements

are ubiquitous in the upper beds of the study area,
particularly in the Laney Member of the Green River
Formation. The lower, more terrigenous beds rarely contain
fish material. Most of these fish remains are indeterminate

fragments of teleosts and the scales and vertebrae of

Leniaoggeus and.Amia.

Superorder Holostei Muller, 1846
Order LEPISOSTEIFORMES Hay, 1929
Family Lepisosteidae Cuvier, 1825
Genus Lepisosteus Lacepede, 1803
Aga agg Disgripugion: Lepisostega is known from the
Late Cretaceous to Present. During the Cretaceous they were
world—wide in distribution but today they are limited to
North and Central America and Cuba. Using track analysis of
the biogeographic distribution of the gar, Wiley (1976) gave

a minimum age for the genus as middle Jurassic.

42

Type Species: Lepisosteus gavialis Jordan and Evermann,

1896.
Lepispsteus cuneatus (Cope, 1878)
Holotypa: AMNH P.2517- Complete fish with crushed

skull, from an unknown locality in the Manti Beds of the
Green River Formation, Utah.

Material: UM 95602m- two parietals, collected at
88036, June 5, 1990. UM 98775m- four parietals and two
dermopterotics, collected at 88069, June 30, 1991. UM
99659m- crushed skull including cleithra, basioccipital,
part of the pterygoid, and a fragment of the opercular,
collected at 88070, June 23, 1993.

Remarka: 22212222222 cunaapas is present in most of
the lacustrine and fluviatile deposits in the Eocene of
North America. The various bones of the skull are covered
by elongate enameloid tubercles. It differs from all
extinct and extant species of Lapisogtepa with the exception
of L. ppapppfi in having wide interconnecting enameloid
ridges rather than thin discontinuous ridges on the
parietals and dermopterotics (Wiley, 1976). L. cun a
differs from.;. ppapppa in having a reduced number of
thicker interconnecting ridges (Wiley, 1976).

Lapigpppapa sp. indet.

Maparial: Abundant vertebrae and scales have been

recovered from the following localities: 88012, 88013,

88019, 88035, 88036, 88037, 88038, 88044, 88068, 88069,

43
88070, 88072, 88074, 88075, 88076, 88077, 88098, and 88109.
A few isolated scales have been recovered from 88110, 88114,
and 88118.

Remarks: Lepisosteus, the gar, is known from three
species in the Green River Formation (Grande, 1984).
Lepispstaua cuneatus (see above) is the only species known
from Green River deposits outside of Fossil Basin and has
been recovered from the study area (see below). Modern gars
prefer swamps, bayous, shallow sluggish pools, backwaters of
rivers and streams, and occasionally brackish lagoons (Page
and Burr, 1991). They are primitive fish, and along with
the bowfin (see below) are the only non-tropical air-
breathing fish (Moyle and Cech, 1982). Lapiapgpaaa is known
from isolated vertebrae and scales from most localities on
the eastern side of the study area, and from jaw fragments
from several of these localities. Lepispsteps vertebrae are
unique among fish in being procoelous rather than
amphicoelous. This is thought to be related to the weight
of the scaled armour the fish possess (Moyle and Cech,
1982). This armour protected gars from predation by
everything except crocodilians (Grande, 1984). The thick
ganoid scales that comprise this armour are easily
identified by their elongate trapezoidal shape. The teeth

are acrodont and needle-like.

44
Order Amioidea Huxley, 1861
Family Amiidae Cuvier, 1825
Genus Apia Linnaeus, 1766
Aga apg Distribution: Late Cretaceous to Present of
North America and Europe.

Type Species: Ania calva Linneaus, 1766.

 

Apia sp. indet.

Material: Abundant vertebrae and scales have been
recovered from the following localities: 88012, 88013,
88019, 88035, 88036, 88037, 88038, 88044, 88068, 88069,
88070, 88072, 88074, 88075, 88076, BB077, 88098, and 88109.

Remarks: Apia, the bowfin, is represented in the Green

River Formation by two species, Amie ainpaansia and A.

 

fragpaa. Both species are common throughout the formation.
Along with the gar, bowfins are the only non-tropical air-
breathing fish (Moyle and Cech, 1982). Modern bowfins are
found in swamps, sloughs and shallow pools, usually near
vegetation. The cycloid scales that comprise the armour of
this primitive fish are easily identified by their rounded-
off rectangular shape. The scales are usually slightly

concave and are much thinner than those of the gar.

Superorder Teleostei Owen, 1847
Order indet.
Maparial: Abundant vertebrae, spines, ribs, and skull

fragments have been recovered from the following localities:

45
88012, 88013, 88019, 88035, 88036, 88037, 88038, 88044,
88068, 88069, 88070, 88072, 88074, 88075, 88076, 88077,
88098, and 88109.

Remarks: Although abundant teleost fossils have been
recovered from the study area, they are, with the exception
of the catfish spines described below, extremely fragmentary
in nature. Most studies of the Green River fish fauna have
been conducted in the richer strata of the Fossil and Uinta
Basins. Grande (1984) reviewed the fish fauna of the Green
River Formation. No new information on the teleosts of the

Green River Formation can be added here.

Order SILURIFORMES
Family Ictaluridae
Genus and species indet.

Aga app Distripution: Palaeocene to Recent, North
America.

Maperial: UM 95600m- Base of dorsal spine, collected
at 88013, June 29,1990. UM 98735m- Base of dorsal spine,
collected at 88077, June 29, 1991.

Remarka: Two genera and three species of ictalurid
catfish have been reported from the Green River Formation
(Grande, 1984). The only easily identified elements are the
long serrated dorsal and pectoral spines. Ictalurids are

probably more common than the identified fossils might

 

46
suggest since most other isolated skeletal elements of

catfish look similar to those of other teleostean fish.

Class Reptilia Laurenti, 1768
Subclass Anapsida Osborn, 1918
Order TESTUDINES Batsch, 1788
Suborder Cryptodira Cope, 1869
Ramarks: The remains of turtles are the most abundant
tetrapod fossils within the study area. The majority of the
specimens are fragmented carapaces and plastrons and are of
limited use. Several excellent specimens have been
recovered, however, largely consisting of complete
carapaces and plastra. Few of these have any associated
skeletal material and only a single fragmentary skull has
been found.
Superfamily Baenoidea Williams, 1950
Family Baenidae Cope, 1869
Subfamily Baeninae Williams, 1950
Genus Qaapa Leidy, 1870
Aga app Distribution: Early to late Eocene (Wasatchian
to Uintan) of Wyoming and Utah.

Typa Qpeciea: Baena aranpaa Leidy, 1870

22222 2292222 Leidy, 1870
leopypa: USNM 103- partial carapace, collected near

the junction of the Big Sandy and Green Rivers, lowermost

Bridger Formation (Brl).

47

Material: UM 98663-fragmentary skull, complete
mandibles, fore and hind limb elements, carapace and
plastron fragments, collected at 88013, June 28, 1991. UM
98690- Complete plastron and partial carapace of large
adult, collected at 88069, June 28, 1991. UM 98714—
carapace and plastron fragments with associated limb
elements, collected at 88036, June 28, 1991. UM 98718-
carapace and plastron fragments, collected at 88013, June
29, 1991.

Ramarks: UM 98690 is a specimen of a relatively old
turtle. All traces of the sutures between the various bones
of the plastron are obliterated through co—ossification. No
traces of the pattern of the epidermal covering remain. The
other three specimens were much younger and smaller
individuals and retain obscure suture lines.

The plastron of Qaapa aranpse is comparatively blunt at
both ends. The posterior margins of the xiphiplastra are
rounded and only slightly concave. The vertebral scutes are
wide and rectangular. The carapace fragments are moderately
thick. The skull is short and wide. The mandibles are
robust, and possess a deep groove on the medial surface.

The condylus mandibularis is rectangular and concave unlike
the tear drop shaped bone in the closely related Chiaparnpn
(Gaffney, 1972).

48
Superfamily Testudinoidea Baur, 1893
Family Emydidae Lydekker, 1889
Genus Echmatepys Hay, 1906
Aga apg Distribution: Eocene (WaO—Ui2) of North
America.

H22 21022122: 2M2 222221212 Cope, 1873

Echmatepys septaria Cope, 1873

Holotype: The type is in the United States National
Museum, and consists of carapace fragments and a complete
plastron, collected in the Washakie Basin near South Bitter
Creek, Wyoming.

Matarial: UM 95598— Nearly complete plastron, most of
the carapace, some postcrania including a large claw,
collected at 88013 on June 4, 1990. UM 98717— complete
plastron and nearly complete carapace, collected at 88076,
June 29, 1991. UM 98693— Complete plastron, carapace
fragments, collected at 88013w, June 28, 1991. UM 98722-
partial plastron including right epiplastron, collected at
88074, June 29, 1991. UM 101024- right epiplastron,
collected at 88037, August 1, 1993. UM 101028- right
epiplastron, collected at 88036, August 1, 1993.

Ramarka: Eghmapepya aepparie is the most common emydid
turtle found within the field area. It differs from Q.
pyppipgapaia (see below) in having a narrow epiplastron with
distinct tubercles set near the medial suture, a thick

margin, and a deep epiplastral trough (figure 5) and

’1

49
massive, medial bridge extensions on the hypoplastron. This
turtle is indicative of lacustrine or near—lake fluvial
environments (Bartels, 1993).
Echmatapys pyomingensis Leidy, 1869

Holotype: The type is in the collection of the Academy
of Natural Science, Philadeplhia, and consists of an
isolated left epiplastron, collected in the Bridger Basin,
near Fort Bridger, Wyoming.

Material: UM 95602m- right xiphiplastron, collected at
88036, June 4, 1990. UM 98717— Complete carapace and
plastron, collected at 88076, June 29, 1991.

Remarks: Echmatapys pyominganais differs from.§.
aaptaria above in having a wider epiplastron with indistinct
tubercles more distant from the medial suture, a thin
margin, and a comparatively wide, short, and shallow
epiplastral trough (figure 5). Q. pyominganaia is
considerably less common than E- saptaria within the field
area. The turtle is restricted to fluvial environments
(Bartels, 1993).

Apppapapya cf. a. pipollanais (Cope, 1902)

Holotype: USNM 2576- fragments of the plastron,
collected from the Wasatch beds of New Mexico in the
vicinity of the Gallinas River.

Mapariai: UM 101153- carapace and plastron fragments
including the epiplastron, collected by at 88097, August 5,

1993.

 

50

Remarks: This interesting species of Echmatepys is
known from a single specimen within the study area. It is
significantly different from the other two species of
Qappapapya found within the study area. The tubercles on
the epiplastra (Figure 5) are large, distinct and pointed,
and set near the medial suture. The tubercle is much more
pointed and elongate than in either A. saptaria or Q.
pypminganaia. The ventral surface is indented beneath the
tubercles unlike either of these species. The margin,
although thin like in Q. septaria, extends the entire length
of the short medial suture. Like many modern terrestrial
forms, the carapace and plastron are thick.

Echmatapys sp. indet.

Maperial: UM 98668m- carapace and plastron fragments,
collected at 88013, June 25, 1991. UM 98704m— carapace and
plastron fragments, collected at 88072, June 28, 1991. UM
98714- Fragments of the carapace and plastron, some limb
elements, collected at 88036, June 28, 1991. UM 98715-
complete entoplastron, fragments of hyoplastron, and
epiplastron, collected at 88070, June 29, 1991. UM 99635m—
carapace and plastron fragments, collected at 88037, June
17, 1992.

Ramarka: These specimens unfortunately do not retain

any of the diagnostic characters which differentiate between

Apppapapya pygmingangia and Q. aappapia. The thinner shell

51

Figure 5. Epiplastra of Echmatepys species from the
study area. A. Q. pyomingenais (UM 98717),
8. Q. sepparia (UM 101024) C. Q.
pibpllanaia (UM 101153). Bars are one
millimeter in length.

 

 

A.
Emmm
IN 98711:
me
E .
C .

Figure 5

53
eazil<ii less stream—lined plastral fragments make it unlikely
t:1:LEaut any of these specimens are referable to Q. cibollansis.
Superfamily Trionychoidea Gray, 1870
Family Trionychidae Bell, 1828
cf. Genus Platypeltis Fitzinger, 18??

Age and Distribution: Cretaceous to Recent of Asia,

2X'fzrica, North America, and Europe.

 

Type Species: Platypeltis ferox Schneider, 1783
cf. Platypeltis sp. indet.

Material: UM 98775m— most of the carapace and plastron,

C2<311ected at 88069, June 30, 1991. UM 100135- most of the

CIExrapace and plastron, collected at 88074, July 25, 1992.

Remarks: This genus has been tentatively recognized on
‘tihe basis of the pattern of the markings on the carapace.
'IThe markings are finer and more detailed than in the larger

‘trrionychid genera Apra and Aspiderites. In addition,

5several carinae run the length of the carapace, a feature

rlot usually seen in other trionychid genera. Both specimens

Eire juveniles however. Bartels (pers. comm.) feels that the

(Zarinae may disappear and the markings may become more

generalized with age.

Genus and Species indet.
Maparial: UM 95602m— seventh right costal, collected

at 88036, June 5, 1990. UM 98668m— carapace fragments,

collected at 88013, June 25, 1991. UM 98695m- carapace

fragment, collected at 88013w, June 28, 1991. UM 98704-

54

carapace and plastron fragments (at least two species),
collected at 88072, June 28, 1991. UM 98713m- carapace
fragments, collected at 88073, June 29, 1991. UM 98716—
carapace and plastron fragments, collected at 88070, June
29, 1991. UM 98722m- carapace fragment, collected at
88074, June 29, 1991. UM 987253- carapace and plastron
fragments, collected at 88070, June 28, 1991. UM 99634m-
carapace fragments, collected at 88097, June 17, 1992. UM
101015m- carapace fragment, collected at 88116, July 31,
1993. UM 101097m- carapace and plastron fragments (two or
three species), collected at 88118, August 5, 1993.

Ramarka: Although fragments of trionychid turtles are
common in the upper beds of the study area, more complete
specimens are rare. The plastron and carapace, and the
individual elements of the plastron are connected only by
ligaments facilitating rapid dispersal of the skeleton after
degradation. The highly varied sculpture patterns on the
surfaces of the carapace and plastron fragments in the study
collection indicate the presence of several different taxa.

Family Dermatemydidae Gray, 1870
Genus Baptapys Leidy, 1870

Aga app Distribution: Eocene (Wa?—Ui2) of North

America.

Typa Spepies: Qappapya,pypminganai§ Leidy, 1870

55
Baptemys fluviatilis Hay, 1908

Holotype: Hay (1908) described the species based on a
specimen donated to the American Museum, from an uncertain
level and locality, and did not give the holotype a
catalogue number.

Material: UM 99628- Nearly complete carapace, and
complete plastron and associated postcrania, collected at
88067. UM 99928- Complete plastron and carapace. Collected
at 88013,

Remarks: Hay (1908) recorded three species of
Qappapya. UM 99628 and UM 99928 are most similar to the
diagram and description of Q. fluviatalis in having a small
entoplastron, only two suprapygals, and a somewhat rounded
xiphiplastra. Q. pyomingenais is characterized by three
suprapygals, a large entoplastron, and blunt xiphiplastra.
Q. pricaripapa is characterized by having two suprapygals, a
large entoplastron, acute xiphiplastra, and as the name
suggests, three prominent ridges (or carinae) running the
length of the carapace. In both specimens the articulation
between the plastron and the carapace is well-fused, such
that the sutures are difficult to define. The scute
impressions are indistinct, indicating that both were older
animals.

Baptapys sp. indet.
Material: UM 95603— plastron fragments, collected at

88013, June 5, 1990. UM 95604m- carapace and plastron

56
fragments, collected at 88013, June 5, 1990. UM 95613m—
carapace fragments, collected at 88038, June 5, 1990. UM
95670m— carapace and plastron fragments, collected at 88051,
June 15, 1990. UM 98696— carapace fragments, collected at
88070, June 28, 1991.

Remarks: The material referred here is too incomplete
to assign to a particular Qappapya species. While all of
the specimens are comprised of fragmented carapaces and
plastrons, the neurals and peripherals included in the

specimens are identical in all respects to similar elements

in the two specimens referred to Qappapya fluviapalis (see
above). In addition, the texture of the dorsal surface of

the carapace fragments is unlike that of any other turtle
from the field area.
Family Carettochelyidae Lydekker, 1887

Genus Anpapaira Leidy, 1871

Typa Qpecies: Anpspaire pppapa Leidy, 1871

Aga apg Dispripatiop: Middle Eocene (8r1-8r3) of
wyoming, lower Oligocene (Suevian) of England.

Angageira pppapa Leidy, 1871

leopypa: Original holotype lost; the neotype is USNM
4062, a partial carapace and plastron from the lower Bridger
Formation near Fort Bridger, Wyoming.

Material: UM 955953- sixth peripheral and a fragment
of the epiplastron, collected at 88035, June 4, 1993. UM

956123- ninth peripheral, collected at 88037, June 5, 1990.

57
UM 99635mr carapace fragment, collected at 88037, June 17,
1992. UM 101026— sixth peripheral, collected at 88038,
August 1, 1993.

Remarks: Specimens of Anosteira ornate have been
collected from three localities within the study area, all
from the same level. Cope (1872) named A. raQulina, the
only other North American species, based on two peripherals
found near the present study area. The species was
diagnosed by it's much larger size than known specimens of
A. pppapa. Hay (1908) revised Cope's diagnosis, and based
the species on the more rhomboid shape of the anterior
peripherals. Bartels (pers. comm.) does not consider that
the known material warrants two species of this poorly known
genus.

Appapaipa pppapa is characterized by its uniquely
textured carapace and plastron. The sculpturing is in the
form of tiny, well defined tubercles rather than the broader
ridges and pits of the Trionychidae. The specimens from
within the study area are slightly larger than specimens of
A. papapa and much smaller than those of A. pagpiipa

measured by Hay (1908). The shape of the individual

peripherals matches those of A. anapa figured by Hay.

58
Order SQUAMATA Oppel, 1811
Suborder Lacertilia Cuvier, 1842
Infraorder Iguania Cuvier, 1807
Family Iguanidae Gray, 1825
Genus Paraaaurpmalua Gilmore, 1928

Aga apa Distribution: Middle Eocene (8r1-8r3? ) of
North America.

Typa Species: Parasauromalus olseni Gilmore, 1928.

Parasauromalus olaeni Gilmore, 1928.

Holppype: AMNH 1620- right dentary with five complete
teeth, and the basal portion of eight others, collected from
the Wind River Formation (early-middle Eocene), Alkali
Creek, Fremont County, wyoming.

Maparial: UM 98657— fragment of anterior portion of
right dentary with three teeth, collected at 88013, June 25,
1991. UM 98658— fragment of right dentary with three
complete teeth, collected at 88013, June 25, 1991.

Ramarka: Consistent with the diagnosis of Gilmore
(1928), UM 98657 and UM 98658 have pleurodont, laterally
compressed teeth. UM 98657 is a fragment of the anterior
part of the dentary and has less distinctly tricuspid teeth
than UM 98658. The crowns of the teeth are elongate,

reflected slightly inward, and are somewhat "spoon—shaped".

59
Infraorder Anguimorpha Furbringer, 1900
Superfamily Anguioidea Fitzinger, 1826
Family Anguidae Gray, 1825
Subfamily Glyptosaurinae Marsh, 1872
Remarks: Sullivan (1979) split the Glyptosaurinae into
two tribes, the Glyptosaurini and the Melanosaurini, both of
which are known from the study area.
Tribe Glyptosaurini Sullivan, 1979
Genus Glyptosaupas Marsh, 1871
Holopype: Qlypppaaarus aylvaspria Marsh, 1871
Aga apg Distribution: Late early Eocene (Wa6) through

early Late Eocene (Ui2) of North America.

Qiypppaaapaa sylvaatris Marsh, 1871
Qpippypa: USNM 16523- left frontal, collected from the

middle Eocene Bridger Formation at Grizzly Buttes (8r2),
Uinta County, wyoming.

Maparial: UM 98724- right frontal, six vertebrae and
additional vertebral fragments, limb fragments, collected at
88074, June 29, 1991.

Ramarks: This was the first fossil anguid lizard genus
to be described from North America. Marsh (1871) based his
description of Glypppaaurua aylveappia on a variety of
skeletal and cranial material including a "ventral
shield...covered with small polished tubercles", "a left
frontal", and a "fragment of jaw bearing three teeth"

collected from the middle Bridger beds (Bridger 8) near

60
Grizzly Buttes, Wyoming (Marsh, 1871, p.456). Gilmore
(1928) questioned the association of the other material and
limited the type to the left frontal. The frontal is
covered with primarily hexagonal osteoderms. Sullivan
(1979) limited the species included in Glyptosaurus to Q.
enlarge-‘12.

The right frontal of UM 98724 is identical in most
respects to the type described in Marsh (1871a) and other
specimens in Gilmore (1928). It is covered with discrete
hexagonal osteoderms. Consistent with the diagnosis of
Sullivan (1979) the osteoderms are strongly fused to the
underlying bone. Each osteoderm is covered with tiny raised
tubercles arranged in a concentric pattern.

Qiypppaaapaa is the only large lizard known from the
study area. Although the postcranial elements of the
various glyptosaurines are not useful in generic
identification, those associated with UM 98724 do indicate
the animal was large (30-50cm in total length), supporting
the diagnosis of the specimen as Glyptoaaupaa ayiypappia.

Glyptosaurini indet.

Maperial: UM 94890- one large vertebra, collected at
88019, June 29, 1989. UM 98574- isolated osteoscute,
collected at 88037, June 20, 1991. UM 98691— isolated
osteoscute, collected at 88013w, June 28, 1991. UM 98697-
associated vertebrae, collected at 88070, June 27, 1991. UM

98726m- isolated vertebrae and osteoscutes, collected at

61

88074, June 29, 1993. UM 99634- isolated osteoscute,
collected at 88097, June 19, 1992. UM 100898- one large
vertebra, collected at 88115, July 25, 1993. UM 101011-
isolated osteoscute, collected at 88114, July 31, 1993. UM
101013- isolated osteoscute, collected at 88116, August 1,
1993. UM 101034m- eight large vertebrae, collected at
88013, August 1, 1993.

Remarks: Isolated postcranial elements have not been
used in separating the various glyptosaurine taxa (see
Sullivan, 1979; Gilmore, 1928). Osteoscutes with raised

tubercles arranged in concentric rings are characteristic of

most glyptosaurine lizards (Sullivan, 1979). The presence
of Qiypapaaapaa aylvespria at the Desertion Point level (see

below) suggests that other glyptosaurine specimens,
especially those from the same level, may belong to this
taxon.
Tribe Melanosaurini Sullivan, 1979
Genus Qaapppa Cope, 1873

Aga apQ Distripppion: Eocene of North America.

Ramarks: The genus Xestops is indicated by the
presence of isolated osteoscutes from several localities.
The osteoscutes are covered with tiny tubercles and have a
diagonal keel across their entire length. They are slightly
thinner than in Qiypppaaapaa, and in complete specimens are
bevelled on the anterior and lateral surfaces. This

arrangement allows for free movement of the armour in three

62
directions (Hecht, 1959). The diagonal keel suggests an
angular rather than straight arrangement of the osteoscutes
as in Qlyptoseurus (Hecht, 1959).
Qaapppa cf. Q. vegans Marsh, 1873

Holotype: YPM 541- left and right dentaries, frontals,
basal portion of right coronoid, fragment of Pterygoid with
teeth, and numerous osteoscutes, collected from the Middle
Eocene Bridger Formation at Grizzly Buttes (8r2), Uinta
County, Wyoming.

Maperial: UM 101167- fragment of the right dentary
with four teeth, a single caudal vertebra, and 58
osteoscutes, collected at 88110, August 5, 1993.

Remarks: UM 101167 is the remains of a tiny, possibly
juvenile individual. The teeth are pleurodont and simple.
Consistent with the description of Gilmore (1928), and that
of the type (Marsh, 1872), the teeth are rodlike with obtuse
crowns. The tips of the teeth are pigmented, possibly an
artifact of preservation since other specimens referred to
this species are unpigmented. The osteoscutes are typical
Qaapppa osteoscutes (see above). The vertebra is abraded
and is not diagnostic.

Tpr Spegies: Qaappp§,yagap§ Marsh, 1873

Xastppa sp. indet.
Qapapiai: UM 95612m- isolated osteoscute, collected at

88037, June 5, 1990. UM 98655- isolated osteoscute,

collected at 88013, June 25, 1991. UM 98667- isolated

63
osteoscute, collected at 88013, June 25, 1991. UM 98695-
isolated vertebrae and osteoscute, collected at 88013w, June
29, 1991. UM 98719- isolated osteoscute, collected at
88074, June 29, 1991. UM 98744- three osteoscutes,
collected at 88069, June 30, 1991.

Remarks: Species of Xestops are difficult to identify
from isolated vertebrae and osteoscutes. Although Kestpps
vegans is present in the study area, and is ubiquitous in
the Bridgerian of the Bridger Basin, the material is

insufficient to warrant specific identification.

Suborder Serpentes Linnaeus, 1758
Family Boidae
Subfamily Erycinae Hofstetter and Rage, 1972

Remarks: Hofstetter resurrected the subfamily Erycinae
on the basis of the unique osteological characteristics of
the caudal vertebrae (Hecht, 1959, Holman, 1979). This
group of fossorial to semi—fossorial boids is thought to
have originated in the "North America-Western European"
geographic unit and migrated to Asia and Africa from there
(Holman, 1979).

Genus Qaiapagpaa Cope, 1873

Aga apg Qiapribapion: The genus Qaiapagpaa is known

from the middle Eocene through the middle Miocene of North

America and the lower Eocene of France.

Typa Spacies: Qaiapagpaa parivopaa Cope (1873)

64

Holotype: AMNH-1603- six articulated trunk vertebrate,
collected in the middle Oligocene Oreodon beds at Cedar
Creek, Colorado.

Remarks: Vertebrae of individuals of this genus are
characterized by a comparatively short centrum, a short,
stout neural spine, and a low, wide neural arch. The
zygapophyses are joined by a low, short ridge, the glenoid
fossa is suboval, and the condyle is moderately oblique
(Gilmore, 1938).

The genus Celapagrea is closely related to the North

American genus ngpphis and may in fact be congeneric (Rage,
1977; Holman, 1979; Gilmore, 1938). The only feature used

to distinguish between the two genera is the neural spine
which is short and thick in Qelemagraa, and thin and
elongate in Qgppppia (Holman, 1979, Rage, 1977). Rage (1977)
feels this criterion is invalid since the length of the
neural spine of snake vertebrae varies throughout the
vertebral column. This character does not vary appreciably
in modern erycinine boids however (Holman, pers. comm.). and
is considered here to be a diagnostic character.
Qaiapagpaa primus Hecht, 1959

Holppype: AMNH 3828- a single trunk vertebra, collected
in the middle Eocene Bridger Formation near Tabernacle Butte
in the northeastern Green River Basin, Wyoming.

Maparial: UM 101211- Two vertebrae, collected at 88037

on June 5, 1992.

 

65

Remarks: UM 101211 (Figure 6) is the only fossil snake
specimen recovered from within the study area. The specimen
agrees well with the description and illustrations of Hecht
(1959) and Holman (1979) in having a relatively short, thick
centrum with a low although distinct haemal keel, a
trapezoidal neural canal, and a well-rounded, ovaloid
condyle which extends directly posteriorly. The zygosphene
is thin and high. The neural arch, although broken off, was
thick at the base.

Suborder Amphisbaenia Gray, 1844
Family indet.

Matarial: UM 101168— Fused centra of the atlas and
axis, collected at 88110, August 5, 1993.

Ramarks: UM 101168 is the only amphisbaenid specimen
recovered from within the field area. This element has a
single elongate dorsal keel, unlike the interrupted dorsal

keel found in most lizards.

 

A.
B.
C.
Figure 6. Trunk vertebra of Calamagraa primua (UM
101211). Bars are one millimeter in length.

A. anterior view. 8. dorsal view. C. lateral
view.

67
Subclass Archosauria Cope, 1891
Order CROCODYLIA (Gmelin, 1789)
Suborder Eusuchia Mook, 1934
Family Alligatoridae (Cuvier, 1807)
Genus Allogpathosuchus Mook, 1921
Aga apa Distribution: Palaeocene and Eocene of Europe
and North America.
Typa Species: Allogpaphosuchus polyodon (Cope, 1873)

Allogpathosuchus sp. indet.
Maperial: UM 95595m- isolated tooth, collected at

88035, June 4, 1990. UM 95613m- isolated tooth, collected
at 88038, June 5, 1990. UM 98695m- isolated tooth,
collected at 88013w, June 28, 1991. UM 98735m— isolated
tooth, collected at 88077, June 29, 1991. UM 100892- six
teeth, collected at 88114, July 25, 1993.

Ramarka: The teeth of Allogpaphogughas are unique among
crocodilians in the study area. They are somewhat onion-
shaped, slightly laterally compressed, and have tiny,
slightly wavy striae running vertically from the flat
occlusal surface to the base of the enamel (see figure 7).
Case (1925) considered.Aiipgpapppaappaa to be a
molluscivore, but Bartels (1984) and Simpson (1930) argued
for a varied diet.

Genus Dipippypodpn Pomel, 1843
Aga apg Dispribution: Eocene of North America, Eocene

through Pliocene of Europe.

68

Type Species; Diplocypodon retelli

Diplocypodon sp. indet.

Material: UM 95595m- isolated tooth, collected at
88035, June 4, 1990. UM 95613m— three teeth, collected at
88038, June 5, 1990. UM 98577m- two teeth, collected at
88037, June 20, 1991. UM 98713m- isolated tooth, collected
at 88073, June 28, 1991. UM 98733m- associated osteoscutes,
collected at 88012, June 29, 1991. UM 99638m- isolated
tooth, collected at 88074, June 18, 1992.

Remarka: Diplpcyppdon is known from the study area by
isolated teeth and osteoscutes. The teeth (Figure 7) are
long and gracile, and possess thin ridges from apex to base.
The teeth are similar to those of the extant crocodilian
Qayiaiia gapgapigaa (the Gharial) and are suggestive of a
piscivorous diet.

Diplpcyppgpn is tentatively placed within the
Alligatoridae, but may be more closely allied with caimans
or crocodylids (Bartels, pers comm.).

Genus and Species indet.

Maparial: UM 95601- cranial and skeletal fragments,
collected at 88036, June 5, 1990. UM 95612m— isolated
osteoscute, collected at 88037, June 5, 1990. UM 98692-
skeletal fragments, collected at 88013w, June 28, 1991. UM
98707- isolated quadratojugal, collected at 88073, June 28,

1991. UM 98731m- associated osteoscutes, collected at

69
313076, June 29, 1991. UM 98772- skeletal fragments,
collected at 88069, June 30, 1991.

Remarks: The osteoscutes of alligators are
differentiated from those of other crocodilians by
possessing sutures on both the lateral and the posterior
surfaces rather than just on the lateral. Three genera of
alligators have been reported from the Lower Bridger
Formation of southwestern Wyoming. Two of these,
W and Diplocmodon have been recovered from
the study area (see below); the other, Prpceimanoiaie, has
not: yet been recovered from the study area although it has
been reported from slightly higher strata adjoining the
Study area to the east (Gunnell and Bartels, in press).
Unfortunately the postcrania of these three genera are
difficult to distinguish.

Family Crocodylidae (Cuvier, 1807)
Genus ngppgyiaa Laurenti, 1768

App apg Diapripapion: Cretaceous to present of Asia,

South America, North America, Europe, Australia, and Africa.

Typa Spacias: Qrocpdylua nilotigus Laurenti, 1768.

Ma affinia Marsh, 1871
leopypa: YPM 1345- an almost complete skull and

mandibles, collected from the middle Eocene Bridger
ForItlation at Grizzly Buttes (8r2) , Uinta County, Wyoming.
Qatapigi: UM 95595m- isolated tooth, collected at

BB035, June 4, 1990. UM 95612m- isolated tooth, collected

70
at B8037, June 5, 1990. UM 98577m— two teeth, collected at
88037, June 20, 1991. UM 98579m- two teeth, collected at

88044, June 20, 1991. UM 98698m— tooth, vertebra, and

osteoscute, collected at 88070, June 28, 1991. UM 9871331—

isolated tooth, collected at 88073, June 28, 1991. UM
9872 8- seven teeth, collected at 88075, June 29, 1991. UM

9872 931- Tooth fragment, collected at 88076, June 29, 1991.

UM 9873313— isolated tooth, collected at 88012, June 29,
1991 . UM 9873513- two teeth, collected at 88077, June 29,
1991 . UM 9877513- two teeth and associated limb fragments,
collected at 88069, June 30, 1991. UM 99638m- isolated
tooth, collected at 88074, June 18, 1992. UM 9984413-
iSOlated tooth, collected at 38035, July 16, 1992. on
10089613— teeth and osteoscutes, collected at 88114, July 25,
1993 . UM 101170- two teeth, collected at 88110, August 5,
1993 .
Ramarka: The teeth of C_rcic_:prit_1_a m are among the

most common crocodilian remains within the study area. The
teeth are rather robust, only slightly laterally compressed,

and possess relatively straight striae from the tip to the

base - They are pointed, but quickly widen unlike the long
SleEider teeth of W (figure 7) . The teeth of Q.
W are the most generalized teeth of any of the Bridger

croCodilians. These teeth would be beneficial for crushing

bones, less so for tearing flesh. Q. ffini probably

 

nae!
d U

D-

7‘-
H

‘4

A
V;
V‘

71
prayed upon turtles, tetrapod herbivores and fish, perhaps
even large gars.
New genus (?) and species

Material: UM 95599- Complete skull and associated
postcrania, collected at 88013, June 28, 1991.

Remarka: Little can be said about this specimen as it
is still in preparation. It's snout is substantially
blunter than any of the described crocodilids from the field
area . The dentition indicates a generalized diet, similar
to that of Crpgodylus effinis

Family Pristichampsidae Kuhn, 1968
Genus PrispiQMsus Gervais, 1853

Ramarka: The taxonomic position of Pristic Bus is

rather uncertain. The teeth, and certain of the skeletal
elements are unlike those found in any other crocodilians
(Troxell, 1925; Langston, 1975; Bartels, pers. comm.).

“711i le dental occlusion is intermediate between that found in
Alligatoridae and that found in Crocodylidae (Langston,
1975 ) , the skull is morphologically most similar to
cI‘OCodilids. Langston (1975) and many previous authors
retained Priapippamsus in the Crocodylidae. This thesis
follows Kuhn (1968) in recognizing family Pristichampsidae

Aga aaa Diapribution: Eocene of Europe and North

America.

Me Qpacias: Pristichampaug mpg Troxell, 1925

an.
2"”-

3 v..<‘b‘ v-

 

an:
(II
(n

 

"‘ .3.-

a

.
up ‘

~ A l
in
.‘y‘ 5‘ '1

'§ 5‘

72

Pristicpappsus vorax Troxell, 1925
Holotype: YPM 249- crushed skull and mandibles,

 

fragmented skeleton, collected from the "Greensand
Formation" (lowest Bridger Formation) near Red Dog Butte
( Brl) in the Bridger Basin, Wyoming.

Matarial: UM 98712- tooth fragment, vertebra, and an
osteoscute, collected at 88073, June 28, 1991. UM 9857731—
1arge single tooth, collected at 88037, June 20, 1993.

Ramarks: Q. vorex is the only ziphodont (dinosaur—

toothed) crocodilian known from the Eocene of North America.

The teeth are unique among Cenozoic crocodilians. They are
Slightly curved, laterally compressed, and possess tiny
serrations on the anterior and posterior edges (figure 7) .
The teeth are set in the mandibles and the maxilla at an
aJingle, and are pointed posteriorly. The "?carnosaur tooth"
r$ported from the Bridger Formation at Opal Bench, 10 kms
1'IQrth of the study area by Wood (1966, p.54) is undoubtedly

representative of a large specimen of this enigmatic taxon.

Figure 7.

 

73

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B.

s

§

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3‘

C

\

\

l

I Ins
m"|(i..§
>‘I
"“‘lillulfl‘k
NUWHWHW'
«“0". '

   

llll

 

Crocodilian teeth. A. Allpgpathoauchua (UM
100892). 8. Diplpcypodon (UM 98577m). C.
Crocodylus effinis (UM 101012m). D.

Bars are

Pristicpappaus vprax (UM 98577m).

one millimeter in length.

74
Class Mammalia Linneaus, 1758
Infraclass Metatheria Huxley, 1880
Order DIDELPHIMORPHIA Illiger, 1811
Superfamily Didelphoidea Gray, 1821
Family Didelphidae Gray, 1821
Subfamily Didelphinae Gray, 1821
Tribe Didelphini Crochet, 1979
Genus Peretherium, Aymard, 1850

Aga apa Distribution: Early Eocene (Wal) to late
Oligocene (Arl) of western North America.

Typa Spacies: Q. comstocki Cope, 1884

Peretherium comstpcki Cope, 1884

leotype: AMNH 4252- left dentary fragment with M/2-
1‘II’3, from an unreported locality in the "badlands of the
Wind River, Wyoming" . I

Maparial: UM 95611- left dentary fragment with /M1

IDJETeserved, collected at 88037, June 5, 1990.

Ramarka: Parethariap mestpcki is by far the largest
bIcarth American species of Parapherium. UM 95611 is
ecauivalent in size to specimens of Q. conspogki from the
Vtind River Formation measured by Krishtalka and Stucky

(1983). Measurements of UM 95611 are provided in Table l.
Consistent with their description, the tooth has a strong,
although rather short, precingulum at the base of the

protoconid, the largest of the cusps. The paraconid, the

lowest of the trigonid cusps, is deflected anterodorsally.

-

75
CPIleE: entoconid is large and conical and separated from the
flat tabular hypoconulid by the entoconid notch, a gap in
the postcristid.
Peretherium innominetum Simpson, 1928
Holotype: AMNH 11493— Partial left dentary containing
/Ml-/M3, collected at Millersville from the Lower Bridger
E?c3c:nmation (Brl) in the Bridger Basin, Wyoming.
Material: UM 95610- fragment of left dentary containing
/1![]. and alveoli of /M2, collected at 88037, June 5, 1990.
till. 99919- talonid of right Mx/, collected at 88109, July 21,
19 92. UM 101102- right M2/, collected at 88118, August 5,
3.5!93.
Ramarks: Three specimens have been referred to
a9 rethapium innominetum. UM 95610 comes from one of the
hli1ghest localities in the section, while UM 101102 comes
153:?om.one of the lowest. UM 99919 was recovered from.one of
t11:1e intermediate beds in the section.
The teeth fall well below the size range of most
EEEQQaQQapiap species including Q. cometocki, also known from
IT—I‘ie study area (Table 1). The two exceptions are Q.

kn_ighpi, and Q. innominetum. Similar to described specimens

Of Q, innominapap and unlike those of Q. knighti (Krishtalka
and Stucky, 1983), UM 95610 possesses a low, posteriorly

projecting hypoconulid. The hypoconulid is separated by a
deep groove from a large entoconid. The entoconid and

hypoconid are tall and pointed resulting in a very deep

76
t:azJLonid basin, deeper than that exhibited in Q. knighti.
E>j.sssindlar to the condition in Q. knighti (Krishtalka and
Stucky, 1983), UM 101102 has a very distinct ectoflexus. UM
99919, although rather incomplete, is very similar to UM
].()214102.

Previously Bown (1982) and Setoguchi (1973) allocated
Pgrepharium innominetum to the genus Peredectes, a didelphid
Qgeeraus well known from higher Bridger Beds. Krishtalka and
£3t:11cky (1983) returned Q. innominatap to the genus

Pgrapherium on the basis of the size of the entoconid of /M2
£11121 [M3, and the presence of a deep, wide notch between the

entoconid and the hypoconulid (Krishtalka and Stucky, 1984) .

TABLE 1

Measurements (in mm.) of Marsupialia

Paraphariap
Q. o ms cki Q. innpminatap
. UM 95611 UM 99919
/M1 AP 2.7 1.9
Tra 1.3 0.8
Trp 1.5 0.7
UM 101102
M2/ AP 1.8
Tr 1.7

77
Infraclass Eutheria Huxley, 1880
Order INSECTIVORA Illiger, 1811
Suborder Proteutheria Romer, 1966
Superfamily Apatemyoidea Matthew, 1909
Family Apatemyidae Matthew, 1909
Apetapys Marsh, 1872
Aga apg Distribution: Late Palaeocene (Cfl) through
]_aat:e Eocene (Du) of North America

Typa Species: Apapapya paiiaiaa Marsh, 1872

cf. Apetapys sp. indet.

Material: UM 101022- right /I1, collected by at 88037,
ZXngust 1, 1993.

Remarka: Apatemyids, and Apetapys in particular are
Ciklaracterized by enlarged lower incisors (Marsh, 1872;
I”resetthew, 1915). Apapapya is the only apatemyid insectivore
13<52ported from the study area or adjacent strata. UM 101022
5‘53; somewhat smaller than the type of A. bellus measured by
DIiEirsh (1872), and may belong to A” bellulua. Measurements
C>1E specimen UM 101022 are provided in Table 2.

Family Pantolestidae Cope, 1884

Genus Qaiaapaipppa Matthew, 1901
Aga apg Diapripation: Late Palaeocene (Ti4) to middle

Eocene (Brl) of North America, and possibly the early Eocene

of eastern Asia.

Type Species: Palaeoainppa veterrime Matthew, 1901.

 

 

78

Peleeoainopa cf. Q. lutreola Matthew, 1918

Holotype: AMNH 15100- fragment of right dentary with

,/WJM2 and /M3, from the lower beds of the Willwood Formation

253.1t Elk Creek, Bighorn Basin, Wyoming.

Material: UM 101155— right M2/ with abraded metastyle

arid postcingulum, collected at 88110, August 5, 1993.

Remarks: UM 101155 is characterized by its prominent

1;»2aarastyle wing, extending far out from the paracone. The

precingulum is slight, and only extends from the lingual

sstciie of the protocone to the paraconule. The metaconule is

rueazaerly imperceptible.

Although morphologically similar, the tooth is

cc>xtesiderably smaller than specimens of Peleapsinope

W and Q. inperpa figured in Bown and Schankler

(1.5?132). The specimen is possibly referable to Q. iappapia

luivaeaver this species is known from the lower dentition only

(‘76111 valen, 1967). Measurements of specimen UM 101155 are

Provided in Table 2.
Family Lepticidae Gill, 1872
Subfamily Lepticinae Gill, 1872
Peleaiptopa Matthew, 1899
Aga apQ Dispribution: Early to late Eocene

(Wa3-Ui2) of
Wes tern North America .

Type Qpecies: Peleeicpppa bigaapis (Cope, 1880)

79
Peleeictops bicuspis (Cope, 1880)

Holotype: AMNH 4802- crushed skull and mandibles with
nearly complete dentition, collected from the Lost Cabin
beds (Wa7) of the Wind River Basin, Wyoming.

Material: UM 101166— left /M2, collected at 88110,
August 5, 1993.

Remarks: UM 101166 (Figure 8) is the only leptictid
identified from within the study area. Although the
trigonid is wider than the talonid, the talonid basin is
much larger and deeper than the trigonid basin. The
hypoconulid extends posteriorly from the postcristid. The
paraconid is centrally placed and projects farther
anteriorly than in the closely related Peleaicpppg brngari.
The paralophid descends quite low between the paraconid and
the protoconid unlike the even ridge present in Q. bridgari.

The tooth is considerably larger than specimens of Q.
paapi-Qinarai reported by Jepsen (1930), and specimens of Q.
pineyanaia reported by Gazin (1962) and Guthrie (1967). It
is smaller than the few known specimens of Q. pulpipaspia
reported by Guthrie (1971), and slightly smaller than the
type of Q. prngari described by Simpson (1959). UM 101155
is similar in size and morphology to the smallest specimens
of Q, pigaapia reported by Guthrie (1967). Measurements of

specimen UM 101155 are provided in Table 2.

80

 

 

A.
8.

Figure 8. Palaaictops bicuspis. A. Occlusal view
of /M2 (UM 101166) B. Labial view of /M2
(UM 101166). Bar is one millimeter in

length.

81
Suborder Erinaceota Van Valen, 1967
Superfamily Erinaceoidea Fischer von Waldheim, 1817
Family Dormaliidae
Genus chnopagas McKenna and Simpson, 1959

Typa Species: Scenopegas edenensis (McGrew, 1959)

Aga apQ Dispribution: Early to late Eocene (Wal—Uil) of
North America.

2222212212! 222m; (McGrew, 1959)

Holotype: AMNH 55685- fragment right mandible with /M1—
/M3, collected from the Morrow Creek Member (Brl) of the
Green River Formation, Eden Valley, Wyoming.

Material: UM 101019- fragment of left dentary with
/M2, collected at 88037, August 1, 1993.

Remarks: McGrew (1959) originally referred Q.
agapapaia to the genus Diacpaon. Later that same year and
with material from the same area McKenna and Simpson (1959)
described a new genus, Q. mcgrewi. In 1962, McKenna et a1
referred Q. aQanansis to the genus Qcanppegas recognizing

the priority of Q. edenenais over Q. mcgrewi.

Judging from the amount of wear, UM 101019 is a
specimen of relatively old individual of Q. edenanaia.
Consistent with the description of McGrew (1959), the
trigonid is inclined forward and is slightly wider than the
talonid. The trigonid basin is tiny compared to the large
talonid. The ridge between the hypoconid and the base of

the protoconid is quite prominent. The tooth is much larger

82
than specimens of Q. priscus measured by Robinson (1966).
It is similar in size to the type of Q. edenensis (McGrew,
1959) and with specimens reported by Robinson (1966) and
West (1973). Measurements of specimen UM 101019 are
provided in Table 2.
Qgenopegas priscus (Marsh, 1872)

Holotype: YPM 15309- left dentary with /M2 and alveoli
of /P4, /M1, and /M3, from the middle Eocene Bridger
Formation (8r2) near the Henry's Fork River, Wyoming.

Material: UM 95608- fragment of right dentary with
/Ml—/M2, collected at 88037, June 5, 1990. UM 95609-
fragment of left dentary with /P1-/P3, and both dental
foramina, collected at 88037, June 5, 1990.

Remarka: Robinson (1966) reassigned chpipharium
priagua to the genus chnppegas based on its similarities to
Q. agapapaia and its dissimilarity to Q. yaipp. Two
specimens from the study area have been referred to
22222222222—2211'1 11-

The two molars of UM 95608 are very nearly equal in
size. On both teeth, the hypoconulid extends posteriorly
from the postcristid. The trigonid and talonid of /M1 are
approximately equal in size, while the trigonid is slightly
narrower than the talonid in /M2. The trigonid is directed
slightly anteriorly.

Anterior premolars in Qaapppagaa have not been

described for some species and are difficult to refer to a

/P1
/P2

/P3

/M1

/M2

83

Table 2

Measurements (in mm.) of Insectivora

Apetepys sp. indet.

UM 101022
/I1 AP 1.6
Tr 1.2

Peleeosinope cf. Q. lutreole

UM 101155
M2/ AP 2.4
Tr 4.6

Pelaeictops biguspis

UM 101166
/M2 AP 2.8

Tra 1.9

Trp 1.7

cnoes

Q. adenansis Q. prisgus

UM 101019 UM 95609
AP - 0.7
Tr - 0.3
AP - 1.2
Tr — 0.4
AP - 1.1
Tr - 0.5

UM 95608
AP - 1.8
Tra - 1.5
Trp — 1.3
AP 2.1 1.6
Tra 1.7 1.2
Trp 1.4 1.1

84
particular form. UM 95609 falls well below the expected

size range of Q. edenensis and is close to that of Q.

priagas.

The two specimens are consistent with specimens of Q.

ppiaaaa and much smaller than specimens of Q. adenensis
described by Robinson (1966) and West (1973). Measurements

of specimens UM 95608 and UM 95609 are provided in Table 2.
Insectivore indet. '

Material: UM 101014- left astragalus, collected at
88116, July 28, 1993. UM 101160— fragment of edentulous
right dentary with alveoli of /P4-/M1, collected at 88110,
August 5, 1993. UM 101161- fragment of right dentary with
roots of /M1, collected at 88110, August 5, 1993. UM
101164- fragment of upper molar, collected at 88110, August

5, 1993.

Order PROPRIMATES Gingerich, 1989
Suborder Plesiadapiformes Simons and Tattersall, 1972
Remarka: The plesiadapiforms are the earliest group of

primate-like animals known. Although plesiadapiforms have
traditionally been included in the Order Primates, the
relationship of the plesiadapiform primates to early Eocene
primates of modern aspect has always been somewhat
conjectural. Gunnell (1989) established that
plesiadapiforms are more closely related to plagiomenids

(archaic denmopterans) than to true primates. Gingerich

A.

w.

b.‘_'

85

(1989) proposed the name Proprimates to include two
Superfamilies (Microsyopidae and Plesiadapoidea), separating
them from the more advanced primates and recognizing that
this is likely a paraphyletic grouping.

Superfamily Plesiadapoidea Trouessart, 1879

Family Paromomyidae (Simpson, 1940)
Tribe Paromomyini Simpson, 1940
Genus Igpecius Matthew and Granger, 1921

Aga apQ Distribution: Middle Palaeocene (T03) to late.
Eocene (Ui2) of the Rocky Mountain Region of North America.

Typa Qpapiaa: 12822182 fpagivorpas Matthew and Granger,
1921.

Tapapiaa greybullienus Bown and Rose, 1976

Holotype: YPM 26004— fragment of right maxilla
containing P4/ to M2/, lower Willwood formation, Big Horn
County, wyoming.

Maparial: UM 101154- right M2/, collected at 88110,
August 5, 1993.

Ramarka: UM 101154 (Figure 9) is identical in size to
the type of Igpaciua greypallienus described and figured in
Bown and Rose (1976). Similar to all of the specimens
studied by Bown and Rose (1976) the posterolingual corner of
the tooth is much less rounded than in T, giggiypppaa.
Although the tip of the parastyle wing has been sheared off,
it appears to have been larger than in the type of T.

greybullienpa. In addition, the tooth possesses a more

86
developed lingual precingulum than the type. The tooth is
slightly wider labially than lingually, giving it a less
squared appearance than in the type.

Although there are some minor morphological
differences, they are not considered substantive enough to
warrant allocation to a new species without the study of
additional material. Measurements of specimen UM 101154 are
provided in Table 3.

Superfamily Microsyopoidea Osborn and Wortman, 1892
Family Microsyopidae Osborn and Wortman, 1892
Subfamily Microsyopinae Osborn and Wortman, 1892

Remarks: The upper cheek teeth of early microsyopines
are characterized by the complete lack of a stylar shelf.
The cusps of the cheek teeth are low, the talonid basin is
comparatively deep. They typically have a single pair of
enlarged upper and at least one pair of enlarged lower
incisors. A small diastema, usually not exceeding the first
cheek tooth in length, exists between the enlarged incisors
and the cheek teeth. The incisors often display
considerable wear on the medial surface, a product of a
rather unique method of mastication (Gunnell, 1989) (see
below). A single microsyopine incisor is generally
considered sufficient for identification to the subfamily

level.

87

 

F igure 9 .

Igpacius graybullianus. Occlusal view of
M2/ (UM 101154). '
length.

Bar is one millimeter in

Genus Microsyops Leidy, 1872
Age and Distribution: Known primarily from the early
exnd middle Eocene of Wyoming, Colorado,

and New Mexico.

The
sgenus is first known from the latest Palaeocene

(Cf2) of the
Bighorn Basin (Woodburne, 1987) and last known from a single
specimen from the middle Eocene (Ui2) Friars Formation in
California.

Type Species: Microsyops elegans Marsh,

1871
Microsyops elegans Marsh,

1871
Holotype:

YPM 11794- left dentary containing /P4-/M2,
collected from lower Bridger beds,

Bridger Basin, Wyoming.
Specific locality data is unavailable.
Material:

UM 99843- Cranial material including a skull
roof with parietals, frontals,

the occipital complex, and

i I

ve

Ea

3“

~x~

88
the right petrosal; a right maxilla including P4/, M1/, and

the labial half of M2/; a right dentary including /P3

through /M1, sheared /I3, intermandibular suture, masseteric
ft:se;.eesta, and mandibular condyle; fragments of a left dentary
ir1<:::1_‘uding labial half of /P4, mental foramen, and the
mandibular condyle. Several rib fragments fit the expected
size range for microsyopids and may belong to the same
lirlditi_cvidual as the cranium, collected at 88036, July 16,
1992 . UM 101032— left /M1, collected at 88013, August 1,
3.S>S>:3..
Remarks: Most specimens of pigpgaygpa aiagapa are from
ltrlei lower Bridger beds (8r1-Br2) of southwestern wyoming
(E353ialay, 1969). The /P4 of UM 99843 has a broad talonid
has in and a centrally placed hypoconulid similar to
W agoppianas, a. alagens, a. knightoagig, and to
:LEitzer specimens of Q. lapidana, however, the measurements of
/F*4 and /M1 fall considerably above the size range of Q.
lfiksigapg. Additionally, the protoconid of both /P4 and /M1
ifloes not extend as high above the talonid as those of
Specimens of Q. lepigana studied by Szalay (1969).
The cheek teeth of UM 99843, particularly /M1, /M2, and
/P3 fall well below the size range of Qigpgayppa agpppiapaa
but are within the size range of both Q. elegana and Q.
knighpansia. Gunnell (1989) indicates that these two species
could be considered conspecific since only a few minor

differences are present. Most importantly, UM 99843 appears

89
to have the more strongly dilambdodont upper molars of M.
w, and has more slender mandibles than M. knightenais.

The skull of Microsxons is known from three described

specimens, two skulls and a skull fragment (Szalay, 1969,

Gunnell, pers. com, 1992). Of these three specimens, only

one , AMNH 55286 has the otic region intact. UM 99843

therefore comprises the most complete cranial material of M.

eleggg known.

Microsyopid postcranial osteology is even less well

known. The only definite postcranial element of a

microsyopid is a proximal tibia associated with upper teeth

Of g. ESL-EM from the lower Bridger beds. UM 99843

includes several rib fragments that were found in close

association with the teeth and skull fragments and fit the

expected size range of microsyopids. Two metatarsals and a

calcaneum were catalogued with the specimen but are not

included here since they are much too large to have come

from a microsyopid. Measurements of specimens UM 99843 and

UM 101032 are provided in Table 3.

Migrgsxons scattianus Cope, 1881

m: AMNH 4748- left mandible with /P4 and part of
/M2 ,

Collected from the Lost Cabin Member of the Wind River

FOrmation, Wind River Basin, Wyoming.

W cf. M. scotgianaa Cope, 1881

Magarial: UM 100888— left dP4/, collected at BB114,

July 25, 1993.

9O
Remarks: UM 100888 is larger than P4/ in Microsygps

knighaensig and Microsyops latidens and is slightly smaller

than M. M described in Gunnell (1989) . This specimen

is; tzentatively referred to M. scottianus, primarily on the
135155.jLs of size, since morphological variation in deciduous
Ipxrealnmolars is not considered diagnostic. Measurements of UM
100888 are provided in Table 3.

Microsxpps sp. indet.

Material: UM 99636- Edentulous left mandible
C>C)rlsisting of the ramus of the dentary from /I3 socket to
/TE>ES socket; intermandibular symphysis present, collected at
BBO74, June 18, 1992. UM 99720- Fragment of upper left
<2]:Leeek.tooth.(probably P3/), collected at BBO74, June 29,
21:5’591.

Ramarka: Although all of the teeth are broken off of
tnfll 99636, enough of the socket and root exist to indicate
the presence of an enlarged lower incisor, an important

Ckléinracter in microsyopines. As is also characteristic of
mi<Zrosyop-ines, the specimen has an unfused mandibular
Skfimqphysis. It is thought that the mandibles were movable
(hxrfiing mastication, as is evidenced by the wear facets on

UhEE medial surface of the enlarged lower incisors (Szalay,

1969).
Specimen UM 99636 is somewhat dissimilar to most
Eisgggxgng mandibles in having two mental foramina on the

labial side of the ramus rather than the usual single one.

 

 

91
The first of these foramina is located below the diastema
between the enlarged lower incisor and /P2, the second is
located in the usual position under and slightly forward of
/P3 - A third foramen is located below, and slightly caudal
to /M1.

Other closely related taxa such as Crasaopg and
Arggggontgms have twin mental foramina. Microsyops is the
only microsyopine known from the late Wasatchian (Wa7) or
early Bridgerian (Brl) of western North America. The only
Species of Micrgsxops known to have multiple mental foramina
is the middle Eocene M. kratos, known from a single specimen
from California, which has two foramina under dP3 (Gunnell,
1 9 89) .

UM 98720, although worn and incomplete, has several key
Characteristics of the genus Migrosxons (e.g., a small but

pronounced metaconule lingual to the metacone and a

me sostyle between the paracone and metacone) . Microgxgng
W is the only species of the genus known from the

1O‘Mer Bridger beds of Wyoming (Szalay, 1969) , but the
referred specimens are not complete enough to identify to

the specific level.

Ml/
/P3
/P4
/M1

/M2

AP
Tr
Ap
Tr
Ap
Tr
AP
Tr
AP
Tr

92

TABLE 3

Measurements (in mm.) of Proprimates

Igaacius graxbullianas

UM 101154
M2/ AP 2.2
Tr 2.7

Migrosxops e1egans

UM 99843 UM 98664 UM 101032
3.9 - -
4.3 - -
2.4 - -
1.6 - —
3.8 - -
2.5 — —
4.0 - 4.1
2.4 - 2.9

93
Order PRIMATES Linneaus, 1758
Suborder Haplorhini Pocock, 1918

Infraorder Adapiformes Szalay and Delson, 1979

Family Adapidae Trousseart, 1879

Subfamily Notharctinae Trousseart, 1879

Remarks: Four of the five notharctine genera have been

Ireecz<3vered from within the field area. Two of these,

fimilogectes and Ngtharctus are first known from the early

Br idgerian. The other two, Copelemur and Cantius are last

L:r1<ywn.from the late Wasatchian.

Tribe Notharctini (Trouessart, 1879)

Ramarks: Beard (1988) resurrected the tribe

Iflk:>t:harctini and established the tribe Copelemurini (see
below) to distinguish the two monophyletic groups within the

No tharctinae .

Genus Cantius Simons, 1962

Aga ang Distribution: Early Eocene (WaO to Wa4,

Neustrian) of Europe and North America.
,Iypa figagiaa: gantiag angalatus Cope, 1875

Ramarks: The early Eocene notharctine Qantius is the

earliest known lemuriform primate (Rose, 1981, Rose and

VW31J<er, 1985) and is considered ancestral to other Eocene

notharctines such as Ngtlaarctua and gmilodectas (Rose and

‘Malker, 1985, Gingerich and.Simons, 1977, Szalay and Delson,
1979). Most adapids from the early Eocene of North America

are known from scant material and for many years all were

94

included in a single genus, Pelycodus (Rose and Walker,

19 8 5, Szalay and Delson, 1979) . Gingerich and Simons (1977)

es tablished the genus Copelemur to include several species

wi 1:11 markedly different molar morphology than Pelxcodus.

Gingerich and Haskin (1981) limited Pelycodus to the type

species, g. jarrovii, since the dentition of g. jarrgvii is
substantially different than that of other, previously

included taxa, and reinstated the genus Cantius

1962)

(Simons,
to include all other species that had previously been

r e f erred to Pelxcodus .

Qantius frugivorous (Cope, 1875)
Holotype: unnumbered fragment of right dentary with

/M2 and /M3 from the San Jose Formation (Wa3-Wa4) , San Juan

Basin, New Mexico, now lost. The neotype is CM 37448— right

dentary fragment with /M2 and /M3 from the "Alamagre

locality 2", New Mexico.

Qaatiaa cf. Q. frugivoraag

Material: UM 100021~ left M2/, collected at BBllO, July

2'7.. 1992. on 100025- right /M1, collected at 33110, July

27'. 1992. on 100026- right M3/, collected at 33110, July
27'. 1992. on 101096- right /M3, collected at 33114, July 31,

1~993. UM 101162- left /M2, collected at BB110, August 5,
1993.

Remarks: Five individual teeth, all from the same

lOcality are referred to Cantiug frugivorqgg (Figure 10).

Variations in degree of tooth wear and in size make it

 

95
improbable that any of the specimens come from the same
individual. The specimens fit closely in size and
morphology with the emended diagnosis of Beard (1988) and
the descriptions of Pelzcodus frugivorous and g. trigonadus
in Matthew (1915). The specimens are considerably smaller
than the corresponding teeth of Q. abditus and Q. ventigglia
reported by Gingerich and Haskin (1977). The /M3 is much
more slender than specimens of Q. mtkeaaai and Q. angulatgg.
Consistent with the emended diagnosis of Beard (1988), the
paraconid of /M1 is distally emplaced, and the trigonid has
rather inflated cusps. The M2/ is almost rectangular in
outline, the lingual side only slightly larger than the
labial. This is in close agreement to the diagram of the
type of Q. ftagivgraus in Matthew (1915). Measurements of
Qaatigg cf. Q. frugivorgus from the study area are presented
in Table 4a.
Genus Ngtharctua Leidy, 1870

Aga,aag Distributign: Middle to late Eocene (Brl-Br3)
of the Green River Basin, Wyoming. Other possible flgtaatttag
specimens have been collected from the Huerfano beds of
southwestern Colorado, and the Washakie Basin of southern
Wyoming.

11:2: $132123: Ems-=33 W Leidy, 1870

ggtaatttag ratinggni Gingerich, 1979
Holotype: UW 3007, left mandible with P/4 to M/3,

fragment of right mandible with P/3, and isolated lower

96

 

Figure 10. Cantius cf. Q. frugivorous. Occlusal view
of /M2 (UM 101162). Bar is one millimeter in
length.

 

Figure 11. Notharctus robinsoni. Occlusal View of /M3
(UM 98576). Bar is one millimeter in length.

97

incisors and canine, from the lower part of the Bridger
Formation (Brl), north of Opal, Wyoming.

Material: UM 95507— fragment of right dentary with /P3-
/M1, left /Ml, collected at BBO37, June 5,1990. UM 98576-
fragment of left dentary containing /M3, collected at BBO37,
June 20, 1991. UM 95634- fragment of left dentary containing
/M1—/M2, fragment of right dentary containing /P4, collected
at BBO44, June 9, 1990. UM 99917- right lower /P4,
collected at BB109, July 20, 1992.

Remarks: Notharctus robinsgni (Figure 11), known only
from the early Bridgerian (Brl), is larger than the middle

Bridgerian (Br2) N. tenebrgaus and smaller than the middle

Bridgerian (Br2) g. paggag and middle to late Bridgerian
(Br2-Br3) fl. rataatior (Gingerich, 1979). Consistent with

specimens reported by Beard (1988) and Gingerich (1979), the
entoconid notch is well-developed and the paraconids of the
molars are very large, much larger than in specimens of
ggalggaataa and.QQpa;agQ£ from the field area. Even the
smallest of the specimens is substantially larger than any
specimens of Qaatiaa from the field area or described in
Beard (1988) or Gingerich and Simons (1977). All four
specimens from the field area fit well within the size range
of ygtaatataa ratingoni reported by Gingerich (1979).
Specimens from the study area confirm the presence of
ggtaatatag in the early Bridgerian and are some of the

oldest specimens of the genus yet identified. Measurements

.
-.

>4

I ‘1.

98
of Notharctus robinsoni from the field area are presented in

Table 4a.

Tribe Copelemurini Beard, 1988
Genus Cogelemur Gingerich and Simons, 1977
Age and Distribution: Early Eocene (WaO-Wa7) of the

Rocky Mountain region of North America.

Type Species: Copelemur tutus (Cope, 1877)

 

anelemnr australotutus Beard, 1988

Hglotypa: USNM 22261- left dentary with alveoli for
P/l, fragment of P/2, and P/3-M/1, from the Wasatch
Formation on the slopes of Fossil Butte, Fossil Basin,
wyoming.

Qgpalaga; cf. Q. australotutug Beard, 1988

Matarial: UM 100895- talonid of left /M3, collected at
BB114, July 25, 1993. UM 101009- fragment of left dentary
with alveoli for /M1, and associated left /M2, collected at
BB116, July 29, 1993.

Remarks: Qopalemur australotutug was only known from
the type specimen. Beard (1988) provisionally referred USNM
411883, an isolated left M/2 to the species since it is of
the appropriate size and is intermediate in morphology
between Q, tgtga and Q. praetutgs. Similar to this tooth,
UM 101009 (Figure 12) has a tiny mesoinferiorly displaced
paraconid, and a distally placed entoconid. UM 101009 is

less worn than the specimen described by Beard, preserving

QO
4-

 

A.
E.

Figure 12. Copelemur cf. Q. australotutus. A. Occlusal
view of /M2 (UM 101009). B. Lingual view of
/M2 (UM 101009). Bars are one millimeter in

length.

100
the well developed paracristid and the labial cingulid. The
tooth is significantly larger than the type of Q. praetutus
described by Gingerich and Haskin (1977) and additional
specimens reported by Beard (1988). It is much smaller than

the neotype of Q. tutus figured in Beard (1988).

 

Measurements of Copelemur cf. Q. australotutus from the
study area are presented in Table 4a.
Genus Smilodectes Wortman, 1903
5gp app Distribution: Middle Eocene (Brl—Br3) of North
America.
Iypa Species: gmilodectes gracilis Marsh, 1871

§milodecte§ mcgrewi Gingerich, 1979

Holptype: UW 5021- left mandible with /P3 to /M3, lower
part of the Bridger Formation (Brl), near the junction of
the Big Sandy and Green Rivers, Sweetwater County, Wyoming.

Matarial: UM 95506, left dentary with /Ml-/M2, right
dentary with posterior root of /M1 and base of /M2,
collected at BBO37, June 5, 1990.

Remarks: gmilogectes mcgrewi is the earliest species
of gmilodacteg known. Although UM 95506 is close in size to
other early and middle Bridgerian notharctines, it differs
in dental morphology. The paraconids of both molars are
reduced, unlike the large cuspule found in Qaptaag and
flotharctpg. /M1 is more elongate, thinner, and less robust
than in the specimen of Qppalapp; from the field area and in

measurements in Beard (1988).

q.‘

..:s

:u

101

The primary difference between Q. mcgrewi and the
middle Bridgerian (Br2) Q. gracilis is the larger size of Q.
mcgrgwi. Gingerich (1979) noted that the observed size
range of the type sample of Q. mcgrewi is more than three
standard deviations larger than the observed range of a
sample of Q. gracilis from its type locality. UM 95506 fits
well within the expected size range of Q. mcgrewi. UM 95506
was recovered well below the type locality of Q. mpgrewi and
represents one of the oldest records of Qmilodectas yet
identified. Measurements of specimen UM 95506 are presented
in Table 4a.

Qmilodectag sp. indet.

Matarial: UM 98723— fragment of right dentary with
broken P/4, sheared off M/l and P/3, and alveoli for P/l,
P/2, and /C, intermandibular symphysis complete, collected
at BB074, June 29, 1991.

Remarks: Although the only tooth preserved with UM
98723 is damaged, enough remains of the specimen is to
confidently assign it to Qmilodactea. The alveoli between
the sheared /P3 and the alveolus for the enlarged canine
indicate that both /P1 and /P2 were single rooted, whereas
in uptpapptpg /P2 is double rooted (Gingerich, 1979;
Robinson, 1957). In addition, while the mandibular rami of
all species of upthargtua are at least partially fused,
those of Qpalpgagtag are unfused (Gingerich, 1979). The

mandibular symphysis of UM 98723 is unfused. Although UM

 

102
98723 is not identifiable to the specific level, the
presence of Q. mcgrewi at the same stratigraphic interval
(see below) makes it probable that the specimen belongs to
this taxon.
Notharctinae Indet.

Material: UM 99631, right distal tibia, collected at
B8014, June 20, 1992. UM 101025- left pisiform, collected
at BB038, August 1, 1993. UM 101093- distal phalanx,
collected at BB110, August 4, 1993.

Remarks: The postcranial anatomy of notharctines is
well-known, largely because of nearly complete specimens of
the middle Eocene genera gothargtgs and Smilodectes. The
postcranial anatomy of Notharctug and Qmilodectes do not
differ greatly (Szalay and Delson, 1979). Rose and Walker
(1984) found that the skeleton of the early Eocene Cantips
is very similar to its descendant flothargtus. Only
fragmentary postcranial remains are known of the early
Eocene genera Palxppdps and Copelapar, however, enough has
been found to suggest that they do not differ markedly from
the other notharctines (Szalay and Delson, 1979). The
skeleton of notharctine primates bears close resemblance to

extant lemuriform genera such as Lemur and Lepilappr (Szalay

 

and Delson, 1979; Rose, 1985).
UM 99631 comes from an area and stratigraphic horizon
where very few other fossils and no other notharctines have

been found. The specimen fits the size range of all of the

103

TABLE 4a

Measurements (in mm.) of Adapid Primates

Qantius frugivorous Copelemnr australotutas
UM 100021 UM 101009
M2/ AP 4.3 /M2 AP 4.6
Tr 6.7 Tra 3.6
UM 100026 Trp 3.8
M3/ AP 4.0 UM 100895
Tr 6.1 Ap -
UM 100025 Tra 4.6
/Ml AP 4.8 Trp -
Tra 3.4
Trp 3.5 Smilodectas mcgrewi
UM 101162
/M2 AP 4.8* UM 95606
Tra 3.4* /M2 AP 4.4
Trp 3.7 Tra 3.3
UM 101096 Trp 3.6
/M3 AP 5.5 /M3 AP 5.4
Tra 3.0 Tra 3.8
Trp 2.4 Trp 4.1

gotharttus rabinaoni

UM 95607 UM 95634 UM 99917
/P3 AP 4.1 - -
Tr 3.2 - —
/P4 AP — 5.1 5.2
Tr - 3.7 3.8
/M1 AP 5.5-5.9 5.6 -
Tra 3.7-3.8 3.7 —
Trp 4.2-4.3 4.1 -
/M2 AP — 5.8 -
Tra - 3.8 -
Trp - 4.2 —
UM 98576
/M3 AP 6.4
Tra 3.3
Trp 3 0

104
notharctine taxa identified from the study area.

UM 101025 comes from one of the stratigraphically
highest localities in the field area. Other faunal elements
from this horizon indicate an early Bridgerian age making it
likely that the specimen is representative of either
Qmilodactes or HQELEEEEEE-

UM 101093 comes from the lowest locality within the
study area. Although only Cantius has been identified from
this locality, both Copelemnr and Cantius have been found at
this level. The small size of the specimen suggests that it
may be referable to Cantius, but it could represent a small

individual of Copelemnr.

Infraorder Tarsiiformes Gregory, 1915
Family Omomyidae Gazin, 1958
Subfamily Omomyinae Trouesseart, 1879
Tribe Omomyini Trouesseart, 1879
Subtribe Omomyina Trousseart, 1879
Genus papaya Leidy, 1869
Iypa Qpagies: papaya cartari Leidy, 1869.
5gp aad Distribution: Early to middle Eocene (Brl—Ui2)
of wyoming and Utah.
papaya garteri Leidy, 1869
leptype: ANS 10335- ramus of right dentary with P3,
P4, and M2 from the lower Bridger Beds (BR2), near Fort

Bridger, Wyoming.

105

Material: UM 99658, fragment of right maxilla
containing complete P3/ and M2/, lingual half of P4/, and
labial half of M2/, Collected at BB070, June 23, 1992.

Remarks: Although two of the teeth in UM 99658 have
been damaged, the specimen is complete enough to assign it
to p. carteri. Consistent with the diagnosis of Szalay
(1976), the cingulum forms a continuous ridge around the
molars and is particularly heavy on the lingual side. The
hypocone of M1/ is less pronounced than in the diagram of
Szalay (1976), probably due to the high degree of wear of UM
99658. P3/ has a very tall, robust paracone consistent with
Szalay's diagnosis. Omoays aarteri is the largest species
of papaya and the only one that matches the size of UM
99658. Measurements of specimen UM 99658 are presented in
Table 4b.

Omoaya cf. p. carteri

Matarial: UM 101037- fragment of right mandible with
/M2, /M3, and posterior root of /M1.

Remarka: UM 101037 (Figure 13) is too large to be
either papaya minutus or p. lloypi. Although it is similar
in size and general morphology to p. carteri, there are
several important differences. The most visible way in
which it differs from p. cartari is in the smoother enamel
of the talonid basins of /M2 and /M3, and the much shallower
trigonid basin on /M2. UM 101037 was collected at the

contact between the Wasatch and Bridger Formations (early

 

106

 

Figure 13. Omoays cf. p. carteri. Occlusal view of right
dentary with /M2 and /M3 (UM 101038). Bar is

one millimeter in length.

 

Figure 14. Anemorhysis near a. wortmani. Occlusal
view of /M1 (UM 101159). Bar is one

millimeter in length.

 

107
Brl) and is one of the oldest identified specimen of papaya,
possibly accounting for its less complex appearance.
Measurements of Omoays carteri from the study area are
presented in Table 4b.
Tribe Washakini Szalay, 1976
Genus washakius Leidy, 1873

Typa Species: flaapataaa,iaaigaaa Leidy, 1873.

App app Distribution: Middle to late Eocene (Brl—Uil)
of North America.

WBahakiua insigais Leidy, 1873

Holptype: ANS 10332— right dentary with M2 and M3, from
the lower Bridger Formation (Bridger B), Bridger Basin,
wyoming,

Matarial: UM 98575— fragment of the right dentary
containing /P3, roots of /P4, alveoli of /C and /P2, and
mandibular symphysis, collected at BBO37, June 20, 1991.

Raaarka: Consistent with Szalay's (1976) diagnosis of
washakiaa inaiaais, /P3 of UM 98575 has a prominent
parastyle. The anterior portion of the mandible is
anteroposteriorly compressed with a vertically emplaced /C
and /P2, not elongated with an anteriorly projecting /C and
/P2 as in the omomyines. The mandibular symphysis is more
vertical than in Omoaya parteri. The two alveoli anterior
to /P3 are equal in size indicating similarly sized /C and
/P2. Measurements of specimen UM 98575 are provided in

Table 4b.

 

108
Subfamily Anaptomorphinae Cope, 1883
Tribe Trogolemurini Szalay, 1976
Genus Anemornysis Gazin, 1958

App app Distribution: Early to middle Eocene (Wa3—Br1)
of North America.

Typa Species: Anemornysis sublettensis Gazin, 1952

Anemorhysis wortmani Bown and Rose, 1984

Holotype: USGS 6554- right dentary with P/3-M/2, roots
of I/l and M/3, and alveoli of I/2 and C, from Upper
Willwood Formation (Wa6), Washakie County, Wyoming.

Anaaprnysis near a. wortmani Bown and Rose, 1984

Matarial: UM 101159- right /Ml, collected at BB110,
August 5, 1993.

Ramarks: UM 101159 (Figure 14) differs from
ABQEQELMEifi paarcei described by Gazin (1962) in being
longer and thinner. It is longer and much more slender than
A. applettanaia. Although similar in length to specimens of

a. pattaaapai and a. aprtmani described by Bown and Rose
(1987) and.Q. natronanais described by Beard et al. (1992),
it is much thinner. The specimen has a better-developed
buccal cingulum than the type of A- patteraoni figured in
Bown and Rose (1984). The hypoconulid is better—developed
and more posterior in position than in any of the described
species of Anemoruyais. The talonid is much narrower than

the trigonid and is more triangular in outline than in a”

sab1ettanais (Szalay, 1976), A. paarpei (Gazin, 1962), A.

 

109
pattersoni (Bown and Rose, 1984) or a. natronensis (Beard et
al., 1992).

Although UM 101159 is similar in most respects to Q.
aprtmani there are some critical differences and it is not
definitely assignable to this taxon. Although this specimen
may represent a new species of Anemorhysis, more material is
needed before this can be established. Measurements of
specimen UM 101159 are provided in Figure 4b.

Omomyidae indet.

Material: UM 101036- left /C, collected at BB074,
August 1, 1993. UM 101110- fragment of right mandible with
talonid of /M3, collected at BBO37, August 1, 1993.

Ramarks: The canines of omomyids tend to be slightly
reduced and have a slight cingulum. This tooth is similar
in most omomyid genera and is therefore of little use in
generic identification. While /M3 is generally a useful
tooth in omomyid identification, the trigonid of UM 101110
has been sheared off and the talonid is very worn. Despite
the fact that washakiua has been recovered from the same
locality, the specimen fits the size range of several

omomyid taxa and is not identifiable past the family level.

washakius insigais

P/3

P3/
P4/
M1/

M2/

UM 98575
AP 1.6
Tr 1.4
UM 99658
AP
Tr
AP
Tr
AP
Tr
AP
Tr

wNNNNNNN

Measurements

Omoays parteri

(in mm.)

110

TABLE 4b

of Omomyid Primates

Anemorhysis sublettensis

/M2

/M3

UM 101159

/M2 AP 1.9
Tra 1.1
Trp 1.4

UM 101037

AP 2.2

Tra 1.9

Trp 2.0

AP 2.4

Tra -l.8

Trp 1.5

111
Order CREODONTA
Family Hyaenadontidae
Genus et sp. indet.

Material: UM 98991— left astragalus, collected at
BB013W, June 28, 1991. UM 100022— left astragalus, collected
at BB110, July 27, 1992.

Remarks: UM 98991 is the astragalus of a very large
hyaenadontid. It has a narrow trochlear tibial facet with a
shallow groove, a narrow neck, and a robust, rounded
capitulum. The fibular facet is long, pronounced, and
prominent, and protrudes laterally from the body of the
astragalus. The groove beneath and behind the trochlea
containing the ventral astragalar foramen is rather narrow,
and very deep. The specimen is considerably larger and the
trochlear groove is not as deep as in Maaonya. The neck is
somewhat more slender than that in figures of Sinppa in
Matthew (1909), but is very similar in size.

UM 100022 is the astragalus of a much smaller
individual. Although part of the trochlear tibial facet is
broken off, it appears that it was narrow with a very
shallow groove. The neck is exceedingly short and the
capitulum is unpronounced. The fibular facet is prominent
but short and rectangular, and does not extend laterally
from the main body of the astragalus. The groove beneath

and behind the trochlea is shallow. There does not appear

.-

u-

'0-

Ln
I

(N

'U

(U

-.a

112
to have been a ventral astragalar foramen. The specimen is

smaller than any described by Matthew (1909).

Order CARNIVORA Vicq d'Azyr, 1792
Suborder Fissipedia von Waldheim, 1813
Family Miacidae
Genus Miacis Cope, 1872

app app Distribution: Early Eocene (Wal) through early
Oligocene (Chl) of North America. Eocene (Neustrian-
Headonian) of Europe, and upper Eocene of Asia.

Typa Species: Miacis parvivorus Cope, 1872.

Miacis latidens Matthew, 1915

leotype: AMNH 14766— right dentary with /M2-/M3, and
alveoli of /Pl-/M1, and part of left maxilla with M1/-M2/,
collected from the Lost Cabin beds of the Wind River Basin.

Material: UM 100028- right M1/, collected at BB110,
July 27, 1992.

Remarks: As is common of fossils from BB110, the
lowest locality in the section, UM 100028 (Figure 15) shows
signs of considerable abrasion and wear. The irregular
pattern of nicks and scrapes, both on the sides and on the
crown of the tooth indicate that most of this wear is due to
transport.

UM 100028 fits the size range of three early to middle
Eocene species of Miaaia described in Matthew (1909, 1915),

Gazin (1962) and Gingerich (1983), M. exigaaa, M.

113
parvivoroua, and M. latidens. The small cuspule on the
lingual cingulum found on the molars of M. parvivorpus is
absent on UM 100028. The lingual side of the tooth is wider
and blunter, and the parastyle wing is blunter and does not
extend as far posteriorly as that in M. exigaus, and.M.
parvivorous. While UM 100028 has a slightly thicker lingual
cingulum than the type specimen of M. latidena, it is

identical in all other ways. Measurements of specimen UM

100028 are provided in Table 5.

 

Figure 15. Miapia latidans. Occlusal view of M1/
(UM 100028). Bar is one millimeter in

length.

114
Genus vulpavus Marsh, 1871
5gp app Distribution: Early to middle Eocene (Wa2-Br1)
of North America.
Iypa Species: vulpayas palustris Marsh, 1871

Malpavua prpfectus Matthew, 1909

Holotype: AMNH 12626- complete skull, both lower
mandibles, complete fore and hind limbs, collected from the
middle Bridger (Br2) at Grizzly Buttes, Wyoming.

Material: UM 101100- upper left Ml/ with broken
metastyle wing, collected at BB110, August 6, 1993.

Remarks: Similar to the type specimen of MMLpayaa
EélEELELE (Matthew, 1909), the metastyle wing of UM 101100
has been broken off. The specimen is approximately thirty
percent smaller than the type of M: paluatris and twenty
percent smaller than the type of 13 bargeri figured in
Wortman (1901). In addition to being slightly larger than
specimens of 11 Qanavus figured by Guthrie (1971), the
specimen has a broader lingual cingulum on the parastyle
wing, and a more prominent paraconule. Although the type
consists of lower dentition, Gazin (1952) described.yz aaiaa
as having teeth significantly smaller than those of M:
papayaa and of the same approximate size as 13 australia.
The specimen is larger and more slender anteroposteriorly
than the type of y: ovataa described by Matthew (1909)

The specimen is only slightly smaller than the type of

Malpavua profaptua described and figured in Matthew (1909)

115
and has been referred to this species. Morphologically it
is very similar to the type. The hypocone is large and
located in a more posterior position than in other members
of the genus. It continues into cingular ridges along the
posterior side and the anterolingual portion of the tooth.
The protocone is connected to a minuscule paraconule and an
indistinct metaconule. Measurements of specimen UM 101100
are provided in Table 5.
Family Viverravidae
Genus Viverravus Marsh, 1872

Map app Distribution: Late Palaeocene (T15) through
middle Eocene (Ui2) of North America. Problematic specimens
from the upper Eocene (Headonian) of Europe, and lower
Oligocene of Asia.

Eypa Qpecias: Vivarravus gracilis Marsh, 1872

Vivarravua grapilia Marsh, 1872

leotype: Complete set of lower jaws, and a single
upper molar. Collected from the lower Bridger beds (Br2) at
Grizzly Buttes, Uinta County, Wyoming.

Material: UM 101017- left Ml/, collected at BBO37,
August 1, 1993.

Remarks: In addition to being slightly larger, the
lingual side of UM 101017 is thinner and less blunt, and the
parastyle wing is less pronounced than in specimens of
Vivarraypa minytus figured in Matthew (1909). It is less

than half the size of the type of the lower Bridger

116

Viverravus sicarius figured in Matthew (1909) and reported
by Robinson (1966). The specimen fits Robinson's (1966)
description of Viverravus gracilis in having a well
developed hypocone forming a broad cingular shelf, and in
having a heavy anterior lingual cingulum. The anterior
lingual cingulum is less developed and the hypocone is
absent in Viverravus apataa. The specimen is slightly
smaller than the closely allied'viverravus dawkinsianns.
Measurements of specimen UM 101017 are provided in Table 5.

Viverravus sp. indet.

Material: UM 100023- anterior half of left P3/,
collected at BB110, July 27, 1992.

Remarks: UM 100023 is unfortunately not complete enough
to assign specifically. The cusps are extremely high and
sharp, with a ridge running down the medial section of the
paracone towards the anterior cuspule. The anterior
accessory cuspule is better developed than in the lower
Bridgerian Viverravus sicarius. The tooth is too large to
be M. araailia or y: dawkinsianus, and too small to be M:
sicariua or M: acutus. It is most similar in size to M:
minutaa described by Matthew (1909) or y; latpaus described
by Gazin (1952) however the upper dentition of both these

species is poorly known. Measurements of specimen UM 100023

are provided in Table 5.

117
Fissipedia indet.
Material: UM 98775m, claw, collected at BB069, June 30,
1991.
Remarks: Carnivores are rare in the higher beds within
the study area. The two exceptions to this are UM 98775, a

single claw, and UM 101017, a single viverravid tooth (see

below).
TABLE 5
Measurements (in mm.) of Carnivora
_i_¢_§n a i ___latidens Vin—meme Deaf—aegis
UM 100028 UM 101100
Ml/ AP 4.8 Ml/ AP 6.2
Tr 7.9 Tr 8.1
Vivarravus sp. indet. Vivarrayaa gracilis
UM 100023 UM 101017
P3/ AP 4.8* Ml/ AP 4.8
Tr 2.2 tr 3.5

Order CONDYLARTHA Cope, 1881
Family Meniscotheriidae Cope 1882

Remarks: The Meniscotheriidae were highly specialized
condylarths with precociously advanced dentitions. The
cheek teeth are lophodont, and the molars are highly
molariform (Gazin, 1965). Although the selenodont pattern
of their cheek teeth resembles that of artiodactyls they are
not implicated in the ancestry of any modern ungulate groups

(Carroll, 1988). Found in various locations throughout the

118
North American west and in Europe, they are most abundant in
the early Eocene of the San Juan and Green River Basins and
adjacent areas.
Subfamily Meniscotheriinae Cope, 1882
Genus Meniscotherium Cope, 1874

5gp app Distribution: Late Palaeocene to Early Eocene
(Cf3-Wa7) of western North America, particularly the Rocky
Mountain interior.

Iypa Spacies: Meniscptherium chamense Cope, 1874

Remarks: The premolars of Meniscotheriaa are

relatively molariform resulting in a tooth row comparatively
homogenous in both size and shape. Both the upper and lower
cheek teeth of Maniscotherium are characterized by a more
selenodont occlusal surface than the molars of
contemporaneous condylarths. Meniscotherium is the most
distinctly herbivorous condylarth (Gazin, 1965).

Gazin (1965) was the first to study Maniappthariaa in
depth since Cope described the family in 1882. Gazin (1965)
felt that of the five described species only three were
valid. Gazin (1965) considered Meniscotherium
aaaipingalatum.undefinable since it was based on a single
deciduous lower premolar. Meniapothariaa.priscum.was
synonomyzed with M. tapiactis since the development of the
metastylid is variable, and this was the sole basis for the
species. The three accepted species are M. ahampnaa, M.

tapiactia, and M. appaataa. Although the types of the three

119
species of Maniscotherium come from widely separated areas,
they are all known from the middle to late Wasatchian of the
Green River Basin.
Meniscotherium chamense Cope, 1874

Holotypa: AMNH 4425- portions of both lower mandibles
with /P3—/M3 intact, San Jose Formation (Wa3—6) in the San
Juan Basin, New Mexico.

Material: UM 100027- right Ml/, right I3/, and right
proximal radius, collected at BB110, July 27, 1992.

Remarks: The incisor included with UM 100027 is a
typical condylarthan incisor and of little help in
identification. The proximal radius included with UM 100027
has a broken, slender shaft and a highly expanded, rather
rectangular articular surface, consistent with the
description of Gazin (1965). This is typical of all three
species of Maniapptharium and is of little help in specific
identification. The M1/ included with UM 100027 retains the
characteristic unworn, high crescentic cusps associated with
a younger individual.

The tooth is longitudinally more slender than figures
of M. appaataa.but similar to figures of M. tapiacitia and
M. Qaaaaaaa in Gazin (1962, 1965). The tooth also has an
anteroposteriorly compressed lingual portion similar to
specimens of M. paaapaaa described by Gazin (1962). The
tooth is much more slender transversely, and much less

lophodont than Ml/ of M. ropaatum.illustrated by Gazin

120

(1965) and West (1973). Consistent with the condition of
illustrated specimens of M. chamense in Gazin (1965) and by
West (1973) the protoloph and metaloph of M1/ differ only
slightly in size whereas the protoloph is a much smaller
cusp than the metaloph in M1/ of Meniscotherium robustum.
Although morphologically similar, UM 100027 is
approximately 25% larger than M. tapiactia. The specimen is
most similar in size and morphology to Meniscotharium
ppaapaaa illustrated by Gazin (1965). Measurements of
specimen UM 100027 are provided in Table 6.

Maniscotherium sp. indet.

Matarial: UM 100894- several fragmentary teeth,
collected at BB114, July 25, 1993.

Remarks: The teeth of specimen UM 100894 display the
high degree of selenodonty characteristic of Meniappthariaa,
however none of the fragments are complete enough to make a
specific assignation.

Family Hyopsodontidae Trouessart, 1879
Subfamily Hyopsodontinae Trouessart, 1879
Genus Hyppaodus Leidy, 1870

gap app Diatribution: Early to late Eocene (Cf3-Du) of
western North America.

,Iypa Qpepies: Qyppappaa paulaa Leidy, 1870.

Remarks: Although Hyopsodpa is one of the most common
mammalian genera in the Eocene deposits of Wyoming, and

while it is particularly common in the higher Bridger beds,

 

 

121
it is represented by only five specimens from within the
study area. Although four of these were collected at a
single locality, BB110, the lowest locality within the study
area, differences in size (Table 6) indicate that two
species are present. The fifth comes from considerably
higher up in the section, but still from within the Wasatch
Formation. McGrew and Sullivan (1970), working in slightly
younger units adjacent to the study area, reported only a
single specimen of Hyopsodus.

The phylogenetic relationships of Hyopapdua species
have proven difficult to define. Gazin (1968) was the first
to study Hyopspdus in depth. He found that, although known
from abundant specimens, the various species are difficult
to separate on the basis of dental morphology. There is
very little difference in tooth structure between early
specimens of Hyppspdus and later ones. Matthew (1909) noted
that while the teeth of the various Bridger species show
little advance over the Wasatch or Wind River species, there
is a trend towards more complex premolar crowns and more
crowded tooth roots. Gazin (1968) did not observe this
increasing complexity, noting only that the P2/ of the
Bridger specimens looks more like the P3/ of the Wasatchian
specimens, and the P3/ of the Bridger looks like the P4/ of
the Wasatchian. He did find that later Eocene (Uintan)
specimens trend towards more lophodont molars. This trend,

however, is not observed in early or middle Eocene

122
specimens. As a result, the various species of Wasatchian
and Bridgerian Hyopsodus are virtually indistinguishable
from each other except for size. (West, 1973, 1979, Gazin,
1968).
Hyopsodus minisculus Cope, 1874

Holotype: ANS 10259- left maxilla with M1/ to M3/,
collected from the Blacks Fork Member of the Bridger
Formation (Br2), near Fort Bridger, Wyoming.

ayppaoaus cf. Q. minisculus Cope, 1874

Material: UM 98665- fragment of left dentary containing
/M2 and the roots of /M1, collected at BB013, June 25, 1991.

Remarka: As mentioned above size is considered the
best criterion for differentiating species of Qyppappaa.

The specimen was compared to five early to middle Eocene

species of Hyppsppua in Gazin (1952; 1962; 1968), Matthew

(1909, 1915) and West (1973). Based on size the specimens
are referred to Byppsopaa minisculus. Measurements of

specimen UM 98665 are provided in Table 6.
Qyppappaa mitipalaa Cope, 1874

Holotype: USNM- left ramus of mandible with /M1 to /M3,
type missing since before 1907, "Wasatchian early Eocene,
San Jose Formation, San Juan Basin, New Mexico."

Qyppappaa cf. Q. miticulus

Matarial: UM 100020- right /P4, collected at BB110,

July 27, 1992. UM 100030- left /M1, collected at BB110, July

27, 1992.

 

 

e .

I,

" TIM

‘ m

 

 

 

 

 

123

Remarks: Two specimens fell well under the size range
of Hyppspdua‘wortmani and best fit the size range of the
Wasatchian species Q. miticulus. Measurements of specimens
UM 100020 and UM 100030 are provided in Table 6.

Hyopaodua wortmani Osborn, 1902

Holotype: AM 4716- portions of both maxillae,
premaxillae, and both rami of mandible with I2/, P3/-M3/,
and /P3-/M3 represented, collected from the late Wasatchian
of the Wind River Basin, wyoming.

Hyopsppas cf. Q.wortmani Osborn, 1902

Material: UM 101150- labial half of right M2/,
collected at BBll4 (wash), August 5, 1993. UM 101156- right
M2/, collected at BB110 (wash), August 19, 1993. UM 101157-
right /M1 collected at BB110 (wash), August 19, 1993.

Remarks: Three specimens of Qyppappaa from the lowest
two localities within the field area fell well below the
size range of Q. miniapulus and best fit the size range of
Q. apataaaa. Measurements of specimens UM 101156 and UM

101157 are provided in Table 6.

Order TAENIODONTIA Cope, 1876
Family Stylinodontidae Marsh, 1875
Ramarka: Stylinodonts were among the most highly
specialized mammals of the Early Cenozoic. Features such as

rootless, ever-growing teeth, and large well—developed claws

Mpniapptherium chamense

I3/

Ml/

/P4

Measurements

UM 100027

AP 2.7
Tr 3.9
AP 11.5
Tr 6.3
UM 100020

AP 3.9
Tr 2.5

124

TABLE 6

(in mm.) of Condylartha

UM 101156
M2/ AP 3.2
Tr 4.3
UM 101157
/Ml AP 3.1
Tra 2.0
Trp 2.3
Hyopsodus miticulus
UM 100030
/M1 AP 3.4
Tra 2.5
Trp 2.7

Hyopsodus minisculus

/M2

UM 98665
AP 3.5
Tra 2.6

Trp 2.8

Hyopsodus wortmani

 

 

 

 

 

125
suggest the animals dug their food, probably roots, from the
ground. The phylogenetic relationships of stylinodonts
remain somewhat conjectural.
Stylinodontidae, gen. et sp. indet.

Material: UM 99844m- Right terminal phalanx, probably
from the pes, tip broken off, collected at BB036, July 16,
1992.

Remarks: UM 99844m is the only record of a stylinodont
from within the study area. The specimen is a large, robust
claw 30.3mm in length, and 12.5mm in width at the proximal
end, and is similar to the description and photograph of the
undetermined stylinodont described by Gazin (1952). It
tapers towards the distal end of which approximately 5mm is
broken off. The articular surface is broad and deep, within
only a slight keel. Although Qtylinodon is the only known
genus of stylinodont known from the middle Eocene of the
Green River Basin, not enough material is present to

definitively assign the specimen past the level of family.

Order TILLODONTIA Marsh, 1875
Family Esthonychidae Cope, 1883
Subfamily Esthonychinae Zittel and Schossler, 1911
Remarks: Subfamily Esthonychinae differs from other
esthonychids by its large second lower incisor with enamel

only on the anterior, labial, and lingual sides.

126
Genus Esthonya Cope, 1874

Iypa Species: Esthonya bisulcatus Cope, 1874

gap app Distribution: Late Palaeocene (Cfl) through
early middle Eocene (Brl) of North America and Asia, and
early Eocene of Europe (Sparnacian or Cuisan).

Esthonya acatidens Cope, 1881

Holotype: AMNH 4807- left /M1 and /M2, collected from
the Lost Cabin beds (Wa7) of the Wind River Basin, Wyoming.

Material: UM 100896- bone and tooth fragments including
lower right /Il, posterior half of lower left /P4, lingual
half of lower left /M2, collected at BB115, July 25, 1993.

Remarks: UM 100896 represents an older individual of
Eathpnyg. All three teeth are worn down. Although the
specimen is similar in size to three species of Esthpnyg,
only one species, Eathonya acutidens, has been reported from
the Green River Basin. Fragments of the lower mandibles
associated with the teeth indicate that the mandibular rami
were likely fused, consistent with the diagnosis of the
Esthpnya apatularia - Q. piaulcatus — p.5cutidens lineage
given by Gingerich and Gunnell (1979). The /M2 of UM 100896
is approximately 30% larger than the type of Esthonya
apatulaaia. The /Il of UM 100896, although well worn, is
much thicker than that of Eathonya pisulcatua figured in
Gazin (1953). Although the anterior half of /P4 is missing,

the tooth is complete enough to show that it is much larger

than either Qatapaya apatularia or a. piaulpatia, and

127

slightly larger than the type of Q. acutidens. All three

teeth are similar in size to specimens of Esthonyy acutidens

measured by Stucky and Krishtalka (1983). Measurements of

specimen UM 100896 are provided in Table 7.

TABLE 7

Measurements (in mm.) of Tillodontia

Esthonya acutidens.

UM 100896
/Il AP 3.2
Tr 3.6
/P4 Ap -
Tr 6.3
/M2 AP 8.8
Tra 6.8
Trp -

Order ARTIODACTYLA Owen, 1848
Suborder Bunodonta Kowalevsky, 1873
Family Diacodexeidae (Gazin, 1955)
Subfamily Diacodexeinae Gazin, 1955
Genus Diacodexis Cope, 1882
Map app Distribution: Early to middle Eocene (Wal-Br3)
of western North America, early Eocene of Europe.
Iypa Species: Diacpdaaia secana Cope, 1881
Diacodexia secana Cope, 1881
Map app Diatribution: Early to middle Eocene (WaO-Br2)

of western North America.

 

 

 

128

Material: UM 100024— left /P4, collected at BB110,
July 27, 1992. UM 101092- left /P3, collected at BB110,
August 4, 1993.

Remarks: The premolars of lower Eocene artiodactyls
are not highly distinctive teeth. UM 100024 and UM 101092
are relatively low cusped and rather worn teeth. The
specimens agree well in both size and morphology with
specimens of Diacodexis secans described by Krishtalka and
Stucky (1985, 1986), and Robinson (1966). The paraconid of
both teeth is a small, but distinct, cuspule on the anterior
side of the protoconid. In both cases the protoconid is the
major cusp and is well separated from the hypoconid.

Both UM 100024 and UM 101092 fall well below the size
range of Baapphoaas (Stucky and Krishtalka, 1990) and well
above that of Diacodaais chacensis (Robinson, 1966; Sinclair
1914). Although both teeth are similar in size to specimens
of Antiappdpn pygaaaaa measured by West (1973, 1984) and
Robinson (1966), they differ in other aspects. Most
significantly, both specimens lack the distinct metaconid
seen in specimens of a. pygaaaaa from the Bridger Basin
(West, 1984). Measurements of specimens UM 100024 and UM
101092 are provided in Table 8.

Diacodexia sp. indet.
Matarial: UM 101099 left astragalus, collected at

BBllO, August 5, 1993.

129

Remarks: All artiodactyls recovered from the study area
have been referred to the genus Diacodexis, the most
primitive known artiodactyl. Diacodexis is considered to be
ancestral to all other artiodactyls and many of the features
that characterize modern artiodactyls are already present
(Krishtalka and Stucky, 1985; Carroll, 1988). The most
important of these features is the unique double—trochleated
arrangement of the astragalus. While the general pattern of
the astragalus of Diacodexis is reminiscent of primitive
condylarths there are some large morphological and
functional differences (Schaeffer, 1947).

The astragalus of Diapodexis is more slender and less
robust than those of contemporaneous artiodactyls of similar
size (Rose, 1982, 1985). Specimen UM 101099 was compared to
specimens and diagrams of all comparably-sized lower and
middle Eocene artiodactyls and fits the description of Rose

(1982, 1985).

TABLE 8

Measurements (in mm.) of Artiodactyla

Diapodexis aecana

UM 100024 UM 101092
/P4 AP 4.9 /P3 AP 5.3
Tr 2.5 Tr 2.8

 

 

130
Order PERISSODACTYLA Owen, 1848
Suborder Hippomorpha Wood, 1937
Superfamily Equoidea Gray, 1821
Family Equidae Gray, 1821
Genus Orohippus Marsh, 1872
App app Distribution: Middle Eocene (Brl-Br2) of

western north America, primarily the Green River Basin

Eypp Species: Orohippus pumilas Marsh, 1871
Orphippua paailus Marsh, 1871

Holotype: YPM 11336— fragment of the right maxilla with
P3/ to M2/ and roots of P1/ and P2/, from the Bridger
Formation at Marsh's Fork Wyoming (Br2).

cf. Orphippua paailua Marsh, 1871

Matprial: UM 94980- left dentary with /P3 and /M1,
roots of /P2, /M2, and /M3, collected at BB019, June 29,
1989.

Remarks: Of the five species of Orohippaa, only two, p.

paailus and p. aaipa have been found in the early Bridgerian

(Brl). UM 94980 fits well within the size range of
papaippaa paaiApa and is much smaller than p. majpr (Kitts,
1957). Although the specimen is of comparable size with

Hyaacpthariaa'vasaccianae, known from the lower units of the
study area, /P3 appears to have a minuscule entoconid, a
feature not found in anapptpaaiaa. The tooth is slightly
abraded in the area around the entoconid making this feature

difficult to discern. Kitts (1957) considered p. paaAAaa to

131
be the direct descendant of Hyracotherium vasacciense and
the progenitor of all other species of Orohippus.
Measurements of specimen UM 94980 are provided in Table 9.
Orohippus sp. indet.

Material: UM 98727— right astragalus, collected at
BB075, June 29, 1991.

Remarks: The astragali of Orohippas and all subsequent
equids are differentiated from Hyracotherium by having
trochlear crests inclined at an angle, rather than parallel
to the long axis of the foot (Kitts, 1957). In addition,
the medial trochlear crest extends to the navicular facet.
In Hyaappthprium.the neck is slightly longer and the medial
trochlear crest does not touch the navicular facet (Gunnell,
pers. comm.). The navicular facet of UM 98727 is central in
position beneath the main body of the astragalus rather than
medially emplaced as in diagrams of Eyaapptheriaa.in
Radinsky (1966a) and Kitts (1956).

Genus Hyaacpthpriaa.0wen, 1840

App app Diatributipn: Early to middle Eocene (WaO—Wa7)
of Europe and North America.

Iypp Species: Hyaacotheriaa leporinpa Owen, 1840

Rpmarka: Early Eocene equid systematics have undergone
substantial revision since the first specimen of
anapptMpaiaa.was found in 1838. Granger (1908) revised the
genus Hyaapptheriaa, recognizing eleven species. Kitts

(1956), with substantially more material, recognized three

 

132
North American species. Although he did not formally study
any European specimens, he felt that specific separation of
these from North American specimens would be difficult.
Wortman (1896) synonymized Hyaacotherium.vasaccienap,
Q.;apaa, Q. cuspidataa, Q. venticolaa and Q. anpastidpns.
Kitts (1956) revised this, separating Q. vasacciensp and Q.
papa; into one species (Q. vasacciense), and the remainder
into a second (Q. anpastidpns), largely on the basis of
stratigraphic position. The types of the Q. vaaappipnaa
group are all from the late Wasatchian of southwestern
Wyoming, those of the Q. aapastidens group are from various
early Wasatchian localities in Wyoming and adjacent states.
Rather than separate these animals into a larger number of
formal species, Kitts used the term."subspecies" to
distinguish groups of specimens with overlapping
morphological characters. This thesis follows the
classification of Kitts (1956).
Hyaapptharium.vaaappienaa (Cope, 1872)

leotypp: AMNH 4658- left M/2, from the lower Eocene
Knight Formation, near Evanston, Wyoming.

Material: UM 100890— right /M3, left /M3, right M2/,
and associated tooth fragments, collected at BB114, July 25,
1993. UM 101158- upper Mx/, collected at BB110 (wash),
August 5, 1993.

Remarks: All of the teeth that comprise specimen UM

100890, with the exception the left /M3, are damaged to some

 

133
extent. The diagnosis of the specimen therefore is based
primarily on this tooth. The heel is slender and elongate,
unlike the short structure found in Drohippus. The tooth is
broader than in Q. anpastidens and its synonyms reported by
Kitts (1956). Hyracotherium vasacciense is most easily
differentiated from.Q. craspedotum by its much smaller size.
The specimen is substantially smaller than specimens of Q.
craspedotaa.reported by Kitts (1956) and Guthrie (1971), and
figured by Gazin (1962). Contrary to Kitts (1956), Guthrie

(1971) recognized Q. index as a valid species, independent

 

from.Q. vasacpipnae. Specimen UM 100890 is substantially
larger than the single specimen of Q. iappa reported by
Guthrie (1971). Specimen UM 100890 is closest in size to
specimens of Hyaacotherium.y. vasappiense from the La Barge
sample described by Kitts (1956). Measurements of specimen
UM 100890 are provided in Table 9.
Equidae, gen. et sp. indet.

Material: UM 98666- fragment of right Mx/, possibly
M2, collected at BB013, June 25, 1991. UM 98656-
postcranial material including a left distal femur, left and
right distal tibiae, a right humeral head, seven caudal
vertebrae, three distal metacarpals, and a left calcaneum,
collected at BB013, June 25, 1991.

Remarks: Two closely related genera of equids are

known from the early and middle Eocene of Wyoming. Kitts

(1956, 1957) studied both Orphippaa and Hypnpptharium in

134
depth and observed that, in many respects, the postcranial
anatomy of the two genera is similar. Certain bones,
particularly those of the pes, have proven useful for
identification (see above). With additional study it may
become apparent that it is easier to separate early
specimens of Orohippus from late specimens of Hyaacptheriaa
using the shape and orientation of certain of the hind limb
elements than with the dentition. The most commonly used
criterion in separating the two is morphology of the teeth.
Orohippas is considered to be the Bridgerian successor to
Hyaacpthpriaa (Kitts, 1956; 1957) As the two genera are
considered to be members of an evolutionary continuum, the
critical dental characteristics may vary considerably.

UM 98666 is a portion of an upper right cheek tooth,
probably an M2/. The criteria used by Kitts (1956, 1957) to
differentiate the two genera are absent on this specimen.
UM 98656 fits the size range of both early Eocene equids,
Hyaacothpriaa and prohippus, and likely belongs to one of
these two genera. The distal tibiae fit perfectly with both
Hyraaotheriaa and Orohippus astragali in the University of
Michigan collection. Although the specimen falls within the
size range of QaApaaAptpa there are several morphological
differences. The astragalar groove of the tibia is deeper
than that of a distal tibia found associated with

Qalanplptea material from the same locality. In addition the

 

 

135

bone is more rounded in cross section than the homologous

 

bone in Selenaletps.

Superfamily Brontotherioidea Hay, 1902
Family Brontotheriidae Marsh, 1873
Subfamily Lambdotheriinae Osborn
Genus Lambdothprium Cope, 1889

App app distribution: Early Eocene (Wa4-Wa7) of North
America.

,gypp Specips: Lambdotherium.popoapacium (Cope, 1880)

Lambdotherium.popoapacium (Cope, 1880)

Holotype: Right P/4-M/3, from the Lostcabinian of the
Wind River Basin, wyoming.

Material: UM 100891— associated teeth including left
/P2, left /P4, right /M1, left P4/, and left M1/, collected
at BB114, July 25, 1993.

Remarka: Bonillas (1936) synonymized all other
described species with Lambdotherium.popoapacium. Prior to
this the main criterion for specific separation was the
degree of molarization of the premolars. All described
species occurred within a narrow stratigraphic interval and
most graded one into another without any clear divisions.
Previous to this revision, a complete dentition belonging to
a single individual had never been described, and it became
clear that the upper and lower dentition of the specimen
Bonillas studied (CIT 1743) had characters of several

different species.

 

136

UM 100891 (Figure 16) is similar in all aspects to the
specimen described by Bonillas (1936) and specimens figured
by Osborn (1929). The /P2 is a rather simple tooth, and is
very worn making the cusp pattern difficult to discern. The
/P4 is a high-cusped tooth and is almost completely
molariform. While a true entoconid is absent, the posterior
cingulum is thick and pronounced. Osborn (1929) using
progressive molarization of the lower premolars, considered
Laappotherium.popoapacium to be the intermediate species in
an evolutionary continuum. Based on the lower premolars, UM
100891 fits the description of Lambdotherium popapacium of
both Osborn (1929), and Bonillas (1936). Although the
ectoloph has been damaged, M1/ is easily identified as a
molar of Laappotherium.popoapacium. A thin low cingulum
encircles the crown. The four main cusps are approximately
equal in height. The protoconule, although smaller than the
other cusps, is rather large, and consistent with Bonillas'
description, is crescentic, its base curling slightly around
the base of the enlarged paracone. Measurements of specimen
UM 100891 are provided in Table 9.

Subfamily Palaeosyopinae Steinman and Doderlein, 1890
Genus Palaeosyoas Leidy, 1870
App app Distribution: Middle Eocene (Brl—Br3) of North

America. Early Eocene of Asia.

Figure 16.

 

Lambdotherium popoagacium. A. Occlusal
view of /P4 (UM 100891). B. Labial view

of /P4 (UM 100891). Bar is one millimeter
in length.

138
,gypp Species: Palaeosyops paludosus Leidy, 1870.
Palaeosyops fontinalis Leidy, 1870

Holotype: AMNH 5107- fragmentary skull including the
left nasal, both squamosals, both parietals and right
maxilla containing dP4/, M1/ and M/2, collected from the
lower Bridger formation (Brl), near the confluence of the
Big Sandy and Green Rivers, central Green River basin,
Wyoming.

Palaeosyops cf. g. fontinalis Leidy, 1870

Matprial: UM 98732— trigonid of left /dP4, collected at
BB012, June 29, 1991. UM 99815- fragments of Mx/, collected
at BBO96, July 15, 1992.

Remarks: Palaeosypps fontinalia and Eotitanpps
poraalis are the only two large brontotheres known from the
Early and Middle Eocene of the Green River Basin.
QaAaapayppa is likely derived from Eotitanops (West, 1973).
Gazin (1952) considered Palaeosyops and Eptitanppa
congeneric. Although their teeth are morphologically
similar, West (1973) and Robinson (1966) consider them two
distinct genera, based primarily on their substantial
difference in size.

Based on size, UM 98732 is referred to gaAappayppa
QpatiaaAia rather than the smaller EQELEQQQEE bpraalia.

Gazin (1952) noted that the deciduous teeth of

paappatpaaiaa, a taxon closely related to Palaepsyppa, are

identical except for size to their permanent counterparts.

139

The trigonid of UM 98732, a deciduous premolar is preserved
in its entirety, and is slightly larger than any permanent
/P4 of Q. fpntiaalia measured by Robinson (1966), and is far
larger than /P4 of Eotitanops borealis. Although the
specimen is fragmentary, the size of UM 98732 is also
indicative of Palaeoayops cf. 2. fontiaalia. Measurements
of QaAappayppa cf. a. fontinalis from the study area are
provided in Table 9.

Suborder Ceratomorpha Wood, 1937

Superfamily Tapiroidea Gill, 1872

Family Helaletidae Osborn, 1892

Genus QpAaaaAataa Radinsky, 1966

App app Distribution: Middle Eocene (Gardnerbuttean,

early Brl) of wyoming. Few specimens of QplaaaAatpa have
been described. To date, all described specimens have been
lower cheek teeth. Locality and stratigraphy data is poor
for the holotype and the hypodigm described by Radinsky
(1966b). The holotype and two other specimens were found in
a drawer of Bighorn Basin specimens in a box containing
Qpptpppa palpipaAaa, a species known only from the Lysitean
and Lostcabinian (Wa6-7) (Radinsky, 1966b). Guthrie (1971)
reported QpAaaaAptpa from the Lost Cabin Member of the Wind
River Formation but did not indicate which horizon his
specimens came from. Stucky (1984a) restricted QalpaaAataa
apppapaa to the gaAappayppa ppraalis zone (Gardnerbuttean,

early Brl) within the Wind River Basin. Specimens of

140
Qplenalptps from the study area are the first specimens
reported from outside of the Wind River Basin.

gypp Qpecies: Selenaletes scppaeus Radinsky, 1966.

Selenaletes sp. indet.

Material: UM 94877- edentulous left mandible,
collected at BB013, June 25, 1989. UM 94913— left dentary
with /M2 and /M3, fragments of right dentary containing
roots of /P2 through /M3, right distal tibia, collected at
BB013, June 25, 1989. UM 95597— right dentary with /M2,
collected at BB013, June 4, 1990. UM 98661- left M3/,
collected at BB013, June 25, 1991.

Remarks: Selanaletes scopaeua, the only described
species of Qelpna1etpa, is one of the smallest known
helaletid ceratomorphs. Morphologically it is very similar
to many other helaletids known from the late Wasatchian and
early Bridgerian of the Bridger Basin. Aside from minor
differences in individual tooth shape, the most important
distinguishing characteristic between the forms is size.
Teeth of Selenaletea are approximately 30% smaller than
those of prtodpn palcicalaa, the smallest species of
prtopon, and 20% smaller than Dilophoppn Apptaa_a, the
smallest species of Dilpphpppn (Radinsky, 1963, 1966b).

Emry (1989, 1990) recently described a tiny helaletid
ceratomorph from the Bridgerian of the Elderberry Canyon
Local Fauna in Nevada. Teeth of this animal, Ppuphia

pAypaaaa, are approximately 10% smaller than those of

|In

I...

141
Selenaletas scopaeus. Fouchia elyensis is the smallest
known ceratomorph. The teeth of Selenaletes have slightly
higher crowns, and more advanced bilophodonty than those of
Fpachia (Emry, 1990). In Selenaletes the anteroposterior
length of /M3 is less than that of /M2 yielding a /M2:/M3
ratio of 1.0 (Radinsky, 1966b). In Fouchia the length of
/M3 is longer than that of /M2 yielding a /M2:/M3 ratio of
0.85 (Emry, 1990). The Bridger specimens, and in particular
UM 94913 (Figure 17) follow the trend in Fouphia rather than
that in Qaleaaletes with a /M2:/M3 ratio of 0.80 in specimen
UM 94913 and 0.89 in UM 95597 (/M3 alveolar length). These
specimens may well occupy an intermediate position between
Fpuchia and Qelenalptes since the relative smaller size of
/M3 is considered a diagnostic character in Qelenalatea
apppapaa (Radinsky, 1966b). The specimens from the study
area are likely representative of a new species of this
poorly known genus. Measurements of specimens of
QpAaaaAptpa from the study area are presented in Table 9.
Subfamily Hyrachyinae Osborn, 1892

Remarks: This study follows the classification of
Radinsky (1967). Radinsky removed the family Hyrachyidae
from Superfamily Rhinocerotoidea, and placed it as a
subfamily in Superfamily Tapiroidea, Family Helaletidae.

Genus anachyas Leidy, 1871
App app Diatribution: Middle Eocene (Brl—Ui2) of North

America and Europe.

142

 

 

 

 

Figure 17.

 

 

 

Qalenplatas sp. indet. A. Occlusal View
of left dentary with /M2 and /M3 (UM 94913).
B. Labial view of left dentary with /M2 and
M/3 (UM 94913). bar is one millimeter in
length.

143

Iypp Species: Hyrachyas modestus Leidy, 1871.

Remarks: Myaapayaa is one of the most common mammalian
genera in the middle Eocene of western North America.
Radinsky (1967) was the first to study the hyrachyids in
depth since Wood's monograph in 1934, where 12 species in
four genera of hyrachyids were recognized. Seven of these
species (four from the Bridger Formation) were placed in the
genus Hyaachyas. Wood (1934) separated these into three
lineages or evolutionary grades, primarily on the basis of
size. Radinsky (1967), utilizing a much larger sample
reduced the number of genera to one and the number of
species to two.

Radinsky (1967) concurred with Wood (1934) that size is
the only useful criterion for separating Bridgerian species
of anappypa. Measurements of specimens of anapayaa from
the study area are presented in Table 9.

minis. 101133133 (Leidy, 1871)

Holotype: USNM 661- isolated dP3/ or dP4/ from the
lower Bridger Formation (Br2) of the Bridger Basin of
wyoming. There is some dispute about the type specimen
since Leidy (1871) originally designated this specimen as
the type of Lpphiodpn modestaa and described the genus
anapaypa the same year, based on another specimen. Wood
(1934) and Radinsky (1967) concur that USNM 661 is the

proper type specimen.

144

Material: UM 95635- cheek tooth fragments, collected
at BB044, June 9, 1990. UM 98734- fragments of right
maxilla containing P2/-P3/, M2/, fragments of M3/, and the
roots of Il/ to I3/, collected at BB077, June 29, 1991. UM
101023- associated postcranial elements including left
astragalus, left calcaneum, and left patella, collected at
BBO37, August 1, 1993. UM 101035— associated postcranial
elements including left navicular, left ectocuneiform, and
the distal end of the left second metatarsal, collected at
BB074, August 1, 1993. UM 101075— fragmentary left dentary
including part of the descending ramus, and /M3, isolated
/P3, left astragalus, collected at BB117, August 3, 1993.

Remarks: UM 95635 is assigned to Hyaachyps on the
basis of the large folded lophs of enamel characteristic of
the species. The only other animal of the similar size is
the brontothere Palaeosyops. The enamel folds of UM 95635
are considerably higher, sharper and tighter than are those
of Palaapayops.

As mentioned above, size is considered the only valid
criterion for separating species of Hyaachyas. Consistent
with Wood's (1934) diagnosis of Hyaaphyps, the protoloph of
P2/ and P3/ of UM 98734 is considerably more robust and
prominent than is the metaloph. The ectoloph and metaloph
are connected by a ridge that is only slightly lower than
the cusps themselves, whereas the protoloph is separated

from the metaloph and the ectoloph by a deep depression.

145
Although UM 98734 is larger than most specimens of Q.
modestus described by Radinsky (1967). Radinsky did report

three exceptionally large B. modestus specimens from lower

Bridger beds, and West (1973) reported a comparably large
specimen of Q. modestus from the New Fork Tongue of the
Wasatch Formation. Radinsky felt that size difference does
not warrant the recognition of two species of early
Bridgerian Hyaachyas. As more specimens of Hyrachyas are
discovered from late Wasatchian and early Bridgerian
deposits it may become apparent a second species is present.

Specimen UM 101075 is a very large specimen of
anapayaa mopestus, It is larger than any specimens reported
by Robinson (1966) from the upper Huerfano Formation (Brl),
by Radinsky (1967) from the Bridger B through D beds (Br2-
Br3), or the single specimen from the Lost Cabin Member
reported by Guthrie (1971). Measurements of specimens UM
98734 and UM 101075 are reported in Table 9.

Fam., gen. et sp. indet.

Material: UM 98578- postcranial material including
left humeral head, left femoral head, terminal phalanx,
distal metacarpal, proximal metatarsal, distal fibula, left
proximal radius, left lateral cuneiform and five vertebral
fragments, collected at BB044, June 20, 1991. UM 99661mr

two terminal phalanx, one distal metacarpal, one proximal

metacarpal, collected at BB103, June 23, 1992. UM 101101m-

146
trochlea of right astragalus, collected at BB110, July 27,
1992.

Remarks: UM 98578 is the remains of a very small
perissodactyl. The terminal phalange is only 8mm long. The
specimen may be either a small equid species, or possibly
represents some of the first postcranial remains known from
the diminutive hyrachyid Seleneletes. UM 99661m is too

large to belong to any of the early or middle Eocene equid

taxa and too small to belong to Palaeoayppa fpntiaalia. It
is unlikely representative of Lambdothpriaa, an important

Lostcabinian (Wa7) taxon, since a specimen of the Bridgerian

taxa anappyaa was identified from a lower level. It is most
likely representative of either anapayaa, or gaiaapayppa

ppaaaAAa. UM 101101m likely belongs to either a large
specimen of Hyaapptharium or a small specimen of
Lambdotheriumw It is too incomplete for further
identification.
Order RODENTIA Vicq d'Azyr, 1792
Suborder Protrogomorpha Zittel, 1893
Superfamily Ischromyoidea Wood, 1937
Family Sciuravidae Miller and Gidley, 1918
Genus Qaiaaayaa Marsh, 1871
App app Distribution: Early Eocene (Wa4) to late Eocene

(Uil) of North America.

Iypp Spepies: Qataaayaa aitidaa Marsh, 1871.

147
TABLE 9

Measurements (in mm.) of Perrisodactyla

cf. Orohippus pumilus Hyaacotheriua sp. indet.
UM 94890 UM 101158
/P3 AP 6.5 M2/ AP 7.2*
Tr 4.1 Tr 8.9*
/M1 AP 7.1 Hyaacotherium vasacciense
Tra 4.9 UM 100890
Trp 5.1 M2/ AP 6.9
Tr 8.8*
/M3 AP 9.7-10.4
Tra 5.8- 6.1
Trp 5.2- 5.8
Lambdotherium popapacium. Palaeosyops
Um 100891 cf. 3. fontinalia
/P2 AP 7.7 UM 98732
Tr 4.9 /dP4 AP 22.6*
/P4 AP 9.7 Tr 15.1
Tr 6.6
P4/ AP 9.0
Tr -
Ml/ AP 12.7
Tr 15.0
Qeleneletes sp. nov.
UM 94913 UM 95597
/M2 AP 7.2 /M2 AP 8.1
Tra 5.6 Tra 5.5
Trp 5.9 Trp 5.7
/M3 AP 8.9 UM 98661
Tra 5.8 M3/ AP 3-5
Trp 5.7 Tr 9-1
UM 101029
/P3 AP 4.7
Tr 3.9
/P4 AP -
Tr 4.4
Hyaachyas modestus
UM 98734 UM 101075
P2/ AP 10.7 P/3 AP 14.0
Tr 13.7 Tr. 8.8
P3/ AP 13.7 M/3 AP 23.8
Tr 16.5 Tra 15.9
M2/ AP 18.4 Trp 14.1
Tr 20.6
M3/ AP 19.0*
Tr 23.0*

148
Qpiaaayaa,aitipaa Marsh, 1871

Holotype: YPM 13333- fragment of left maxillary with
M1/-M3/, collected from the lower Bridger Formation (Br2) at
Grizzly Buttes, wyoming.

Material: UM 98659, Fragment of left maxilla
containing chipped /P4 and complete /M1, collected at BB013,
June 25, 1991. UM 98662, Fragment of left maxilla
containing /P3 through /M1, collected at BB013, June 25,
1991. UM 99637- fragment of right dentary containing /M1
through /M3, collected at BBO74, June 18, 1992. UM 99918-
right Mx/ and associated postcrania, collected at BB109,
July 20, 1992. UM 101018— left M2/, collected at BBO37,
August 1, 1993. UM 101031- fragment of left maxilla with
P4/ and Ml/, collected at BB013, August 1, 1993. UM 101033-
left /Ml, collected at BB013, August 1, 1993.

Remarks: The specimens agree quite closely with the
illustrations and descriptions of Qciuravua nitipaa given by
Wilson (1938) and West (1973). The anterior cingula are
well-defined and rather cuspate, a tiny cusp, the metastylid
is present near the base of the internal surface of the
metaconid. The entoconid of /P4 is less pronounced than the
other cusps on the tooth. The posterior cingulum of /M3 is
heavier than in the other molars. Tooth measurements of all
Qataaayaa teeth recovered from the study area are presented
in Table 10. The specimens are all well within the size

ranges for Qciaravus nitidua reported by West (1973). Korth

149
(1984) feels that West may have included specimens of the
smaller Q. wilsoni in his sample since West included
specimens collected from the Cathedral Bluffs Tongue of the
Wasatch formation. All three specimens exceed the sizes for
Q. wilapni reported by Gazin (1962).
Genus Knightoays Gazin, 1961

.Iypp Species: Knightomys sanior (Gazin, 1952)

App app Distribution: Early to middle Eocene (Wal-Brl)
of Wyoming, Colorado, and New Mexico.

Knightpays depreasus (Loomis, 1907)

Holptype: ACM 432- partial skull with right M1/ to M3/
from the Lysite Member (Wa6) of the Wind River Formation,
wyoming.

Material: UM 101095- right M2/, collected at BB110,
August 4, 1993. UM 101098— right /M3, collected at BB110,
August 4, 1993. UM 101163- left /M3, collected at BB110,

August 20, 1993.

Rpmarka: Loomis (1907), using several isolated teeth,
originally included the species in the genus Qpiaaayaa. Wood

(1965) recognized that the skull of the animal was identical

to that of the closely related genus Mappatpaya described by
Gazin (1961). Although both genera are found within the

study area, their ranges are distinct.
Three isolated teeth, one M2/ and two /M3s have been
referred to Knightoaya daprasaua. Although all three were

collected from the same locality, the variance in tooth wear

.
or“
.Oli‘

-
.on

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150

makes it likely that they are from three different
individuals. The metaconid of /M3 is the largest cusp, the
other cusps are all relatively the same height, the anterior
cingulum is separated from the protoconid and the metaconid.
Consistent with the description of Korth (1984) the
posterolingual lophid of the mesoconid of /M3 is elongate,
and extends back to the posterolophid. A prominent
metalophid extends labially from the protoconid, almost to
the base of the metaconid. The hypolophid is a slight,
barely perceptible ridge on the base of the talonid basin.

The M1/ is essentially square in outline. Consistent
with diagrams in Korth (1984), a prominent anterior cingulum
runs in an arc from the paracone to the protocone. The
protocone is the largest cusp. The other cusps are equal in
size, and approximately half as large as the protocone. The
mesocone is an independent cuspule rising from the posterior
flank of the metacone. The metaconule extends anteriorly
from the hypocone towards the centre of the tooth before
cutting sharply back to the base of the paracone. The
posterior cingulum is reduced in size and is almost worn
away. Measurements of specimens UM 101095, UM 101098 and UM

101163 are presented in Figure 10.

 

151
Family Ischyromyidae Alston, 1876
Subfamily Paramyinae Simpson, 1945
Tribe Paramyini Korth, 1984
Genus Paraays Leidy, 1871
App app Distribution: Late Palaeocene (Ti6) to Late
Eocene of North America, early Eocene (Neustrian) of Belgium

and France.

Eype Species: Paraaya delicatas Leidy, 1871
Paraaya excavatus Loomis, 1907

Holotype: ACM 327- fragment of right dentary with /P4-
/M3, collected from the Lysite beds (Wa6)-of the Wind River
Formation, near Bridger Creek, Wyoming.

Paraaya cf. 2. pacavatus Loomis, 1907

Material: UM 100889- right /Ml, collected at BB114,
July 25, 1993.

Rpaarka: The metaconid is the largest cusp on the
tooth, towering over a tiny trigonid basin and a deep, broad
talonid basin. The other cusps are much lower, the
entoconid barely higher than the posterior cingulum. A tiny
cuspule, the mesoconid, rises from the labial side of the
talonid basin. The enamel of the talonid basin is slightly
crenulated.

Wood (1962) split Paraays pMQavatus into four
subspecies. Korth (1984) revised this diagnosis restricting

the species to g, p. expavatas of Wood (1962). Two of the

other subspecies, 2. p taaaaa and a. p. pplipaipena were

9.

152
incorporated into a new species, Paramys taurus. The fourth
subspecies Paraays p. pardneri was incorporated into
Thiabpaya pprpitas Wood, 1962.

UM 100889 agrees well with the type description of
Loomis (1907) and the emended diagnosis of Wood (1962) of
Paraays excavatus. Although the specimen is closer in size
to Paraaya pacavatua pardneri than any of the other
subspecies of a. aapavatus described by Wood (1962),
morphologically it is closer to a. p, excavatus. The slight
crenulations on the surface of the tooth are not considered
important enough to warrant inclusion in Thisppaya plipatua.
Measurements of this specimen are presented in Table 10.

Genus Leptotoapa Matthew, 1910

App app Distribution: Early middle Eocene (Brl) to
early Oligocene (Chl) of western North America.

Iypp Qpecies: Laptotomua leptodus Cope, 1873

Remarks: ppptptpaaa and Paraays are very closely
related forms with many characters in common. Matthew
(1910) originally established Leptotpmua as a subgenus of
gaaaaya. Subsequent workers however have largely ignored
this classification. Burke (1934) using specimens obtained
from the Duchesne River in Utah, and Wilson (1940) using
specimens from the Eocene of California, were the first to
accept Laptptomus as a valid genus. Despite the striking

similarities between ppptptpapa and Paraays, paptptpapa is

the most easily differentiated of the paramyid rodents. The

 

153
lower incisors are oval in cross-section, the apex pointing
anteriorly. The enamel, therefore, is on the narrowest side
of the tooth, extending onto the lateral Surface, almost to
the posterior side. This is the reverse of the situation in
Paraaya and the other paramyid rodents, where the enamelled
anterior side of the incisor is considerably wider than the
posterior side. The cheek teeth of ppptptpaaa are rounder,
simpler and have fewer irregularities than those of the
other paramyid rodents. The crenulations characteristic of
molars of Paraaya are absent in Leptotpmus and a ridge,
absent in other paramyids, runs from the entoconid across
the talonid basin.
Leptotpmus parvus Wood, 1959

Matptial: UM 98710- fragment of the right dentary
containing /M2 and /M3, incisor groove present, collected at
BB073, June 28, 1990. UM 101030- fragment of left dentary
extending from midway through /M1 to the middle of the ramus
including the massentaric fossa, contains /M2-/M3 and the
posterior half of /M1, collected at BBOl3, August 1, 1993.

Remarks: UM 101030 agrees quite closely in size and
morphology with the type of Leptptomus parvua described in
Wood (1959) and additional specimens reported by Wood
(1962). Laptotomus parvus is one of the smaller species of
Leptotpmua, being only slightly larger than the diminutive
Q. apairpidas and p. huerfanansia. UM 98710 is closest in

size to this Leptotpmua parvua than any of the other species

 

154
of Leptotomus measured by Wood (1966). Measurements of
specimens UM 98710 and UM 101030 are presented in Table 10.
Leptotomus sp. indet.

Material: UM 99660- fragment of left maxilla with /P3
and most of /P4, collected at BB103, June 23, 1992.

Remarks: Wood (1962) proposed three informal species
groups within Leptotomus. The specimens collected from the
study area fall into the smallest species group, consisting
of ppptptpaaa huarfanensis, p. parvus, p. bridppransia, Q.
aytpnenais, and A, Maya. Wood (1962) felt that with the
possible exception of p. huerfanensis this sequence
represented a continuous evolutionary series. Based on
geography and chronology it is likely that UM 99660 is
either Leptotpmua huprfanensis or p. parvuaI however the
specimen is not complete enough to identify to the species
level. Measurements of specimen UM 99660 are presented in
Table 10.

Fam. gen. et sp. indet.

Material: UM 98577m- isolated incisor, collected at
BB037, June 20, 1991. UM 98726- two isolated incisors,
collected at BB074, June 29, 1991. UM 101031- two isolated
incisors, collected at BB110, July 27, 1992. UM 101101—
isolated incisor, collected at BB110, August 5, 1993. UM
101015- isolated incisor, collected at BB116, July 31, 1993.

UM 101164— /Mx, collected at BB110, August 5, 1993.

155

Table 10

Measurements (in mm.) of Rodentia

Sciuravus nitidus

UM 98662 UM 98659
P3/ AP 0.9 /P4 AP 1.8
Tr 1.1 Tr 2.0
P4/ AP 1.5 /Ml AP 2.0
Tr 2.1 Tr 2.1
Ml/ AP 1.7 UM 99637
Tr 2.2 /M1 AP 2.1
UM 99918 Tr 2.0
M2/ AP 2.1 /M2 AP 2.2
Tr 2.3 Tr 2.2
UM 101018 /M3 AP 2.7
M2/ AP 2.1 Tr 2.2
Tr 2.3 UM 101031
UM 101033 P4/ AP 1.7
/M1 AP 2.0 Tr 2.0
Tr 2.3 Ml/ AP 2.1
Tr 2.3
Maipatpaya papressus Leptotomus sp. indet.
UM 101095 UM 99660
M2/ AP 2.0 P3/ AP 2.2
Tr 2.1 Tr 2.1
UM 101098 P4/ AP 3.7
/M3 AP 2.2 Tr 3.9
Tr 1.8
UM 101163 A. cf. p. huerfaapnaia
/M3 AP 2.5
Tr 1.9 UM 98710
/M2 AP 3.5
gaaaaya cf. 2. aacavatus Tr 3.3
/M3 AP 4.1
UM 100889 Tr 3.3
/M1 Ap 3.2
Tra 2.7 Q. Papyas
Trp 3.1
UM 101030
/Ml AP 3.9*
Tr 3.6
/M2 AP 3.8
Tr 3.6
/M3 AP 4.6
Tr 3.6

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156
Order Incertae Sedis
Suborder Palaeanodonta Matthew, 1918
Remarks: Palaeanodonts are an early Tertiary group of
"edentates" of uncertain origin and affinity. Matthew
(1918) contended that the Suborder Palaeanodonta was
ancestral to living xenarthrans. Simpson (1931) also argued
for a close relationship with both the Xenarthra and the
Pholidota, but recognized that they are too highly
specialized to be directly ancestral. Additional evidence
is needed before the precise relationships of the various
edentate groups is sorted out.
Family Metacheiromyidae Wortman, 1903
Genus Metacheiroays Wortman, 1903
App app Distripation: Middle Eocene (Brl-3) of North
America, particularly the Bridger Basin of Wyoming.
,Eypp Qppcips: Metachairoaya marshi Wortman, 1903

Matapheiroaya sp. indet.
Material: UM 98573- third metacarpal, collected at

BBO37, June 20, 1991. UM 101037- ramus and caudal portion
of mandibular body of left dentary, collected at BB074,
August 1, 1993.

Remarks: As is typical of the posterior portion of
jaws of Matapppiapaya, specimen UM 101037 does not contain
any teeth or alveoli. UM 98573 is typical of the
metacarpals of metacheiromyids. Metacarpal III is stouter

and longer than the other metacarpals. It is not notched

.oev

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157
ventrally like the other metacarpals. Based on size, both
specimens are most likely referable to Metacheiromys
Qaaypaa, however not enough material is present for a
definitive identification.
Genus Palaeanopon Matthew, 1918

App app Distribution: Late Palaeocene (Cf2) to early
Eocene (Wa7) of North America and Asia.

Type Species: Palaaanoppn ipaavus Matthew, 1918.

Palaeanoppn sp. indet.

Material: UM 100019- left third metacarpal, collected
at BB110, July 27, 1992. UM 101094— left third metacarpal,
collected at BB110, August 4, 1993.

Rpmarks: The genus Palaeanodon is represented in the
study area by two left third metacarpals. Based on size
alone, the specimens are most likely referable to
gaAaaaapppa Apaayaa, however, the material is insufficient
for a specific identification.

Family Epoicotheriidae Simpson, 1927

Rpmarka: Like palaeanodonts, epoicotheres are uniquely
adapted to a digging lifestyle. Specializations of the
skull and skeleton indicate they were probably subterranean
burrowers (Rose and Emry, 1983).

Genus QataapaaaaAaa Simpson, 1959
App app Diatripution: Middle Eocene (Brl-Br3) of North

America.

Logs §p___secie : 1355M: when; simpson. 1959

158
Tetrapassalus sp.

Material: UM 99920- right partial humerus and ulna,
collected at BB109, July 21, 1992.

Remarks: The humerus of palaeanodonts is one of the
most important diagnostic elements. The humerus of UM 99920
is shorter and squatter than the humerus of metacheiromyid
palaeanodonts. The specimen is smaller than most other

epoicotheres, and best fits the size range of Tetrapaasalua.

159
EOCENE BIOSTRATIGRAPHY

Wood pt _A. (1941) proposed a standardized set of
Provincial Land Mammal Ages to subdivide the Cenozoic of
North America using characteristic groups of fossil mammals.
Eighteen ages defined by characteristic suites of mammals
were established, spanning the length of the Cenozoic.
These units have served as standards in the attempt to
correlate various faunas of similar age scattered across
North America. Unfortunately the provincial ages of Wood et
al. (1941) were named after lithostratigraphic units. As
the faunas of the various ages have become better known, it
has become apparent that the land mammal ages are rarely
precisely contemporaneous with the lithostratigraphic unit
for which the ages were named.

Presently the Eocene Epoch consists of four ages and
part of a fifth as defined by Gunnell et al. (1993):
Wasatchian, Bridgerian, Uintan, Duchesnean and the early
Chadronian. The present paper deals with the strata and
faunas spanning the Wasatchian-Bridgerian boundary of
southwestern Wyoming, and details two boundaries; the
biochronologic Wasatchian—Bridgerian (=Lostcabinian-
Gardnerbuttean) boundary, and the lithostratigraphic
Wasatch-Green River-Bridger formational bOundary. As is

shown in Figure 12, the two are not correlative within the

study area.

F

I;

160

The Wasatchian and Bridgerian Land Mammal Ages have
been further subdivided into a series of zones ("subages").
Table 11 presents the Eocene biostratigraphic terminology
used in this thesis. As more and larger Palaeogene fossil
mammal assemblages are discovered, the relationships between
the various subages in the Tertiary Basins of the Rocky
Mountain area shall become better understood. In recent
years Eocene faunas have become better known and
correspondingly the Land—Mammal Age system particularly the
Bridgerian has undergone substantial revision.

WASATCHIAN LAND MAMMAL AGE

Hayden (1869) first used the name Wasatch as an
informal reference to a series of formations in northeastern
Utah and southwestern wyoming. Granger (1914) subdivided
the Wasatchian of the Big Horn Basin into four units: Sand
Couleean, Graybullian, Lysitean, and Lostcabinian. This
paper utilizes the terminology of Gingerich (1989), who
redivided the Wasatchian into eight biostratigraphic zones
(WaO-Wa7). These zones correspond for the most part to
Granger's units. This study is concerned primarily with
Lysitean (Wa6) and the Lostcabinian (Wa7).

BRIDGERIAN LAND MAMMAL AGE

Matthew (1909) subdivided the Bridger Formation into
five units (Bridger A through E). The units were separated
lithologically by a series of "white layers", comparatively

thick and widespread calcareous ash layers. Although these

161
were technically lithostratigraphic zonations, Matthew
(1909) and many subsequent authors utilized these units as
informal biostratigraphic zonations. Wood (1934) felt that
while fossil abundance differed greatly between Bridger A
and Bridger B deposits, the fauna was basically the same.
He combined Bridger A and B into a single unit, the Black's
Fork Member, and combined Bridger C and D into the Twin
Buttes Member. He did not recognize the Bridger E as a
distinct unit. To alleviate confusion, this paper
distinguishes between Bridger A, a lithostratigraphic unit
and Bridgerian A, a biostratigraphic unit.

Robinson (1966) discovered a new fauna in the Huerfano
Valley of Colorado, intermediate in age between Lostcabinian
and Bridger A and proposed a new Wasatchian subage, the
Gardnerbuttean. Stucky (1984a) reported a similar
assemblage from the Wind River Basin. Stucky (1984a) and
Krishtalka _t _A. (1987) included it in the Bridgerian Land-
Mammal Age since the fauna has a stronger similarity to
Bridgerian than to Lostcabinian faunas. Most recently,
Gunnell et al. (1992) proposed revision of the Bridgerian
Land-Mammal Age into three subages. These are Brl
(Gardnerbuttean and "Bridgerian A"), Br2 ("Bridgerian B")
and Br3 ("Bridgerian C", "Bridgerian D" and "Bridgerian E").
To alleviate confusion and to distinguish between upper and
lower Brl, two zones are established. These are Br1.1,

(Gardnerbuttean), and Br1.2, (Bridgerian A).

 

162

Table 11. North American Early to Middle Eocene Continental
Biostratigraphy. Ma indicates millions of years before

present and is approximate.
NORTH AMERICAN LAND

Alternate Zone

 

 

 

 

EPOCH MA MAMMAL AGE ZONE Terminology
Uintan Uil Early Uintan
47.
48.
Br3 Late Bridgerian
48.
Bridgerian Br2 Middle Bridgerian
49.
E
49. Early Bridgerian
O Brl (Brl.2)
50. Gardnerbuttean
C (Br1.l)
50.
E
51. Wasatchian
N
51. Wa7 Lostcabinian
E
52.
53. Wa6 Lysitean
54.
54.
Wa5 Late Graybullian
55.
55. Wa4 Middle Graybullian
56.
Wa3 Early Graybullian
56.
Wal Late Sandcouleean
57.
WaO Early Sandcouleean
57.
P
A 58. Clarkforkian Cf3 Late Clarkforkian
L
E 58. Cf2 Middle Clarkforkian
O
C 59. Cfl Early Clarkforkian
E
N
E

163
AGE AND CORRELATION OF THE
LITTLE MUDDY-DESERTION POINT FAUNAS

Most of the vertebrate fossils collected within the
study area come from two distinct faunas. The lower
assemblage, the Little Muddy local fauna is vertically
separated from the upper assemblage, the Desertion Point
local fauna by approximately eighty meters of lacustrine
sediments. The complete interval above contains, from
oldest to youngest, the upper part of the La Barge Member of
the Wasatch Formation, the Fontanelle Tongue and lower part
of the Wilkins Peak Member of the Green River Formation, and
the New Fork Tongue of the Wasatch Formation which bisects
the Fontanelle Tongue. Table 12 provides a synopsis of the
Chronologic ranges of the mammalian taxa from the Desertion
Point-Little Muddy area.
Table 12. Chronologic ranges of mammalian taxa within the

Little Muddy-Desertion Point area. The lines indicate

the known stratigraphic range of each taxon, X's

indicate the horizons within the study area from which
species have been recovered and ?'s denote questionable

occurrences.
WASATCHIAN BRIDGERIAN
Wa6 Wa7 Br1.1 Br1.2
Perathariaa ——————————— x _________________ x--
g. comstpcki _____________________________ x--
g. innominatum ——————————— x _________________ X—-
Palaapsinopa ——————————— x ____________________
p.1utreola ? ?-X-<
Palaeictops ___________ x ___________________
g.bicuspia ——————————— x_<
Qcanppapas ----------------------------- X—-
Q. edenpnsia > .......... x__
g. priapus > __________ x-
AEQEEEEE ----------- X --------------------
1M ----------- X --------------------
1- prayballiaaua X

 

 

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Table 12 (cont'd).
WASATCHIAN BRIDGERIAN
Wa6 Wa7 Br1.l Br1.2
_ __________ x _________________ x--
9-x__
>—X—9
----------- X—<
----------- X—<
----------- X-<
----------- X-<
----------- X--------—-<
-——-< X
> ---------- X--
> —————————— x--
> ---------- X--
> ---------- X--
>-X--
>-X--
> ---------- X--
>-X--
___________ x____-_______-______-
> ---------- X-<
........... x__---_-_________-___
___________ x__-__________-___--_
- __________ x _________________ X--
>.__.' ________________ X__
----------- X—<
___________ x_<
_ __________ X _________________ x__
X > —————————— X--
>-X-<
----------- X-<
______________________ <
>-X ---------- <
___________ x----_____-____-__-__
___________ x____-_________-_____.
----------- X--—?
___________ X_<
> ——————————————————— x-—
> ---------- X--
>-X-<
>-X-<
>-X -------- X——
>—X -------- X--
>-X -------- X—-
>-X -------- X--
>-X--
----------- X—<
> ---------- X—<
___________ x-______-__________-_
___________ x_-________________-_

i r vus

Q. nitidus

Laptotomus

p. parvus
Palaeanodon
Matacheiroays
Tetrapaasalus

165

Table 12

(cont'd).
WASATCHIAN BRIDGERIAN

Wa6 Wa7 Br1.1 Brl.2

LITTLE MUDDY LOCAL FAUNA

The little Muddy Local fauna is contained by the La

Barge Member of the Wasatch Formation, the lowest

stratigraphic interval within the study area. Table 13

presents the vertebrate taxa collected from this level. The

stratigraphic relationship of the localities are presented

along with the measured sections as Plate 1

TABLE 13

Faunal List of the Little Muddy Local Fauna.

Level Locality
III 115, 118
II 114, 116

Taxon

Lepisoateus sp. indet.
Glyptosaurini indet.
Peratharium.innpmiaataa
Esthonya apatippns

Lepisoateus sp. indet.

Allopaathoaaphus sp. indet.
Trionychidae indet.

Glyptosaurini indet.
Microsypps cf. M. scottiaaua
Cantius cf. Q. ftapivoroua
Copelemur of. Q. australptataa
W sp.

Hyopsodus cf. 3. wortmani

Hyracotheriaa vasaccienae
Lambdotheriaa.popoapaciaa
Paraays of. g. excavatua

 

166

Table 13 (cont'd).

Level Locality Taxon
I 110 Lepisosteus sp. indet.

Trionychidae indet.
Glyptosaurini indet.

Xestops of. M. vegans
Amphisbaenia indet.

Palaeosinopa cf. Q. latreola
Palaeictops bicuspis

Ipaacius praybullianus
Cantius of. Q. frupivproas

Anemorhysis cf. A aaplattensis
Miacis latidans

vulpavus profeptus

Viverravus sp.

Meniscotheriaa,ppaapaap

Hyopsodus, cf. Q. minispulaa
Hyopsodus cf. Q. wortmani

Diacodexis cf. 2. secana

Hyracotherium.vasacpiansa
WW
Palaeanodpn sp.

LITTLE MUDDY LOCAL FAUNA, LEVEL I

The lowest horizon containing the Little Muddy local
fauna has been designated level I. Fifteen mammalian taxa
have been identified from the locality at this level making
it the most diverse locality within the study area.

Several of the taxa from level I (Vivarravus, vulpavua
prpfpptus, and Diacodpais) are characteristic of both the
Wasatchian and the Bridgerian (Stucky, 1984a). The
remaining are Wasatchian taxa. Mpniscptherium.ppaapaap is
known primarily from the upper Lysitean of the Piceance
Creek and San Juan basins of Colorado, and the Lostcabinian
of the Wind River and Green River basins of Wyoming (Gazin,

1965). Knipptoays depressus is known from the Lysitean

167
through the Lostcabinian (Korth, 1984) and possibly the
middle Bridgerian (Gunnell et al., 1992).

Miacia latidens is with a few exceptions, limited to
the Lostcabinian. Guthrie (1967) reported three specimens
of M. latidans from the Lysitean of the Wind River
Formation, and Matthew (1915) reported a single tooth from
the Graybullian of the Bighorn Basin. M. latidpna is only
known from the Lostcabinian (Wa7) within the Green River
Basin (i.e. West, 1973; Gazin, 1952; 1962).

Two species of Hyopsodus were identified from this
level. Hyppapdus wortmani is limited to the Lysitean (Wa6)
and Lostcabinian (Wa7) (Gazin, 1968; West, 1973; 1979).
Hyopsodus miticulus is known only from the Wasatchian (West,
1973; 1979). Palaeanopon and Hyaacotherium are known
throughout the Wasatchian (Stucky, 1984a). Several isolated
teeth referred to Cantius frupivorpaa were identified from
this horizon. This notharctine primate is known primarily
from the middle Wasatchian (Graybullian) of western North
America (Beard, 1988). Palaaiptops bicuspia is known
throughout the Wasatchian, and is a particularly common
insectivore in the Wind River Lostcabinian (Guthrie, 1971).
Palaeosinppa latraola is known primarily from the
Graybullian (Wa3-5) of the Bighorn Basin (Bown and
Schankler, 1982). Specimens previously referred to this

species by Guthrie (1971) fall out of the size range of this

taxon and are likely referable to Q. inperta or Q,

168

dipplphoides (Bown and Schankler, 1982). Anemorhysia
apataaai is unknown outside of the Graybullian of the
Bighorn Basin (Bown and Rose, 1984) possibly due to its
extreme rarity. Ipaacius praybullianus, the only early
Eocene member of the genus, is also known only from the
Graybullian of the Bighorn Basin (Bown and Rose, 1976).

Based primarily on the presence of Miacia latipena and
Mpniscptheriaa phamense, the Little Muddy local fauna, level
I is tentatively referred to the Lostcabinian. While it is
recognized that these taxa are known from older deposits
elsewhere, within the Green River Basin they are known only
from Lostcabinian strata. Additional field work may reveal

that this level is actually Lysitean in age. The age and

geographic range of Palaaoainppa cf. Q. lutraola,
Anaaprnysia aprtmani and Ipaacius praybullianpa are extended

to include the Lostcabinian (or possibly Lysitean) of the
southwestern Green River Basin.
LITTLE MUDDY LOCAL FAUNA, LEVEL II

The only common elements between levels I and II (see
below) are Qantiaa cf. Q. faapivprous, Maniscothpriaa, and
Hyaappthprium vaaacciense, taxa previously known from the

middle to late Wasatchian (Beard, 1988; Kitts, 1956; Stucky,

1984b). The most diagnostic taxon in level II is
Melting W. a species long considered the

index fossil for the Lostcabinian (Granger, 1914; Stucky,

1984a; 1984b). Paraaya excavatua is known only from the

169
Lysitean (Wa6) and Lostcabinian (Korth, 1992). Two
specimens of Copelemur cf. Q. australotutus have been
identified from this level. Beard (1988) erected this
species on two specimens collected in the vicinity of Fossil
Butte in southwestern Wyoming. There is some conjecture as
to the precise age of these strata, although they are
considered Wasatchian (Gazin, 1962; Beard, 1988). A single
/M3 of Qaataaa cf. Q. frupivorpua, a Graybullian (Wa3—5)
taxon (see above), was collected from locality BB114.
Fragments of Meniscotherium teeth were scattered over a
large portion of Locality BB114. Meniacotherium is common
from the Late Palaeocene (Cf2) of the Bighorn Basin and
Alberta, to the Lostcabinian of the Washakie, Wind River,
and Green River basins (Gazin, 1965; Stucky, 1984b).
MApapayppa appttianus is known from the Lostcabinian (Wa7)
and possibly, the Gardnerbuttean (Br1.1; Gunnell, 1989).

Level II is similar in most respects to the La Barge

fauna of Gazin (1952, 1962). It correlates with the
LEEDQQEEEELEE Range Zone of Stucky (1984a), the Wapiti II

fauna of Gunnell pt al. (1992), the Lost Cabin beds of the

Bighorn Basin of Schankler (1980), and the lower Huerfano of

Robinson (1966). The occurrence of Cantiua cf. Q.
faapivprpua with Laappptperium suggests that this taxon

survived longer in the Green River Basin than elsewhere in
western North America. Level II is clearly Lostcabinian

(Wa7) in age.

170

LITTLE MUDDY LOCAL FAUNA, LEVEL III

Two mammalian taxa have been identified from Little
Muddy level III. Peratherium innominatum is known from the
early Wasatchian through the Duchesnean of the Rocky
Mountain region (Krishtalka and Stucky, 1983). Eathonya
acutippna is, with the exception of a single specimen from
the Gardnerbuttean of the Huerfano Basin (Mckenna, 1976),
known only from the Lostcabinian (Gingerich and Gunnell,
1979). All Q. acutidens identified within the Green River
Basin has been reported from Lostcabinian localities (West,
1973; Gazin, 1962). Based on this, Little Muddy local fauna

level III is tentatively referred to the Lostcabinian.

DESERTION POINT LOCAL FAUNA

The Desertion Point local fauna was collected from the
Whiskey Butte Bed of the Bridger Formation, the Craven Creek
Bed of the Laney Member of the Green River Formation, and
the upper portion of the Upper Member of the Wasatch
Formation. Table 14 presents the vertebrate taxa collected
from this level. The stratigraphic relationship of the
localities is presented along with the measured sections as
Plate 1.
DESERTION POINT LOCAL FAUNA LEVEL I

Similar to the Wapiti IV local fauna of Gunnell et al.

(1992), level I is comprised of a single species, anapayaa

 

Level

171

TABLE 14

Faunal List of the Desertion Point Local Fauna.

Locality
35, 37,
38, 44

Taxon

Lepisosteus sp. indet.
Amia sp. indet.
Echmateays sp. indet.

Echmatemys septaria
Merges;

Alligatoridae indet.

Allopaathosuchus sp. indet.
Diplocyaodon sp. indet.
Crocodylus affinia

W
Glyptosaurini indet.

Xestops sp. indet.
glen-119mm
Peratherium coaatocki
Q. innominatum

cf. Apateays sp. indet.
chnopapas openensis
3m
Notharctus appiaapa;
Smilodectes mcprewi
washakius insipais
Viverravus pracilis
Hyrachyas modestus
Sciuravus nitidua
Metacheirpays

172

Table 14 (cont'd).

Level Locality Taxon
IV 12, 19, 36 Lapiaosteas puneatua
69, 70, 74 Lapisosteas sp. indet.
76, 77, 109 Amie sp. indet.

Ictaluridae sp. indet.
Baena arenosa

__emLBchmat 8 m
Echmateays ayominpensis
Ephmateays sp. indet.

cf. Platypeltis sp. indet.
Baptaays fluviatalis

Bapteays sp. indet.
Alligatoridae indet.
Allopaathosuchus sp. indet.
Diplocyaodon sp. indet.
WM

Pristichaapsua
Glyptosaurini indet.
Glyptosaurus aylvestris
Qpatppa sp. indet.
Peratherium innominataa

Microsyops slogans
Smilodectes sp.
Motharctus robinaoni
paomys carteri

Omoays cf. p. carteri
cf. Orohippus pumilaa
Palaeosyops cf. Q. QpatiaaAia
Hyaachyas modestua
Qciuravus nitidus;
Metacheiroaya sp.
Tetrapassalua sp.

173

Table 14 (cont'd).

Level Locality Taxon
III 13, 13w, 68 Lepisosteus cuneatus
75 Lepisosteus sp. indet.

Ania sp. indet.
Ictaluridae indet.
Baena arenosa
Echmateays septaria
Echmatemys sp. indet.
Bapteays fluviatalis
Bapteays sp. indet.
Allopaathosuchus sp. indet.
Crocodylidae indet.
Magi—Ilia
Parasauromalus plseni
Glyptosaurini indet.
Xestops. sp. indet.

Microsyops elegans
Hyopsodus cf. Q. minispulaa
prohippus sp.

Qeleneletes sp.

Sciuravus nitidus

Leptotomus parvus

II 14, 51, 96 Lepisostpus sp. indet.

97, 103, 104 Echmateays of. Q. cibpllensia
Bapteays sp. indet.
Glyptosaurini indet.
Palaeosyops cf. Q, fontiaalia
Leptotpmua sp.

I 117 Hyraphyaa modestas

174
modeatas. Hyrachyas is known from the earliest Bridgerian
to well into the Uintan (Radinsky, 1967; Stucky, 1984b;
Woodburne, 1987). West (1973) reported both Hyaachyas and
Lambdothpriaa.from a single locality that spans over sixty
meters of stratigraphic section. It is uncertain if the two
taxa came from the same horizon. Until conclusive evidence
of overlap in the ranges of Qaappptppaaaa and anappyaa is
provided, Hyrachyas can be retained as a diagnostic
Bridgerian taxon. Level I is interpreted as Gardnerbuttean
based on the presence of Hyaachyas modestas, and its
stratigraphic position (see Level III below).
DESERTION POINT LOCAL FAUNA, LEVEL II

Two mammalian taxa have been identified from Level II,
Laptptpmua sp., and Palaeosyops cf. Q. fontinalis. Q.
fpntiaalia is indicative of an early Bridgerian (Brl)
designation (Gunnell and Bartels, in press; Gunnell et al.,
1992). Laptotamua is first recognized from the
Gardnerbuttean (Korth, 1984; Stucky, 1984b).

Echmataaya is a common element in Desertion Point local
fauna levels III through V. The two species known from
these levels, Q. septaria, and.Q, ayominpenais are unknown
from.the lower levels, including II. A single specimen of
the poorly known emydid Ephmatpaya cf. Q. cibpllanaia was
collected from level II. This taxon is not present however
in the substantial collection of lower vertebrates collected

from higher levels within the study area. Further study may

175
confirm that the presence of Q. cibollensis is indicative of
pre—Bridgerian A deposition. Level II is interpreted as
early Gardnerbuttean based on the fauna of the overlying
level III (see below).
DESERTION POINT LOCAL FAUNA, LEVEL III

Six mammalian taxa have identified from level III. All
are indicative of the early Bridgerian. Sciuravus nitidus
first appears in the Gardnerbuttean and is common throughout
the Bridgerian (West, 1973). Microsyops slogans is known
from.the middle Bridgerian of southwestern Wyoming (Gunnell,
1989). A single specimen from the Gardnerbuttean of the
Willwood Formation of Wapiti Valley (Gunnell et al., 1992)
and several specimens from the Bridger A and B of the
Aycross Formation of Hot Springs and Park County (Bown,
1982; Gunnell, 1989; Gunnell et al. 1992) have been referred
to M. plepana.

The taxa from this level are indicative of the early
Bridgerian (Brl). It is difficult to assign this level to
either the Bridgerian A or to the Gardnerbuttean with the
available information. Qelenaletpa is poorly known, the
only specimens of known provenance outside the study area
were collected from the Gardnerbuttean (Brl.l) QaAappayppa
ppapaaaa Zone of Stucky (1984a; 1984b). Qyppappaa
minispulas and Orohippus are common Bridgerian taxa.
prohippaa is also known from the late Wasatchian (Korth and

Evander, 1982; Stucky, 1984a; 1984b). Laptotpmus parvua is

176

known from the upper Huerfano Formation (Gardnerbuttean;
Robinson, 1966) and is common throughout the middle
Bridgerian of the Green River Basin.

Based primarily on the presence of Seleneletes, Level
III is interpreted as Gardnerbuttean (Br1.1). The A
geographic range of Qeleneletes is extended to include the
southwestern Green River Basin.
DESERTION POINT LOCAL FAUNA, LEVEL IV

papaya carteri and.Washakius insipais are first known
from the Bridger A of the southwestern Green River Basin
(Gunnell, pers. comm.), and range through the end of the
Bridgerian in this area. Notharctus rpbinspni is known only
from the early Bridgerian of the Green River, Huerfano, and
possibly the Bighorn basins (Gingerich, 1979). Orphippas
pumilaa is known from the lower (McGrew and Sullivan, 1970)
and middle Bridgerian (Gazin, 1976) of the Bridger Basin,
and from the Gardnerbuttean Aycross Formation of the Wind
River Basin (Stucky, 1984b). Tetrapassalas is known from the
middle Bridgerian of the Bridger Basin (Stucky, 1984a).
Qmilppectea is known throughout the Bridgerian of North
America.

Based primarily on the co-occurrence of Nptharctaa
robinapni and Omoaya carteri, level IV is interpreted as
Bridger A (Brl.2). The known range of Tatrapassalus is

extended to include the early Bridgerian.

177

DESERTION POINT LOCAL FAUNA, LEVEL V

Level V is the highest interval within the study area.
Seven mammalian taxa not found in any of the lower intervals
have been identified from level V. Two species of
Qpaappapaa, Q. prisons, and Q. edenansis are found at this
level. Both of these species are known from the Bridgerian
A (Br1.1) of the northeastern Green River Basin (West, i
1973), the Gardnerbuttean (Brl.2) of the Huerfano Basin
(Robinson, 1966), and the middle Bridgerian (Br2) of the
southern and eastern Green River Basin (McGrew, 1959).
Viverravua pracilis is a common taxon in the early and
middle Eocene of the Rocky Mountain region (West, 1973).
Parathprium comatocki is common throughout the early and
middle Eocene of wyoming, Colorado, New Mexico, and Texas
(Krishtalka and Stucky, 1983). Qmilodectes mcprewi is known
from the Gardnerbuttean of the Huerfano Basin and the
Bridgerian A of the Green River Basin (Gingerich, 1979).
Metachairpaya is known from the early and middle Bridgerian
(Brl-Br2) of the southwestern Green River Basin (Gunnell and
Bartels, in press; Stucky, 1984a). washakius insipaia is
known primarily from Bridgerian A (Brl.2) and Bridgerian B
(Br2) within the Green River Basin (Gunnell, in prep.).
Based primarily on the co-occurrence of Qmilodactas appaapi,
waapakius insipais, and chnopapas, Level V is referred to

Bridgerian A (Brl.2).

178
STRUCTURAL AND SEDIMENTARY HISTORY

The Green River Basin (Figure 1) is bounded by Laramide
uplifts and mountain systems to the south east and north.
The basin is filled with approximately 3,000 meters of
Tertiary strata (Blackstone, 1955; Sullivan, 1980).
Laramide tectonism commenced in the Late Cretaceous, and
although some movement continued through the end of the
Eocene (Chadronean), it was effectively completed in the
Early Eocene (Wasatchian, Lillegraven, 1992). The west
margin of the study area is formed by the Wyoming Overthrust
Belt, a complex of thrust fault mountains. Initial movement
began in the early Mesozoic (Rubey, 1955) with major
deformation continuing (locally) into the early middle
Eocene (Andermann, 1955).

Formation of the Green River Basin commenced in the
Late Cretaceous with initial downwarping initiated by
Laramide tectonism and augmented by sedimentary loading from
the Overthrust Belt (Shuster and Steidtmann, 1988).
Subsidence continued well into the Tertiary (West, 1976).

The sedimentary history of the early to late Eocene of
the Green River Basin centres around the multiple
regressions and transgressions of Eocene Lake Gosiute, a
large shallow lake that occupied the centre of the basin.
The deposits of this lake, now represented by the Green
River Formation, is one of the largest accumulations of

lacustrine sedimentary rocks in the world (Grande, 1984).

 

179
Lake Gosiute is currently thought to have been a playa lake
complex (Surdam and Wolfbauer, 1975). Lake Gosiute was set
in the centre of a large, relatively flat intermontane
plain. The abundance of fine-grained material extending
from the center to the periphery of the basin indicates that fl
"the original dip (gradient) probably did not exceed 1 or 2 F
feet per mile except in a rather narrow belt adjacent to the
mountains" (Bradley, 1964 p. A16). Minor fluctuations in
water depth would therefore have resulted in the extensive
inundation of the lowlands adjacent to the lake.

In periods of drought the lake became quite restricted
and likely very saline (Surdam and Wolfbauer, 1975; Grande,
1984). The lake was eutrophic ( characterized by abundant
organic material and a seasonal oxygen deficiency in the
lowest layers, usually shallow) as is evidenced by the
abundant organic mudstones, oilshales and periodically
extensive algal limestones produced at different stages in
its history (Surdam and Wolfbauer 1975).

Lake Gosiute likely began as a system of small lakes,
swamps and ponds on the subsiding Wasatch Plain (Surdam and
Wolfbauer, 1975). Expansion of the lake throughout most of
the Bridger Basin is signified by the Luman Tongue of the
Green River Formation, which does not crop out within the
study area. A major regression of the lake is represented
by the fluviatile red-bed deposits of the La Barge Member of

the Wasatch Formation. Figure 18 shows the relationship of

 

Figure 18.

180

Correlation chart of lithostratigraphy,
fossil vertebrate localities, faunal levels,
and biostratigraphy. DPLF denotes Desertion

Point local fauna, LMLF denotes Little Muddy
local fauna.

181

 

 

 

 

 

 

 

 

 

namnnuau
ummarmnruv Locumr mm. mm.xflcu"y
no
was"! um: I!»
- - . DPLF v u
‘ um: FOIIATION 1.1.? uoas.m.onm '
, cum: cam no I macaw: a
, mm lam "I! Iv n
_ _- - (um)
. emu mu Ion-Anon (I
1 F t
. untm '
J {333:3 uom '
3w 1"? 1'1“:
. 4'
. um lam Elm:
4 mm
4 numnu untn
. mum summon mu
W g:§§umm”, ummmwnuu
. wuxfll‘fin
E on.»
. W
m m E
m | ' . ‘ - I ”k v .‘.
Imam Iron-men ~««‘ ,1-
‘ mum nu lulu m..."
'1 ‘33—— :—
. ummnwnwmmumu
. _r'm val __j_________
*Immmwunmwt
‘ mu um summon
m mu mm:
'0" m m Ion-moo
. mummu ramus
um um mumou
a p- - - ------ - - —
‘ 1484.0! mm
‘ .-.-.-‘- u as»: um I:
. mum: FOIIA‘IIOI w
A
- 3
sum:
" um " g loam
1 «un
.--- A
51':- nm um I L

 

 

 

 

 

 

 

 

 

Figure 18

 

182
the lithostratigraphy, biostratigraphy, and fossil
vertebrate localities within the study area. The sediment
that comprises the La Barge Member is derived from active
faulting in the Overthrust Belt west of the study area
(Lawrence, 1965) . The Little Muddy local fauna (see above,
Table 13) is found entirely within the La Barge Member.

The thick gastropodal limestone at the base of the
Fontanelle Tongue represents another major transgression of
Lake Gosiute. The absence of stromatolites in this unit may
indicate that the transgression was rapid (Lawrence, 1965) .
The abundance of Goniobasis tenera in this layer may
indicate that much of unit was deposited in the littoral
zone (Hanley, 1976) . Fragmented elements of fish are also
COmrnon in this layer. Surdam and Wolfbauer (1975) consider
the Fontanelle Tongue representative of a maximum stand of
Lake Gosiute.

The overlying Wilkins Peak Member is characterized by
organic rich mudstones interbedded with algal limestones.
At this time the lake vacillated from freshwater to
hYPersaline conditions as is indicated by the abundant
interbedded stromatolitic limestones and organic shales
(Surdam and Wolfbauer, 1975) . Hypersaline water and the
absence of aquatic grazers are essential for the
p"-'eServation of cryptalgal structures (Logan et al., 1974;

Surdam and Wolfbauer, 1975) . Chemically enriched water may

183
explain the absence of fossil vertebrates, even fish, within
most of this layer.

Periodically, during the deposition of the Wilkins Peak
Member, the lake retreated far enough for the study area to
be eJ-cposed. This is evidenced by mudcracks in many of the
shales overlying the stromatolitic layers (Surdam and
Wolfbauer, 1975) . The presence of Qmppm W, a
tapiroid perissodactyl, at locality BB117 near the base of
the vvilkins Peak Member is additional evidence that the
study area was exposed at this time.

Qmpama is also indicative of Bridgerian deposition.
The presence of a Bridgerian index taxon in strata
immediately above, and Wasatchian taxa below the lacustrine
beCis of the Fontanelle Tongue indicates that the Wasatchian-
Bridgerian boundary is obscured within the Bridger Basin by
a major transgression of Lake Gosiute. This single specimen
0f afiachfla along with several unidentifiable turtle
fragments constitutes Desertion Point local fauna level I.
The presence of diagnostic Bridgerian taxa over 200 meters
bEJ-Ow the base of the Bridger Formation clearly shows that
the Wasatchian-Bridgerian biostratigraphic boundary is not
correlative with the Wasatch-Bridger lithostartigraphic
boundary in the southwestern Green River Basin, the type
area of both of these Land Mammal Ages.

Major tectonic activity in both the Overthrust Belt to

the West and in the Wind River Mountains to the northeast

 

184
supplied the sediment for the litharenites of the New Fork
Tongue which interbed with the lacustrine strata of the
Wilkens Peak Member (Lawrence, 1965) . The intertongueing of
the fluvial beds of the New Fork Tongue and the lacustrine
beds of the Wilkens Peak Member may indicate that the New
Fork Tongue represents a delta (Lawrence, 1965) .

Renewed tectonic activity of the Uinta Mountains to
the south resulted in the deposition of the fluviatile beds
of the Upper Member of the Wasatch Formation (Lawrence,
1965) . The interbedded red-gray fluviatile deposits of the
Wasatch Formation may indicate periodic inundation followed
by desiccation and an interval of non-deposition, allowing
for E M oxidation of the iron-rich sediments (Braunagel
and Stanley, 1977; Roehler, 1965). Shorter periods of
deSiccation and non-deposition resulted in the predominance
0f mottled red mudstones with thin, discontinuous algal
limestones and thick channel sandstones in the lower part of
the Upper Member indicating a terrigenous environment more
Proximal to the shore of Lake Gosiute than in the upper
Part . Only a few vertebrate fossils have been recovered
from the lower part of the Upper Member of the Wasatch
Formation. Of these fossils, only a single specimen of
W cf. Q. pibollpnsia has been identified. All
Other fossils, mammals and reptiles alike, are characterized

by a high degree of post-depositional corrosion. Desertion

185

Point local fauna level II was collected from the lower

11alf of the Upper Member of the Wasatch Formation.

The less mottled, more colourful mudstones of the upper

part of the Upper Member were deposited in a better drained

jfluvial environment. While few fossils have been identified

from most of these layers, they are typically much better

1;:reserved than specimens from the lower part of this unit.

The mudstones at the top of the Upper Member of the Wasatch
Formation have produced a small but diverse and diagnostic

assemblage of fossil vertebrates designated Desertion Point

local fauna level III (Table 14) .

The upper boundary of the Upper Member of the Wasatch

Formation signals another transgression of Lake Gosiute.
These deposits have been termed the Craven Creek Bed of the

Laney Member of the Green River Formation (Sullivan, 1980) .

Within the study area, this transgression coincides with a

major deposit of ash, likely from the Absaroka volcanic

field in the northwest corner of Wyoming. This ash deposit

buried large amounts of organic material preventing rotting,
and resulting in the tuffaceous lignitic mudstone which
marks the upper boundary of the Wasatch Formation within the

field area. Many of the specimens incorporated into

Desertion Point local fauna level IV were collected at the

top of this tuffaceous lignite. The interbedded lignites,

gray —green mudstones, discontinuous algal limestones, low-

grade oil shales and cross—bedded channel sandstones

186
indicate that the Craven Creek Bed is a mixture of
lacustrine, paludal, and fluviatile deposition (Roehler,
21965) . The presence of both fluvial taxa such as
glyptosaurine lizards, Anosteira, Allogn_athosuchua, and
perhaps Bapteays fluviatalis and lake to lake-margin taxa

such as Crpcodylus, Baena arenoaa, and possibly A_myda. from

 

tzhis layer also suggest frequent environmental turnover.
The last major event in the study area was the regression of
Lake Gosiute, resulting in deposition of the fluviatile
deposits of the Whiskey Butte Bed of the Bridger Formation.
JFas is indicated by the light gray to gray-green mudstones
and siltstones, the Whiskey Butte Bed was deposited in the
lowlands adjacent to the lake. The greenish tinge in most
of the mudstones is indicative of the reduction of iron in
poorly drained conditions (Roehler, 1965) . Desertion Point
local fauna level V was collected from the Whiskey Butte

bed.

PALEOENVIRONMENTS AND PALEOECOLOGY
The following comprises a brief interpretation of the
paleocology and paleoenvironments of the various lithologies
wi thin the study area. Interpretations of paleogene
paleoenvironments generally utilize floral remains rather
that: terrestrial vertebrates since many plant genera and

f - . . . .
amllles present in the Paleogene are still alive today

187

while vertebrate (particularly mammalian) generic and

familial turnover rates are comparatively rapid.

PALEOBOTANY AND GENERAL PALEOECOLOGY

Although the paleobotany of the Green River Formation
(Df Utah and Colorado is well known, collections from the

Green River Basin (ex. Hayden, 1871; Lesquereaux, 1878;

1898, and Knowlton, 1923) have little

1883; Newberry, 1883;
stratigraphic or geographic control. These collections do

not appear markedly different in composition than

collections from the Uinta Basin (MacGinite, 1969) . Plant

macrofossils from the study area are limited to fragments of

permineralized wood, carbonized root traces in many of the

mudstones, fragmented plant debris in the lignitic ash layer

at the base of the Craven Creek Bed of the Laney Member of

the Green River Formation, and a single hackberry seed

(Genus Cpltia) from the La Barge Member of the Wasatch

Formation.
Based on floral analysis of the Green River Formation
in the Uinta Basin of northeastern Utah and northwestern

Colorado, MacGinite (1969) suggested a warm temperate to

Subtropical environment with savannah type vegetation

Conditions proximal to the lake and subhumid shrub to open

forest conditions at slightly higher altitudes.

Precipitation was highly seasonal with abundant rainfall in

t . . . . . .
he spring and drought conditions in the fall (MacGinite,

l . . . .
9 6 S) . Annual preCipltation was 24—34 inches (60—85cm) at

188
Zlake level, and 38 inches (95cm) in the surrounding uplands
(Bradley, 1963). Based primarily on the distribution of
IEocene volcanic ash deposits, prevalent wind direction is
t:hought to have been from the north (Clark et a1, 1967).
The size of Eocene Lake Gosiute would have had a strong
Geffect on the climate of the Green River Basin. During high
.sstands of the lake, it is probable that the local climate
1uvas comparatively equitable, with more moderate high and low
t:emperatures, and higher humidity. When the lake was more
:zrestricted in size, annual temperatures reached greater
«eaxtremes and humidity was lower. It is uncertain to what
«eaxtent this climatic variance affected faunal composition.
PALEOECOLOGY- LITTLE MUDDY LOCAL FAUNA
The La Barge Member of the Wasatch Formation was
deposited in drier times than the overlying strata within
t:131e study area. Lake Gosiute was restricted to the centre
<C>1E the Green River Basin, far to the east of the study area.
'Jfir1ea Little Muddy local fauna, derived exclusively from this
J—Eizywar, was dominated by adapid primates and condylarths.
While adapid primates are comparably common throughout
tiklfia study area, condylarths are almost nonexistent in the
C)“"‘EE-'Zl::‘lying Wasatch and Green River formations. Two
czc>l:l<i1ylarthan genera have been identified from the La Barge
Lb1€3111123er. Most authors (ex. Gazin , 1965; Simpson, 1948)

c: . . .
(DIELEESider Mgniscogherium characteristic of an open,

£3
Eijk’VEELnnalike environment. Although Gazin (1968) did not

189
consider onnsodus diagnostic of any particular environment,
it appears that this small condylarth may have some
paleoecologic significance. Hgopsodus is among the most
common mammalian taxa collected from the Bridgerian B (Br2)
of the southwestern Green River Basin (West, 1979) , and from
the late Wasatchian of the western Green River Basin (Gazin,
1952; 1962) . While it remains an important constituent
<jiuring the Bridgerian A (Brl.2) of this area (Gunnell and
Bartels ,in press), it is less evenly distributed than in
earlier and later times (Gunnell, pers. comm.) . Although
the exact environmental or ecologic reason is uncertain,
preliminary comparison of localities where it is common and
those where it is not may indicate a preference for drier
locales such as open forest or savannah (Gunnell, pers.
comm.) . This is consistent with the conclusions of Pledge
( 1969) and analysis of the distribution of W within
the study area. The artiodactyl Diggodggis, and the
perissodactyls Lambdotherium and eracotherium comprise the
balance of the ungulate taxa. The comparative scarcity of
perissodactyls and plethora of condylarths, in both overall
abundance and taxonomic diversity, in the Little Muddy local
fauna may reflect incompatible habitat preference. The
condylarths preferred drier, more open country; the
peri ssodactyls favoured the swampy woodlands adjacent to the
Shores of Lake Gosiute and the myriad streams and ponds on

i
t S periphery.

 

 

190

The Little Muddy local fauna is also characterized by
an abundance of arboreal and semi—arboreal taxa such as the
insectivores Palaeosinopa and Palaeictogs, the marsupial
Pgrathgrium, the proprimates Iflcius and Microgxons, and
the primates Cantius, Conelemur, and Anemorhxgis. Fossorial
taxa such as the edentate Palaeanodon, the tillodont
Esthonfl, and an indeterminate amphisbaenid are also
present.

A single hackberry seed (Genus Celtis) was recovered
from Little Muddy local fauna level I. Cglgig prospers in
dry conditions and is intolerant of shade (Taggart, pers.
comm.), suggesting an open forest or savannalike environment
The occurrence of the gastropods Oreoconus and Holgspira
indicate standing water in the form of marshes and small

ponds (Hanley, 1976) . Abundant remains of trionychid

turtles, especially Aspiderites, glyptosaurine lizards and

teeth of the alligator Allgmghosuchug are indicative of a

fluviatile environment (Bartels, 1993) .

Overall, the Little Muddy local fauna occupied a warm,

comparably dry setting, distal to the shores of Lake
c3"Osiute. Extensive open forests were present on a well-
drained substrate as is evidenced by the presence of diverse
fossorial and arboreal taxa and abundant fragments of

permineralized wood.

 

191

PALEOECOLOGY- DESERTION POINT LOCAL FAUNA

As indicated above, few fossils have been collected

:from the thick sequence of sediments separating the La Barge
Ifiember of the Wasatch Formation in the weSt, and the upper

Ipart of the Upper Member of the Wasatch Formation in the

eeast. The Fontenelle Tongue and Wilkens Peak Member of the
C3reen River Formation represent frequent, minor lake

(see above), indicating a net increase average

:incursions
The lower part of the Upper Member of the

aannual rainfall.
170asatch Formation was characterized by a dominance of

t:errigenous conditions, although sedimentation was more

jfrequent and the substrate less well-drained than in the La

JEBarge Member and the upper part of the Upper Member of the
thfasatch Formation. Little can be said about the local
(eerrvironment at this time.

The upper part of the Upper Member,
and the Whiskey Butte Bed

the Craven Creek

Bed of the Green River Formation,

c>sz the Bridger Formation represent frequent vacillation

be tween terrigenous and lacustrine dominated conditions. The

abundance of aquatic and amphibious taxa from the upper
laYers of the Upper Member of the Wasatch Formation and the
CIITEixaen Creek Bed of the Laney Member of the Green River

F03|:“I:1-1ation indicates the close proximity of the shoreline of

Lake Gosiute. Turtles and crocodiles are represented by
I1“airlmr'large, diverse forms. Fish are common and also reached
large sizes. Although only three taxa have been identified,

 

 

192

it is possible, indeed likely, that many forms existed since

teleosts are difficult to identify with only fragmentary

remains.
Most of the turtle specimens collected within the study

area were comprised solely of carapace and plastron

even those with articulated

elements. Few specimens,

shells, possessed any associated limb or cranial material.

:Most likely, with subsidence of rigor mortis and the
relaxation of striated skeletal muscle, the head and the
limbs were extended out from the body. As decomposition
«continued, small scavengers were attracted and initiated
Imechanical destruction of the corpse. Birds and most other

<2arrion-eaters were limited to portions that could be
zremoved.through.the front or back openings of the shell.

jéglthough bird fossils have not yet been identified from the

sstzudy area, Grande (1984) reported several fine specimens
15t:rom.fossil quarries in the Green River Formation elsewhere

and indicated that footprints of

jL1:L the Green River Basin,
Scavenging arthropods

aquatic waterfowl are not uncommon.
LLii.Jcely completed the removal of soft tissue, in most cases
VV:i.t:hout seriously damaging the carapace or plastron.
ESCZEafivengers turning dead individuals on their backs for

eaéiésaier access to shell openings may explain why most turtles

VVEEJE‘GE found lying plastron up.
The presence of abundant pulmonate gastropods such as

lilEEIEEEQJ and Biggphlgria, are indicative of poorly drained

 

193
Imarshy wetlands (Hanley, 1977). Fossorial taxa such as the
«edentates Metacheirogxs and Eggggngggglgg and arboreal taxa
:such as the primates Omogxs, Notharctus, and Smilgdectgg,
'the proprimate Microszogs, and the marsupial Peratherium
salong with abundant specimens of the anguid lizard
(Slxntgsguggs combined with the plethora of large aquatic and
aamphibious taxa indicate well-developed forests in close
Iproximity to Lake Gosiute. Abundant localized lignitic and
(organic mudstone deposits interspersed with a plethora of
:small channel sandstones indicates a frequently flooded,
Itaeavily forested environment, with abundant swamps, ponds,
sand streams on the lowlands at the edge of Lake Gosiute.

The lower Bridger Formation represents a return to
1;xredominantly terrigenous conditions, This is confirmed by
t:11e abundance of terrestrial taxa such as edentates
( Metacheiroys) , insectivores (Sgenonaggs and M) ,

marsupials (Peragherium), primates (Notgrcgus, W,
and Waggkiug) , and squamates (Xegtons and the boid
W) . Comparatively short lake incursions allowed for
tir1<e invasion of aquatic taxa such as Lepisosteus and.gg;;,
and amphibious taxa such as the larger crocodilians.

The co—occurrence of the insectivores figgggngggg (two
Species) , and Mg, the marsupial Pgrgtherig (two
Species), the primates gotharctus, Smilggecggg, and
!!£¥é§:;3;5;g§, the only snake from the study area, leggggggg
IEEESEQEEQQ, and the lizard Xesggps are indicative of a

194
tierrestrial habitat. The presence of Baena arenosa, and
Exossibly Amxda are also suggestive of the lowlands proximal
tx: Lake Gosiute. Abundant fossil logs indicate well-
Cieveloped forests in the lowlands. This fits well with
(Bunnell and Bartels' (in press) interpretation of a humid,
<:losed, heavily forested environment with abundant swamps,
:small ponds and meandering streams proximal to the shore of
Lake Gosiute .

Overall, the Desertion Point local fauna occupied a
swarm, comparably moist environment, proximal to the shores
(of Eocene Lake Gosiute. Interbedded lignites, channel
:sands, and lacustrine muds along with a mixture of aquatic,
aamphibious and terrigenous taxa indicate frequent
eanvironmental turnover caused by minor fluctuations in the

leevel of Lake Gosiute. Abundant fossilized logs at the base

of the Bridger Formation indicate extensive forests in the

.J_c>wlands adjacent to the lake.

DISCUSSION AND SUMMARY
The Wasatchian-Bridgerian boundary is best known from
the Huerfano Basin (Robinson, 1966) , the Wind River Basin
( Stucky, 1984a; 1984b), the Bighorn Basin (Bown, 1982;
Gsillinell et al. 1992) and the northeastern Green River Basin
(IOTGest, 1973; West and Dawson, 1973). In most cases, the

boundary is marked by a transition zone, combining

195
characteristic taxa of both the latest Wasatchian (Wa7) and

the earliest Bridgerian (Brl).

The present study has shown that within the

southwestern Green River Basin the Wasatchian—Bridgerian

boundary is represented by about eighty meters of
essentially unfossiliferous lacustrine sediments that
reflect the intrusion and recession of Eocene Lake Gosiute.

This interval saw considerable change in the vertebrate

fauna of the area. The following paragraphs incorporate

these new data with previous studies of the region.
established two distinct faunal zones

The lowest, the Lflgghgrium

The upper he termed the

Stucky (1984b)
above and below the boundary.

range zone is Lostcabinian in age.

Pglaeosxons (=Eotitanops) borealis range zone (also marked

by the appearance of Enachms) . In the Wind River and
Huerfano basins these two faunas do not overlap. West

( 1973) reported Enachms and Lambdotherigg from one
and Palaeogxops borealis and Lmdgghgrim from

locality,
another locality in the northwestern Green River Basin.

Both localities represent approximately 60 meters of
S tratigraphic section however and it is not known where in

the section any of the fossils were collected. Additional

e‘7‘idence is needed before Hyrachmg and Palaeosxong can be
considered contemporaneous taxa of mm. The

Wapiti II local fauna of Gunnell §_t_ a], (1992) contains both

W and Eotitanops borgglis and is the only place

196

where these two animals are known to co-exist. This may

indicate that either the Wapiti II local fauna is slightly

Blounger than Lostcabinian localities elsewhere or that basin

tnargin faunas differ from central basin faunas (Gunnell gt

al., 1992) . Within the field area, specimens of

lambdggherium and Enachms were collected from localities

separated by more than 100 meters of stratigraphic section.

Palaeogxons is first known from approximately 120 meters

above Mm.
Unlike the classic Gardnerbuttean (Brl.1)

and the Palaeosxons boreglig
1984b),

in the

I-Iuerfano Basin (Robinson, 1966)

assemblage zone of the Wind River Basin (Stucky,

:strata assigned to the Gardnerbuttean within the study area
eare characterized by an absence of Wasatchian forms.

Analogous to the Gardnerbuttean fauna described by West

( 1973) , the Desertion Point Gardnerbuttean resembles a

depauperate Bridgerian fauna rather than a mix of Wasatchian

and Bridgerian forms. The difference between the

(3:21rdnerbuttean of the Green River Basin and that of the
IBLi.ghorn, Wind River and Huerfano Basins is largely due to
i ts depositional history.

The early Tertiary sedimentary history of the Bighorn,
Wind River and Huerfano basins is dominated by floodplain,
s'Zl‘eam, alluvial fan, and occasionally volcaniclastic

deposits (Gingerich, 1989; Gunnell et al. 1992; Robinson,

1 9 6 6; Stucky, 1984b). The Palaeogene of the Green River

197

Basin was dominated by transgressions and regressions of an

extensive lake system known as Lake Gosiute. This lake

System periodically inundated most of the available

terrestrial habit within the basin. The Green River Basin,

therefore, frequently needed to be repopulated by

terrestrial plants and animals.

Rather than a transitional fauna, the Wasatchian-

:Bridgerian boundary is marked by a 80 meter hiatus

representing a major transgression of fossil Lake Gosiute.
'I‘his transgression is marked by the thick lacustrine

deposits of the Fontanelle Tongue of the Green River

Formation. The subsidence of the lake is marked by the

<fleposition of the Wilkins Peak Member. By the time the lake

had subsided to the minimum represented by the terrigenous
beds of the Upper Member of the Wasatch Formation, most

Wasatchian forms had become extinct, and the area was

repopulated by early Bridgerian animals.
The Wasatchian-Bridgerian boundary is a time of

significant faunal change, particularly among mammals, at

both the generic and ordinal level. Out of a total of 34

mammalian genera represented within the study area,

only
5 o1:er Pergtherium, Microgxgng, Viverravus, and Hgonsodus are

Shared in common between the Little Muddy and the Desertion

PO int local faunas. Table 15 presents a breakdown of the

Inallfl'unals within the study area and their relative abundance

198

Table 15

IPercent composition of the Little Muddy local Fauna. The
ruinimum number of individuals is used in calculating ordinal

19ercentages.
number of specimens.

Minimum number
of individuals

:Marsupalia

Perathgrigg innominatum
Insectivora

Palaeosinona cf. g. lutreola

Palaeictops bicuspis
:Proprimates

Iggggigg graxbullianus

Microsyops sp. indet.
Primates

antiug cf. Q. frugivorous
Copelemur cf. Q. australotutus

Anemorhzgis cf. A” sublettensis

(Zreodonta
Carnivora
Miacig latidens
yglnavus profectus
Viverravus sp. indet.
C2c>ndylartha

Meniscotherium chamense
Meniscotherium sp. indet.
Hzopsodus miticulus
Hzopsodus wortmani

T i llodontia
Bethany; acutidens

Ar tiodac tyla
Diacodexis cf. 9. secans

Perrisodactyla
Hyracotherium vasacciense
ngpdothgrium.nonoagacium

R0 dentia
Knightggxs depressus
Parggxs cf. 2. excavatug

In C ertae sedis

Palaeanodon sp. indet.

Totals

LA)

(9)

U1

FJHFARJHPJFJW+4F*H£UF*HtQk)mr4F‘NFJFHflPAH

The number in parentheses indicates the total

Per cent of
total fauna
2.9

14.7

14.8

11.9

 

100.0

199

Table 16.

IPercent composition of the Desertion Point local Fauna. The
ruinimum number of individuals is used in calculating ordinal
19ercentages. The number in parentheses indicates the total
number of specimens.

 

Minimum number Per cent of
of individuals total fauna
:Marsupalia 3 6.1
Pergtherium,gggg§gg§i l
g. innomigggum 2
Insectivora 3(4) 6.1
Agategxs 1
ggenonaggg gdenensig 1
g. prisons 1(2)
.Proprimates 3(4) 6.1
Microgxgng glegans 2
Microsyops sp. indet. 1(2)
jPrimates 8(11) 16.3
flotharctgg robinsoni 3(4)
gmilodectes mcgrgwi l
Omogys carteri 2
washakigs insignia 1
Creodonta 1 2 . O
(Searnivora 2 4.1
‘Vivgrraggg grggilis l
C2<3ndylartha l 2.0
Hyopsgdgs miticulus 1
'I?eaeniodontia 1 2.0
I?earrisodactyla 14(20) 28.7
Qrohinnus gumilus l
Orohinpus sp. indet. l
Palaeoszops of. g. fontinalig 2
Hzrachygs mgdestus 4
ggleneleteg sp. nov. 3(5)
Rodentia 10(12) 20.5
ggiuraggs nitidus 5(7)
Lentotomus cf. L. Huerfgnengis l
L. parvug l
Incertae Sedis 3 6.1
Mggachgirogxs sp. indet. 2
Tetragasgalug sp. indet. 1

Totals 49 (61) 99.9

 

200
iri the two faunal zones. The total sample is too small for

a: statistically significant analysis, but some interesting

t:rends are apparent.

While no primate genera are shared between the
VNasatchian and Bridgerian within the study area, generic
diversity and overall abundance remain relatively constant.

Perissodactyls comprise almost one third of the Desertion

Point local fauna, and less than a tenth of the Little Muddy

local fauna. Conversely, only a single condylarth has been

identified from the Desertion Point local fauna, while they
comprise approximately 15% of the Little Muddy local fauna.
The most noticeable difference between the two faunas

is the larger number of reptilian taxa in the Desertion

lasint local fauna. The predominance of lower vertebrates in

tihe Desertion Point local fauna may well have stronger
eeczologic than biostratigraphic implications. The abundant
meandering streams and minor incursions of Lake Gosiute
czlnaracteristic of the Laney Member of the Green River
.E?<:rmation and the lower Bridger Formation provided a variety

<:>1f environments conducive to a large, diverse, reptilian

iféaxuua.

Reptiles and amphibians are usually not considered in
ea-rly Tertiary biostratigraphic studies. While the
InElnlflmalian faunas of the Huerfano, Wind River, Bighorn, and
C335‘eeen River Basins have undergone almost continuous study

if<:”1? the last century, the lower vertebrates have rarely been

201

Cliscussed. Many localities throughout the Green River Basin

syuch as Desertion Point local fauna levels III and IV
(zontain abundant reptile remains and only a few mammals.
EStudies of both lower vertebrates and mammals will be

essential if the biostratigraphy of the Green River Basin is

to be completely understood. Most of the reptilian taxa

found within the study area are found through much of the

Palaeogene. Nevertheless, a single species of emydid,

absent from higher levels was collected from Desertion Point

local fauna level II. Eghmagegxs cf. g. cibollgngig noted

above may be indicative of pre-Bridger A deposition.

While the study area has yielded two distinct,

Zbiostratigraphically diagnostic assemblages, the diversity

(of both faunas is low compared to those of the Wind River

and Huerfano Basins. Additional field work needs to be done

t:<3 augment the sample of fossil vertebrates from the late

IEEarly and early Middle Eocene of the southwestern Green

Irztiver Basin. In addition, areas need to be sought where

't:3:ansitional faunas are preserved. Sedimentological

earxridence indicates that if these faunas are preserved, they

Should be sought along the margins of the basin, in regions

‘5711JLch escaped inundation by Eocene lake Gosiute.
The palaeobotany of the Wasatch, Bridger and Green

12¢i:\rer Formations needs to be studied. This information may

'E>3:W:rvide important information about the paleoecology of the

Gr‘een River Basin that is not available from other sources.

202

Iirvestigation of the stable isotope geochemistry of
czarbonate nodules and organic material within paleosols

sacross the boundary may shed light on paleoclimatic trends
ifrom the early to the middle Eocene. Taphonomic studies
‘would clarify many of the differences between the Little
iMuddy and Desertion Point local faunas. The collection of

fossil vertebrates derived from the various stratigraphic

units within the study area shows that preservation is

not only in the quality of individual

highly variable,
fossils, but also in taxonomic diversity between horizons,

the type of individual skeletal elements preserved, and in

the proportions of large, medium and small taxa present

Many of the differences between the two

(Zonneveld, 1994).
:faunas are based on taphonomic and paleoecologic factors

Isather than community succession.

From the study area to the northwest to Twin Buttes in
an

t:lne foothills of the Uinta Mountains to the southeast,

.51Z1most continuous stratigraphic sequence is now known in the

IE3nridger Basin temporally extending from the late early
lEScacene (Wa7) to the late middle Eocene (Br3). Magneto—
£3t:ratigraphic dating correlated with biostratigraphic

information would help calibrate North American

‘3fl112:onostratigraphy with European and Asian.
An impetus for future work in the area is that most

eeéadtrly Tertiary biostratigraphic studies ignore the potential
The fact that lower

JTDUUE>ortance of amphibians and reptiles.

203
vertebrates are much more common from the upper levels than

from the lower levels likely has stronger ecologic than

biostratigraphic implications. As noted above however,

there are differences in the reptilian taxa present at

di :fferent levels. Additional study of the lower vertebrates

is needed before their biostratigraphic significance can be

a s certained .

CONCLUSION
For the first time, the Wasatchian—Bridgerian Land

Mammal Age boundary has been identified within the vicinity
Of their type areas. This boundary is represented by
approximately 80 meters of stratigraphic section between two
distinct faunas within the Desertion Point-Little Muddy area
in the southwestern Bridger Basin, southwestern Wyoming. As
the Early Eocene drew to a close, Lake Gosiute expanded,
inundating most of the Green River Basin. This
transgression deposited the thick sequence of lacustrine
Sediments that comprises the Fontanelle Tongue of the Green
River Formation and separates the Desertion Point and Little
Muddy local faunas. As the waters receded, the valley was
repopulated with a fauna markedly different from that which
preceded the invasion of the lake. The biostratigraphic
Wasatchian—Bridgerian boundary does not coincide with the

lithostratigraphic Wasatch-Bridger boundary in southwestern

Wyoming (see Figure 18) , the type area of both of these

204
Land—Mammal Ages. The Wasatchian—Bridgerian boundary is
located approximately 200 meters below the base of the
Bridger formation within the study area.

Elements within the Little Muddy local fauna are
indicative of late Wasatchian deposition, particularly the
Lostcabinian index fossil Lambdotherium popoaggcig, but
also Meniscotherium chamense, Miacis latidens, and Hyopsogus
cf. _H_. worgmani. The time range of antius cf. Q.
frugivorgus is extended to include the Lostcabinian; that of
QM cf. Q. australotutus is confirmed as latest
Wasatchian. The Chronologic and geographic ranges of
Anflqrhxsig worgmani and m graxbulligug are extended
to include the Lostcabinian of the Green River Basin.

Elements from the Desertion Point local fauna are
indicative of the early Bridgerian. Desertion Point local
fauna level I through III are interpreted as earliest
Bridgerian (Gardnerbuttean) based on the co-occurrence of
W, W, and W. Desertion Point
local fauna levels IV and V are interpreted as late Early
Bridgerian based on the presence of Smilodggteg mcgrewi,

.Notharctug robinsoni, Washakius insignia, Onions cartgri,

and §cengpgggs along with Palaeggxons fontgngllis and
W modggtgs. The known time range of W

is extended to the early Bridgerian.

APPENDIX

205

APPENDIX

MEASURED STRATIGRAPHIC SECTIONS

Stratigraphic sections were measured using Jacob Staff,
1E3czrunton Compass, and metric tape-measure. Brief
<51<Ezscriptions of each section are supplied below. The
3E3crrecise location of each measured section is presented in
:E?L1.ate 1. A graphical correlation of all measured sections
xnrzi.thin the study area is supplied as Plate 2.

Grain size measurements are as follows:

phi Millimetres
mud 14.0 to 9.0 less than .004
silt 9.0 to 4.0 .004 to .063
va= 4.0 to 3.5 .063 to .094
va= 3.5 to 3.0 .094 to .125
fL= 3.0 to 2.5 .125 to .188
fU= 2.5 to 2.0 .188 to .250
= 2.0 to 1.5 .250 to .375
mu: 1.5 to 1.0 .375 to .500
cL= 1.0 to 0.5 .500 to .750
cU= 0.5 to 0.0 .750 to 1.000
ch= 0.0 to -0.5 1.000 to 1.500
ch= —0.5 to -1.0 1.500 to 2.000

Measured Section 1, Camp Section
Mulkay Springs Quadrangle, T. 19 N., R. 115 W., Section
23,~SW1/4, NW1/4. The west face of the third ridge
south of the Desertion Point escarpment. From the base
of the escarpment to the main break in slope. Through
fossil localities BB068 and BB069.

Ll£;;Q Thickness Description
(:lraven buried sequence.
c:Ili‘eek. 1.10m Siltstone, gray.

EBCi 0.80m Litharenite, gray, coarsens up from.

mL to mU, moderate sorting,
Laney subrounded .
Member , l . 50m Muds tone , gray, silty .
0.45m Sublitharenite, gray, fL, moderate

G3|:‘een sorting , subrounded .

jsver 0.54m Mudstone, light gray, trace silt.

(Drnation 0.96m Siltstone, yellowish-gray, sandy,

206

weathers to brown.

0.50m Lignitic mudstone, brown, abundant
ash and organic debris, contains
lenses of selenite and gypsum,
poorly preserved plant debris, and
abundant sulphur seams, weathers

 

brown.

1.65m Claystone, yellowish gray, weathers
yellow.

0.70m Mudstone, light gray, silty.

1.65m Sublitharenite, fL, subrounded,
moderate sorting, weathers rusty
red.

0.20m Mudstone, gray, sandy.

0.28m Sublitharenite, gray, fU,

subrounded, moderate sorting,
weathers rusty red.

2.04m Mudstone, whitish gray, trace silt,
darkens in colour downwards to a
greenish gray, rx HCL.

0.68m Mudstone, pinkish gray, coarsens
down to sandy at base, does not
react with HCL.

TCIIpper 0.39m Sublitharenite, gray, mL,
Member subrounded, moderate sorting, rx
HCL, weathers rusty red.
Wasatch 0.20m Mudstone, olive green, some silt.
jErormation 0.79m Mudstone, tan brown, some silt,

grades up to a mottled green and
brown, rx HCL.
0.40+ Mudstone, olive green, some silt,
somewhat mottled, rx HCL, iron
stains and gypsum in fractures.
buried sequence

207

Measured Section 2, New Crocodilian Section
Mulkay Springs Quadrangle, T. 19 N., R. 115 W., Section
23, SWl/4, SWl/4. Up the axis of the prominent ridge
due east of BB013W. From the valley floor to the
boundary lignite. Through fossil localities BB013 and

 

BB036.
tifiriit Measurement Description
top of section
(Ixzraven 0.20m Mudstone, white, hard.
(Ziacheek 0.10m Lignitic Mudstone, gray—brown,
Bed weathers dark brown, abundant plant
debris. high ash content.
1.35m Mudstone, dark gray, some silt,
biotite flakes abundant.
0.70m Sublitharenite, gray to rusty red,
fines upwards from mL/fU to va,
moderately sorted, subrounded.
Upper 0.37m Mudstone, gray, silty, sandy, fines
Member, up to a silty mudstone.
0.42m Sublitharenite, gray, subrounded,
ERIEisatch well sorted, fines upwards to a
JF’CDInation sandy siltstone, carbonized root
traces at base
0.52m Siltstone, dark gray, dark gray

mudclasts common, random poorly
preserved root or leaf impressions,
top 2cm organic rich.

0.54m Mudstone, light gray, silty,
mottled in places, coarsens up from
a mudstone, trace silt, mudclasts
abundant.

0.50m Mudstone, light gray-brown,
abundant purple and red flecks
(oxidation residues) abundant dark
gray mudclasts.

0.35m Siltstone, gray, sandy, abundant
lithic fragments.

0.59m Litharenite, gray, mL, moderately
sorted, subrounded, weathers rust
red.

0.59m Mudstone, gray, silty.

0.45m Mudstone, light gray, trace silt.

0.10m Mudstone, tan-gray.

0.17m Mudstone, gray-brown, abundant
concentric carbonate nodules.

0.10m Siltstone, gray, muddy, mudclasts

abundant, fish bits and brown
pellets as above also present.

0.71m Mudstone, gray, silty, pellets as
above, coarsens upwards slightly,
mudclasts throughout.

1:1];xper
Jyleenmber,

Wasatch
F ormation

CO

OO

0

.70m

.35m

.18m

.40m

.26m

.34m

.28m

.86m

.10m

.57m

.20m

.62m
.24m

.21m
.04m

.02m
.06m

.06m

208

Sublitharenite, fL, subrounded,
poorly sorted, mudclasts and red
chert shards common.

Mudstone, greenish gray, trace
silt, abundant mudclasts and
biotite flakes, pink/purple
mottling 15cm above base.
Siltstone, light green-gray, lithic
fragments and mudclasts common.
Mudstone, gray, trace silt,
mudclasts common throughout,
although less so near top.
Mudstone, maroon, gray/green
mottling, trace silt, mudclasts
common.

Mudstone, tan-gray, silty,
mudclasts common.

Mudstone, pink, some silt at base,
less at top, tiny gray mudclasts
common throughout.

tan/gray mudstone, some silt,
laminated, mudclasts abundant,
lithic fragments present although
not common, mudclasts larger and
pinker towards base.
Sublitharenite, mL to fU,
subrounded, well sorted, weathers
red, soft sedimentary deformation
at base, this unit interfingers and
probes into the lower unit,
Mudstone, mottled green, gray,
brown, and pink, silty at base,
fines upwards, very abundant
mudclasts, bedded, rx HCL, pink
mudstone lense 0.20m from base.
Mudstone, purple, fines upwards,
base is silty and mottled with
green.

Mudstone, gray, sandy.
Litharenite, gray, va to cU,
extremely variable in grain size,
shape and sorting, finer grained
towards middle of unit, cross-
bedded.

Mudstone, light gray, silty.
Sublitherenite, gray poorly sorted,
subangular.

Mudstone, gray.

Sublitharenite, poorly sorted,
subangular to subrounded.
Mudstone, gray.

ISHQper
Ixnember,

Wasatch
F ormation

OO

.09m

.31m
.40m

.15m

.01m

209

Mudstone, mottled red, gray, green,
and maroon.

Mudstone, gray.

Siltstone, gray, sandy, wedge
shaped cross-bedding.

Mudstone, alternating red and gray
lenses, some silt.

Mudstone, gray, trace silt, grades
up into a sandier layer with a few
mudclasts (gray), and into a
reworked mess of sandier material
surrounding large rip—up clasts,
sand is angular and poorly sorted,
a zone of red mudclasts 0.20m from
top of unit, above this the
mudclasts decrease in size and
number, and the unit gets muddier
and less sandy, Crocodile and
turtle specimen found in this
layer.

210

Measured Section 3, Lost Butte Section
Mulkay Springs Quadrangle, T. 19 N., R. 115 W., Section
22, SE1/4, SE1/4. From the valley floor to the top of
the small butte 250m west of the Desertion Point
Escarpment. Through fossil locality BBOl3W.

Unit Thickness Description
top of Butte
0.58m Mudstone, gray, trace silt, trace
sand, fines upwards slightly.
Craven 1.75m Litharenite, gray-brown, mL,
Creek subangular to subrounded, poorly
Bed, sorted, silty near top,
crossbedded, mudclasts present.
Laney 0.42m Mudstone, gray, yellowish near top,
Member,- trace silt.
0.90m Mudstone, brown, sandy, silty,
Green fines upwards, gray mudclasts
River abundant, especially at top and
Formation base of unit, bedded, broken bits

of fossil fish and reptile
abundant, ooids present.

0.06m Micrite, yellow—gray, sandy.

0.25m Sublitharenite, white to gray,
moderate sorting, fU, subangular to
subrounded grains, weathers rust
red.

0.60m Siltstone, gray.

0.98m Mudstone, gray, trace silt.

0.20m Sublitharenite, gray, mL, moderate

sorting, subrounded, crossbedded.
Base of butte.

211

Measured Section 4, Microsyops Skull Section
Mulkay Spring Quadrangle, R. 115 W., T. 19 N. Section
26, NEl/4, NW1/4. The ridge at the centre of the
valley due north of fossil locality BB076. From the
base of the valley to the last break in slope below the
top of the escarpment. Through fossil localities BB013

and BB036.
Unit Thickness Description
Top of butte.
0.35m Micrite, light yellow,some sandy
regions, possible insect fossils.
0.04m Ash layer, white.
0.81m Mudstone, interbedded gray and
gray—green.
1.13m Mudstone, gray.
0.70m Mudstone white.
0.20m Mudstone, olive green, greyer
towards top.
0.10m Micrite, white to yellow, sand and
biotite laminae (possibly ash)
common, abundant gar and amia
scales.
Craven 0.48m Siltstone, gray, sandy, fossils
Creek (mostly fish) common as are ooliths
Bed, and mudclasts.
0.22m Micrite, light yellow, oolitic.
Laney 0.25m Litharenite, poorly sorted, silty,
Member, mudclasts and vertebrate fossils
(mostly fish bits) common.
Green 0.20m Micrite, yellow-white, sand and
River mudclasts common.
Formation 0.10m Sublitharenite, gray, mL, moderate
sorting, subrounded.
0.70m Mudstone, dark brown, organic rich,

10cm from base thin orange layer
with abundant gypsum,

0.68m Litharenite, gray, mL to cU,
subangular to angular, poorly
sorted, abundant mudclasts,

crossbedded.
1.60m buried sequence
0.20m Litharenite, gray, mL to cU,

subangular to angular, poorly
sorted, abundant mudclasts,

crossbedded.
0.29m buried sequence
1.45m Litharenite, gray, mL to cU,

subangular to angular, poorly
sorted, abundant mudclasts,
crossbedded.

Craven
Creek
Bed,

Laney
Member,

Green
River
Formation

l—‘O

.51m

.22m

.04m

.04m

.35m

.50m

.45m

.08m
.33m

.57m

.22m

.32m

.75m

.64m

.34m

.66m

.10m
.94m

.70m

212

Mudstone, gray, abundant organic
rich lenses.

Litharenite, light gray, mU to ch,
angular to subrounded, poorly
sorted, abundant mudclasts,
weathers to rust red, cross—bedded.
Mudstone, gray, some silt, abundant
gray mudclasts.

Litharenite, gray, fU to mL, poor
to moderate sorting, subrounded,
weathers rust red.

Mudstone, gray-tan, some silt, gray
mudclasts abundant near base, rust
coloured lenses common.

buried sequence

Mudstone, gray, mudclasts common,
organic rich.

Mudstone, gray, sandy.

Mudstone, gray, sandy at base,
mudclasts common near top, also
some sand clasts present, both
gastropods and bivalves common.
Siltstone, gray, sandy, coarsens up
to a litharenite, gray, fL,
moderate sorting, subrounded.
Mudstone, gray, some sand, some
silt, mudclasts common, coarsens
upwards slightly.

Siltstone, gray—tan, sandy, fines
upwards slightly.

Sublitharenite, mL, subrounded,
moderately sorted, cross-bedded.
Mudstone, gray, sandy, gray
mudclasts abundant, mudclasts more
abundant base, bivalve pelecypods
present but poorly preserved.
Mudstone, gray, silty, sandy,
biotite flakes and mudclasts
abundant, sandier towards top.
Mudstone, gray, siltier towards
top.

Mudstone, white, calcareous.
Mudstone, light gray, some sand,
some silt, mudclasts present, more
abundant towards bottom, fines up
slightly, abundant fish bits.
Mudstone, green-gray, abundant
large, elongate, horizontal
mudclasts, abundant organic debris,
and abundant rounded, elongate
brownish pellet-like inclusions,

 

 

Craven
Creek
Bed,

Laney
Member,

Green
River
Formation

.33m
.10m

.44m

.75m

.65m

.53m

.03m

.07m

.22m

.18m

.17m

.88m

.65m

.56m

213

probably ooliths near top, fish
bits also common.

Micrite, yellow, stromatolitic.
Litharenite, dark gray, moderate
sorting, subrounded.

Mudstone, light gray, contains
abundant fish bits.

Siltstone, gray, sandy, sand lenses
and fish debris common.

Mudstone, white, abundant fish
bits.

Mudstone, gray—tan, sand and silt
lenses, fish bits common.
Sublitharenite, fL, poorly sorted,
rounded.

Micrite, stromatolite pods thick in
places.

Mudstone, gray, some silt, fish
debris common.

Mudstone, white, hard.

Lignitic mudstone, dark brown to
gray and yellow, abundant plant
debris, high ash content.

Mudstone, dark gray, some silt,
abundant biotite flakes.
Litharenite, gray, fL to mL, poorly
sorted, abundant greenish
mudclasts, vertebrate fossils very
abundant, fish, turtle,
crocodilian, cross-bedded.
Siltstone, gray, muddy, top 25cm
has abundant sandy regions, sandier
and less muddy towards the top.

Base of butte.

214

Measured Section 5, Desertion Point Upper Section
Mulkay Springs Quadrangle, T. 19 N., R. 115 W. Section
26, SE1/4, SW 1/4. From the top to the base of the
escarpment at the southern end of Desertion Point.
Through fossil localities BB075 and BB012.

Unit Thickness Qpppgippipp
Top of butte.
0.30m Micrite, white-gray, trace sand. la
5.77m Mudstone, gray, silty. ;“
1.05m Sublitharenite, gray, mL, well— -
sorted, rounded.
0.40m Mudstone, gray, silty.
0.85m Sublitharenite, gray, mL, well
sorted, rounded.
0.21m Mudstone, gray, some silt.
2.46m Sublitharenite, gray, mL, well
sorted, rounded.
Craven 1.48m Mudstone, gray-brown, silty, some
Creek sand.
Bed, 0.90m Mudstone, gray, some silt.
0.10m Micrite, light gray, weathers rust
Laney red.
Member, 1.10m Lignitic mudstone, brown and
yellow, black, broken up bits of
Green carbonized plant material common,
River selenite and gypsum in fractures.
Formation 0.80m Mudstone, gray.
0.56m Sublitharenite, gray, mL, well
sorted, rounded.
0.85m Mudstone, gray-brown, some silt.
0.79m Sublitharenite, gray, fU, well—
sorted, rounded.
3.45m buried sequence
1.15m Silty mudstone, gray-green.
2.60m Buried sequence.
3.95m Litharenite, sorting, angularity,

and grain size varies widely
throughout the unit, cross-bedded.

0.27m Mudstone, gray—green, silty,
biotite flakes common.

0.40m Mudstone, white, some silt, mottled
appearance, mud clasts present.

0.30m Mudstone, green-gray, silty,

biotite flecks abundant.
Buried sequence

Measured Section 6 ,

215

Desertion Point Lower Section

Mulkay Springs Quadrangle, T. 19 N., R. 115 W. Section

26,

SE1/4,

From the break in slope to the base

of the escarpment at the northern end of Desertion

 

Point. Through fossil locality BB070.
Unit Thickness Description
Buried sequence
0.80m Mudstone, gray, mottled, mudclasts,
and fish scales common.
1.45m Mudstone, yellow-gray, silty.
0.65m Sublitharenite, gray, mL, well
sorted, rounded.
0.56m Mudstone, gray-green, silty,
biotite flakes common.
Craven 0.78m Siltstone, gray, sandy. biotite
Creek flakes common.
Bed, 1 01m Mudstone, yellow—gray, trace silt,
yellow concretions and biotite
Laney flakes common.
Member, 0.80m Siltstone, gray.
0.20m Litharenite, gray, mU, poorly
Green sorted, subrounded.
River 0.50m Siltstone, gray, sandy.
Formation 1.75m Mudstone, gray, some silt towards
the top.
0.40m Sublitharenite, gray, mL, well-
sorted, subrounded.
1.45m Mudstone, white-gray, silty, Ania
scales, and bivalves common.
1.35m Sublitharenite, gray, mU, well—
sorted, subrounded, fossiliferous,
teleost bones, bivalve molluscs.
0.80m Siltstone, gray, some sand, grades
up into a siltv mudstoneLL.
Upper 0.20m Siltstone, gray-green.
Member, buried sequence.
Wasatch

Formation

Me asured Sec tion 7,

216

Dead Antelope Draw.

Mulkay Springs Quadrangle, T. 18 N., R. 115 W. Section

2, NEl/4, NW1/4.

From the base to the top of the

prominent escarpment. Through Fossil Locality BBO77.

Unit

Craven
Creek
Bed,

Laney
Member,

Green
River
Formation

Thickness
.10m

.92m
.15m

.25m

.27m

.10m

.07
.28m

.21m

.42m
.18m

.78m

.14m

.58m

.18m

.73m

.10m

Description

buried sequence

Lignitic mudstone, brown, abundant
plant material.

Buried sequence

Mudstone, gray, silty, lignitic
layer 0.75m from top.
Litharenite, gray, fL, poorly
sorted, contains large lithic
fragments, subrounded to
subangular.

Mudstone, gray-brown, some silt,
abundant organic material towards
top.

Mudstone, gray-green, weathers into
hard white chips.

Mudstone, white-gray, some silt.
Mudstone, yellow-gray, organic
rich, silty, sand lenses near the
bottom, abundant mudclasts,
abundant fossils.

Siltstone, gray, coarsens upwards
slightly.

Mudstone, gray, some silt.
Tilloid, light brown, grains are
well-rounded, poor sorting,
possibly mud ooids, weathers to
orange.

Mudstone, gray, some silt,
sandstone lense 0.20m from base,
0.02m thick.

Sublitharenite, gray, fU, well-
sorted, subrounded, fossils of
lower vertebrates present.
Mudstone, gray, some silt, fines
upwards slightly, sand lenses near
base.

Sublitharenite, gray, silty, fU,
poorly sorted, subrounded,
fossiliferous (fish bits).
Mudstone, mottled gray, slightly
silty towards top, sand lense 0.20m
from base, lower vertebrate
fossils.

Litharenite, fU, poorly sorted,
subrounded.

I1

 

Craven
Creek
Bed,

Laney
Member,

Green
River
Formation

Upper
Member,

Wasatch
Formation

.01m

.21m

.40m

.96m

.16m

.32m

.04m

.93m

217

Siltstone, gray, interbedded silty
and muddy layers, fossils abundant,
contains crocodilians, turtles,
fish, rarely mammals.
Sublitharenite, fU, moderate
sorting, subrounded, weathers rust
red.

Mudstone, white-gray, abundant
biotite flakes, no fossils observed
in most of the unit, the top 0.08m
of the unit increasingly silty, a
hard muddy layer totally devoid of
silt 0.60m from top, above this is
a 0.05m thick pinkish mudstone
layer that contains abundant fish
bits.

Mudstone, gray, slightly silty
towards top, abundant mudclasts,
bivalve mollusc at base.

Mudstone, tan, organic rich,
laminated, gypsum layer at base,
grades into above.

Mudstone, gray, gypsum layer at
base.

Lignitic mudstone, gray—brown,
silty, organic rich, gastropods
present.

Siltstone, gray, sandy, fines up to
silty mudstone, mudclasts common,
organic bits also common especially
near the top, worm burrows common
at base.

Buried sequence

218

Liesasured Section 8, The Lost Locality.
Mulkay Springs Quadrangle, T. 19 N., R. 115 W., Section
22, NEl/4, NW1/4, From the base of the wash to the top
of the hill. Through fossil locality BB103.

tJnit Thickness Qpppgippigp
Buried sequence
0.40m Mudstone, gray, trace silt.
0.91m Mudstone, light purple, tiny gray
mudclasts present.
0.14m Mudstone, gray.
0.75m Mudstone, gray mottled with pink,
red mudclasts common.
0.39m Mudstone, mottled gray, purple,
rust, maroon, trace silt.
0.35m Mudstone, gray, greenish towards
top, some silt.
0.89m Siltstone, gray.
0.14m Mudstone, gray to pinkish gray
trace silt, abundant gray
mudclasts.
0.02m Sublitharenite, gray, mL, moderate
sorting, subrounded.
0.16m Micrite, gray, abundant mudclasts,
sandy towards top.
“Upper 0.36m Mudstone, gray, some silt, abundant
IMember, mudclasts.
0.04m Mudstone, brown, mudclasts
Wasatch abundant .
Formation 0.07m Mudstone, gray, trace silt,
abundant maroon mudclasts.
0.14m Micrite, gray, contains mudclasts.
0.59m Mudstone, gray, some silt, mottled

reddish at base, abundant elongate
horizontal mudclasts at base,
darkens towards top, purple and red
mudclasts at top.

0.22m Mudstone, light reddish mottled
purplish brown, trace silt, tiny
brown mudclasts present.

0.30m Mudstone, light brown, silty.

0.16m Sublitharenite, light gray, fL,
subrounded, moderate sorting.

0.22m Mudstone, light brown, trace silt,
darker brown and no silt at top.

0.58m Mudstone, purple-brown, trace silt,

maroon, gray and brown mudclasts,
darker at top, mudclasts less
abundant near top.
0.42m Mudstone, dark gray-green, trace
silt, lightens upwards.
base of wash.

219

bdeeasured Section 9, Wasatch Butte Section A
Mulkay Spring Quadrangle, T. 18 N., R. 115 W., Section
9, SWl/4, NEl/4. From base to top of Hill 6547, 600
meters north of the Little Muddy Creek. Through Fossil
Locality BB097.

 

'LInit Thickness Description
top of butte
0.40m Mudstone, gray, silty, pink near
the top.
0.75m Mudstone, pink, some silt, greyer
at base.
0.17m Mudstone, gray, silty.
0.15m Mudstone, pink, trace silt.
0.21m Mudstone, gray, trace silt.
2.09m Mudstone, orange-pink.
0.12m Mudstone, gray, some silt.
0.35m Mudstone, red.
0.15m Siltstone, gray.
0.18m Mudstone, red, trace silt.
0.35m Siltstone, gray, coarsens up to
gray fL sandstone, poorly sorted,
subangular.
0.67m Mudstone, purple, rust red near
top, trace silt.
Upper 1.11m Mudstone, light brown—orange, trace
IMember, silt, gray mottling 0.30m from
base.
‘Wasatch 0.96m Sublitharenite, gray, mU to fU
Formation subrounded, fines upwards, moderate
sorting.
0.96m Mudstone, orange brown to pink,
coarsens up to silty mudstone, top
3cm gray.
0.40m Mudstone, brown, bottom 0.10m dark
brown, top 0.10m light brown.
0.15m Mudstone, purple-gray.
0.61m Mudstone, purple, darkens upwards,
top 0.10m mottled gray.
3.76m Mudstone, white gray, silty, fines
up to a mudstone, trace silt.
0.74m Mudstone, white—gray, trace silt.
0.35m Mudstone, purple, silty, abundant
biotite flakes.
0.72m Sublitharenite, gray, fU, moderate

sorting, top 0.02m silty, abundant
red mudclasts, worm burrows and
bioturbation common.

0.59m Mudstone, pink, red mudclasts
common towards base, purple
mudclasts and sand filled worm
burrows common throughout.

tIIDper
I"hamber,

VVasatch
Formation

OO

C

00000

.18m

.71m

.20m

.10m

.51m

.63m
.72m

.22m
.14m
.39m

.21m

.24m

.16m

.03m
.16m
.20m
.17m
.03m

0.34m

NO

.04m
.15m

.65m

220

Litharenite, gray, fL, poorly
sorted, subangular to subrounded,
red mudclasts also abundant.
Mudstone, purple-red, top 0.15m
coarsens upward slightly, red
mudclasts increase in abundance
upwards.

Mudstone, gray,silty, fines upwards
slightly.

Sublitharenite, gray, fU, poorly
sorted, angular.

Mudstone, red, trace silt, coarsens
upwards slightly, no silt at top,
trace biotite.

Mudstone, gray, silty.

Mudstone, purple, some silt,
biotite flakes present, contains
abundant red mudclasts,
increasingly mottled gray towards
the top.

Sublitharenite, gray, mL, well-
sorted, subrounded.

Mudstone, purple-red.

Mudstone green—gray, biotite
present, mottled purple/red towards
top.

Mudstone, purple-red, trace silt,
increasingly mottled rust red—gray
towards top, slight coarsening
upwards.

Mudstone, gray, some silt, abundant
biotite flakes, possibly high ash
content.

Mudstone, red, darkens upwards to
maroon.

Mudstone, red, trace silt.
Mudstone, purple-red, silty.
Mudstone, maroon to red, some silt.
Mudstone, red, silty, sandy.
Mudstone, mottled rust red, gray,
green, and purple.

Mudstone, mottled green and blue.
Mudstone, red, silty.
Sublitharenite, gray, mL,
subrounded, medium sorting.
Mudstone, mottled purple, maroon,
rust red, grey- rimmed yellow,
trace silt, rx HCL variable,
fossils, crocodilian and turtle.

Wk

UIDIDer
MEernber,

Wasatch
Formation

0.24m

1.22m

221

Sublitharenite, gray, fU, well
rounded, well—sorted.

Mudstone, mottled yellow, purple,
gray, maroon, rust red, some silt

near the top.

Base of Butte.

222

jMEaaasured Section 10, Wasatch Butte Section B

[ha:it:

Upper
Idember,
Wasatch
Formation

Mulkay Springs Quadrangle, T. 18 N., R. 115 W.,
from Section 4, SWl/4, SE1/4 to Section 9, NW1/4,
NE1/4. From the top to the bottom of the
prominent ridge at the centre of Wasatch Butte.

Thickness Description
Buried sequence

0.60m Sublitharenite, mL, poorly sorted,
subangular.

1.40m Mudstone, greenish gray, trace
silt, trace sand.

0.80m Mudstone, gray, fines upwards from
trace silt at base, greenish near
top.

2.27m Caliche, white, composed primarily
of calcareous nodules.

0.76m Mudstone, purple, trace silt.

0.31m Mudstone, red, some silt.

0.15m Mudstone, gray-green, sandy.

0.34m Sublitharenite, fL, moderately
sorted, subrounded.

0.10m Siltstone, purple, sandy, mottled
gray at base.

0.71m Sublitharenite, fL, moderately
sorted, subrounded.

0.17m Mudstone, red.

0.22m Mudstone, purple—gray, trace silt.

0.24m Sublitharenite, gray, mL, moderate
sorting, subangular grains.

0.20m Mudstone, purple, silty.

0.27m Siltstone, sandy, greenish gray.

0.53m Mudstone, brownish pink, some silt.

0.30m Mudstone, light purple, silty at
base, trace silt at top.

0.38m Sublitharenite, mL, poorly sorted,
subangular, abundant mudclasts.

0.18m Siltstone, gray, coarsens upwards
to a sandy siltstone.

0.08m Mudstone, pink, trace silt,

coarsens upwards to a silty
mudstone, top few centimetres are
mottled.

1.20m Siltstone, mottled pink and gray,
biotite common, some mudclasts near
bottom, fines and greys upwards to
a gray silty mudstone.

0.29m Mudstone, reddish purple, silty.

1.68m Siltstone, sandy, gray, top pink.

0.69m Siltstone, gray, muddy, coarsens up
into above unit.

0.15m Mudstone, gray-green, trace silt.

Buried sequence

 

223

Measured Section 11, Wasatch Butte Section C.
Mulkay Spring Quadrangle, T.18 N. R. 115 W., Section 4,
SE1/4, SEl/4. From top to base of escarpment at the
northern end of Wasatch Butte.

Urisit: Thickness Description
Top of Butte.
0.81m mudstone, gray, some sand.
0.84m mudstone, rust red, some sand.
0.81m litharenite, gray, mL to mU, poorly
sorted, subangular, abundant.
Upper 0.25m mudstone, rust red, sandy.
bkaxfikaer, 0 25m mudstone, gray, coarsens upwards
rapidly to a very sandy mudstone,
Wasatch to a mL sandstone, moderate to poor
‘Fontrnation sorting, subrounded to subangular.
1.00m mudstone, red, some silt, tiny gray

mudclasts, some mottling, lense of
greenish gray mudstone with
abundant mica at 1.41m.

0.38m mudstone, grey, sandy, purple
mudclasts abundant near bottom,
fines up to a mudstone, some silt.

0.14m mudstone, purplish brown, sandy.

0.10m mudstone, gray, sandy, purple
mudclasts, and purplish mottling
throughout.

0.36m mudstone, purple-gray, sandy, many

of the sand grains are dark, some
gray mudclasts.
Buried sequence

224

Measured Section 12, Wasatch Butte Section D
Mulkay Spring Quadrangle, T. 18 N., R. 115 W., Section
4, SEl/4, SE1/4. From base to top of ridge due north
of Wasatch Butte Section C.

Urrj.t; Thickness Description
Buried sequence
0.04m Mudstone, purple.
0.44m Mudstone, gray, some regions
mottled pink, purple, and red.
0.22m Mudstone, mottled purple, maroon,
pink, weathers purple.
0.79m Sublitharenite, gray, fU to mL,
Upper moderately sorted, subangular,
Mernber, fines up to a siltstone 0.20m from
base, and a mudstone 0.45m from
Wasatch base. -
chrtnation 1.51m Mudstone, gray, some silt, red and
brown lenses.
0.42m Mudstone, gray, silty, coarsens up
to a gray siltstone.
0.41m Mudstone, pink, trace silt.
0.75m Siltstone, gray, sandy, fines up to

a gray silty mudstone, some sand,
mudclasts brown near bottom, gray
near the top.
1.15m Sublitharenite, gray, fU, well-
sorted, subrounded.
Buried sequence

225

LMEeéasured Section 13, Cumberland Gap Section.
Cumberland Gap Quadrangle, T. 19 N., R. 116 W., Section
34, SE 1/4, NE 1/4. From the base to the top of the
tall escarpment north of Little Muddy Creek, and east
of Ziller Ranch. Through Fossil Locality BB118.

 

Urith: Thickness Description
Top of Butte

3.78m Micrite, tan, abundant ostrocods
Forthzenelle and gastropods of the genus
Tongue, Goniobasis, thick bedding towards

top of unit, thinner bedding with

Green abundant light gray mudstone lenses
Ri\r<an: towards base, mudstones contain gar
Fonrrrmtion scales and fish spines.

4.10m Mudstone, green—gray, silty, grades

into a highly calcareous mudstone
at base, laminated.

La Barge 0.15m Micrite, tan.
Member, 1.60m Mudstone, brown, gray and maroon
lenses, laminated.
Wasatch 0.98m Sublitharenite, gray, ml to fU.
FWormation 0.68m Mudstone, red brown, trace silt.
1.25m Sublitharenite, gray, red and gray

mudclasts and mudstone lenses
common throughout, fines upward
from mL to va, weathers red.

7.22m Mudstone, variegated gray, red,
purple, gray-green, trace silt.

2.33m Sublitharenite,-gray, mL to mU,
biotite flakes abundant.

0.55m Mudstone, mottled red and gray,
abundant biotite and rust red
inclusions.

0.44m Sublitharenite, silty, ml, coarsens
upwards.

0.30m Mudstone, red, silty, trace sand.

0.30m Mudstone, gray, silty, trace sand.

0.80m Mudstone, red with yellow and gray
mottling, silty, trace sand.

1.22m Sublitharenite, gray, mL.

0.67m Mudstone, mottled yellow red and
gray, silty at base.

0.63m Siltstone, gray, some yellow and
pink mottling.

0.15m Mudstone, red, trace silt.

0.10m Litharenite, gray, mL to mU.

1.08m Mudstone, gray, silty, abundant
biotite flakes.

0.90m Litharenite, gray, cL.

0.40m Mudstone, gray-green, trace silt.

0.10m Mudstone, purple, trace silt.

La. IBarge
lflemnfloer,

Wasatch
Formation

.18m

.90m

.24m
.64m

.42m

.34m

.15m

.35m

.30m

.40m

.35m

.40m

.95m

.00m

.50m
.25m

.20m
.51m
.50m
.50m
.49m

.28m

.21m

.98m
.47m
.63m

226

Mudstone, mottled red and yellow,
trace silt.

Siltstone, gray, sandy, biotite
present, coarsens upwards to
sublitharenite, fL.

Mudstone, red, silty.
Sublitharenite, gray, silty, mL,
biotite flakes and red mudclasts
abundant towards top.

Mudstone, red, mottled gray in
places, thin gray interbeds
throughout.

Litharenite, gray, mL to mU.
Mudstone, red, with white, gray,
and mottled purple lenses.
Mudstone, gray, silty, sandy,
coarser at base, biotite flakes and
red mudclasts common.

Mudstone, red, trace silt.
Siltstone, gray, sandy, gray
mudclasts present throughout.
Mudstone, red, trace silt, siltier
at base.

Mudstone, gray, trace silt, red
mottling in places.
Sublitharenite, gray, fU to mL,
weathers red.

Mudstone, variegated, red, purple,
yellow, and gray, silty, hard,
fractured.

Sublitharenite, gray, fU.
Mudstone, variegated, primarily
red, also purple, yellow, and gray,
silty, hard, fractured.
Sublitharenite, gray, fU.
Siltstone, mottled purple and
yellow, sandy, fines upwards.
Sublitharenite, gray, fL, thin red
mudstone interbeds.

Mudstone, red, some sand, greyer
and sandier towards top.
Siltstone, mottled red and yellow
gray, less mottling towards top.
Litharenite, dark gray to yellow,
angular rock fragments, abundant
red mudclasts, and red and yellow
mudstone interbeds.

Mudstone, red and gray lenses,
trace sand.

Siltstone, yellow-gray, some sand.
Mudstone, yellow-gray.

Mudstone, mottled red and gray.

La Barge
Member,

Wasatch
Formation

HO

0

.90m

.28m

.44m
.82m

.30m
.50m

.20m

1.30m

COP-’0

.24m
.24m
.21m
.55m

227

Mudstone, yellow with red and gray
mottling.

Mudstone, gray, mammalian caudal
vertebra, insectivore astragalus,
gar vertebra and scales recovered
from unit.

Mudstone, red.

Siltstone, gray, trace sand, some
mud.

Mudstone, red, trace silt.
Siltstone, gray at top blends to
red at base, trace sand, trace mud.
Mudstone, red, silty.

Siltstone, reddish gray, sandy,
abundant biotite flakes.

Mudstone, red, some silt.
Litharenite, gray, mU.

Mudstone, gray, trace silt.
Mudstone, red mottled with gray and
yellow, trace silt.

Base of butte

 

228

Measured Section 14, Kizmi Butte Section.
Mulkay Springs Quadrangle, T. 18 N., R. 115 W., Section
8, NE 1/4, SE 1/4. From base to top of Kizmi Butte.

U_nit 1h_i.c_:_l_<_n_e_s_§ Dam
Top of butte
0.25m Micrite, concentric algal pods
0.02m to 0.30m in diameter.
1.01m Siltstone, gray, some sand. “a
0.49m Mudstone, red, silty. .‘
0.40m Micrite, concentric algal pods
0.02m to 0.30m in diameter.
0.30m Mudstone, gray, silty, some sand.
0.74m Mudstone, purple-red, silty, some
sand. '
1.35m Litharenite, gray, mL, subrounded, 1
moderate sorting, thickness |
variable. I
3.00m Mudstone, red, some silt.
1.10m Litharenite, gray, mL, subrounded, ‘

moderate sorting, thickness
somewhat variable.

0.20m Mudstone, red, some silt.
0.31m Sparite, white, no fossils
apparent.
Upper 0.05m Mudstone, red, trace silt.
Member, 1.08m Litharenite, gray, mL to fU,
subrounded, moderate sorting.
Wasatch 0.40m Mudstone, red, trace silt.
Formation 0.30m Litharenite, gray, mL to fU,
subrounded, moderate sorting.
1.45m Mudstone, red, trace silt, trace
sand.
0.15m Siltstone, gray, trace sand.
0.40m Mudstone, red, trace silt, trace
sand.
0.32m Litharenite, gray, fL to fU,
subrounded, moderate sorting.
0.23m Siltstone, gray, trace sand.
0.20m Sparite, light gray, no fossils
apparent.
0.65m Mudstone, red, trace silt, trace
sand.
0.60m Litharenite, gray, fL, subrounded,
moderate sorting.
0.70m Mudstone, light gray, highly
calcareous, trace silt.
0.60m Mudstone, red with white bands,
some silt.
0.10m Litharenite, gray, fL, subrounded,

moderate sorting.
Upper 12.48m Mudstone, red, thin white lenses in

Member,

Wasatch
Formation

New Fork
Tongue,

Wasatch
Formation

.18m

.16m
.04m

.38m
.50m

229

places, some silt.
Sparite, white, no fossils
apparent.
Mudstone, red, some silt.
Litharenite, gray, fL to fU,
subrounded, moderate sorting.
Mudstone, red, some silt.
Litharenite, gray, mU to cL, poorly
sorted, cross—bedded, unit
thickness variable.

Base of butte.

 

230

Measured Section 15, Big Dutch Butte Section.

Mulkay Springs Quadrangle, T. 18 N., R. 115 W., Section 5,
SW 1/4, SE 1/4, SE l/4 to Section 8, NW 1/4, NE 1/4, NE 1/4.
From base to top of Big Dutch Butte.

Unit Thickness Description
Top of butte -
5.00m Litharenite, gray, mU, moderate

sorting, subrounded to subangular,
lenticular cross-bedding, grain
size sorting, and thickness of unit
highly variable.

0.50m Lithic conglomerate, poorly sorted,
subangular to rounded, abundant
yellowish mudclasts, reptile bones
including turtle carapace fragments
and crocodile limb elements common
in places.

Upper 4.55m Litharenite, gray, mL to cU,
Member, moderately sorted, subrounded,
0.01m to 0.10m conglomeratic lenses
Wasatch throughout, lenticular cross
Formation bedding.
0.95m Mudclast conglomerate, gray, cU,

grain size and sorting variable,
mudclasts parallel to, bedding.

1.84m Mudstone, red, mottled gray and tan
in places, silty, some sand.

0.40m Litharenite, gray, mL, subrounded,
moderate sorting.

4.23m mudstone, red, some silt.

0.41m Litharenite, gray, mL, subrounded,
moderate sorting.

0.95m Mudstone, red, trace silt.

3.10m Mudstone, purple-gray, trace silt.

0.36m Mudstone, light gray, some silt.

1.05m Mudstone, red, some silt.

0.53m Litharenite, fU to mL, moderate
sorting, subrounded.

0.85m Mudstone, red, some silt.

0.50m Litharenite, gray, fU to mL,
subrounded, moderate sorting.

0.53m Mudstone, light gray, purple lense

in middle, some silt.
Base of butte.

h

 

 

231

Measured Section 16, Eagle Point Section.
Mulkay Springs Quadrangle, T. 19 N., R. 115. W.,

Section 6, Swl/4,

SW1/4. From base to top of Eagle

Point. Through Fossil Locality BB117.

Unit Thickness

Description

Top of ridge

New Fork 2.75m

Litharenite, mU to ch, poorly

 

 

 

Tongue sorted, conglomeratic lenses
common, thickness variable but
Wasatch laterally persistent, lenticular
Formation cross-bedding.
0.10m Micrite, oncolitic.
8.50m Sublitharenite to Quartz arenite,
white to gray, mL to cL, moderate
sorting, thickness variable but
laterally persistent, lenticular
cross—bedding.
2.00m Mudstone, dark gray, trace silt.
0.60m Sublitharenite, gray, EU to mL,
well-sorted, subrounded.
2.50m Mudstone, dark gray, trace silt.
0.30m Sublitharenite, fU, moderately
sorted, subrounded.
Wilkins 0.85m Mudstone, dark gray, silty.
Peak 0.20m Micrite, light yellow,
Member, stromatolitic.
0.90m Mudstone, dark gray, silty.
Green 0.20m Micrite, light yellow,
River stromatolitic.
Formation 1.07m Mudstone, dark gray, silty.
0.45m Sublitharenite, light gray, fU,
moderate sorting, subrounded.
1.30m Mudstone, dark gray, some silt.
0.38m Micrite, light yellow,
stromatolitic.
2.80m Mudstone, dark gray-green, lighter
in colour towards top, almost tan,
some silt, trace sand.
0.20m Micrite, white, stromatolitic in
places.
1.45m Mudstone, dark gray-green, trace
silt.
0.15m Micrite, white, stromatolitic in
places.
1.30m Mudstone, gray-green, trace silt.
0.15m Micrite, white, highly
stromatolitic
4.20m Mudstone, tan to gray, emydid

turtle and Hyrachyps mergtps jaw

found near base.

.h

232

 

 

0.51m Litharenite, gray, mU at top,
Fontenelle conglomeratic at base, fines
Tongue, upwards, poor to moderate sorting,
subrounded, thickness variable.
Green 0.29m Mudstone, gray, trace silt.
River 0.71m Micrite, light yellow,
Formation stromatolitic in places.
5.50m Mudstone, light gray at top, green
gray at base, some silt.
0.39m Micrite, reddish gray.
6.10m Mudstone, gray, trace silt.
0.35m Micrite, white, stromatolitic in
places. .
9.05m Mudstone, gray, trace silt.
Buried sequence approximately 25m in thickness.
New Fork
Tongue 5.90m Litharenite, gray, unit thickness,
grain size and grain shape highly
Wasatch variable, conglomeratic lenses
Formation common, lenticular cross-beddinqi,
0.10m Mudstone, gray, calcareous, trace
silt, highly bioturbated.
0.75m Litharenite, gray, unit thickness,
grain size and grain shape highly
variable, conglomeratic lenses
common, lenticular cross-bedding.
1.00m Sparite, yellow, fossils not
Fontenelle apparent, very oolitic in places.
Tongue, 0.15m Siltstone, green-gray, some mud.
0.45m Sublitharenite, light gray, mL to
Green fU, well-sorted, cross-bedded.
River 0.90m Mudstone, red to maroon.
Formation 1.40m Mudstone, gray, silty.
1.10m Litharenite, gray, mL, moderately
sorted, subrounded.
2.88m Mudstone, gray, silty, some sand.
0.65m Litharenite, gray, mL, moderate
sorting, subrounded.
0.97m Mudstone, gray, silty, trace sand.
0.10m Micrite, yellow, oolitic/
ostracodal at top, crystalline at
base.
0.70m Siltstone, gray, trace sand.
0.90m Mudstone, gray, some silt.
0.30m Litharenite, gray, mL, moderate

sorting, subrounded.
Buried Sequence.

 

 

LIST OF REFERENCES

 

 

233

LIST OF REFERENCES

Andermann, G.G., 1955, Tertiary Deformational History of a
Portion of the North Flank of the Uinta Mountains in
the vicinity of Manila, Utah: Wyoming Geological
Association Guidebook, 15th Annual Field Conference:
103-133.

Arawmik, S.M., 1990, Stromatolites ip Paleobiology: A
Synthesis. (D.E.G. Briggs and P.R. Crowther eds.),
Blackwell Scientific Pubs, London, p.336-341.0

Baer, J.L., 1969, Paleoecology of cyclic sediments of the
lower Green River Formation, central Utah. Brigham
Young Univ. Geol. Studies, 16:(l)

Bartels, W.S., 1984, Osteology and Systematic Affinities of
the Horned alligator Ceratosuchus (Reptilia,
Crocodilia). Jour. Paleo., 58: 1347—1353.

Bartels, W.S. 1993, Niche Separation of Fluvial and
Lacustrine Reptiles from the Eocene Green River and
Bridger Formations of Wyoming. Jour. Vert. Paleo. 13
(supplement to 3): p. 25A.

Beard, K.C., 1988, New Notharctine Primate Fossils from the
Early Eocene of New Mexico and Southern wyoming and the
Phylogeny of Notharctinae. Am. Jour. Phys. Anthro., 75:
439-469.

Beard, K.C., Krishtalka, L., and Stucky, R.K., 1992,
Revision of the Wind River Faunas, Early Eocene of
Central Wyoming. Part 12. New Species of Omomyid
Primates (Mammalia: Primates: Omomyidae) and Omomyid
Taxonomic Composition Across the Early-Middle Eocene
Boundary. Ann. Carnegie Mus. 61: 39—62.

Blackstone, D.L., 1955, Notes on a Tectonic Map of Parts of
Southwestern Wyoming and Adjoining States: Wyoming
Geological Association Guidebook, 15th Annual Field
Conference: 122—124.

Bonillas, Y., 1936, The Dentition of Lambdotherium. Jour.
Mamm. 17: 139-142. '

n

234

Bown, T.M., 1982, Geology, Paleontology, and Correlation of
Eocene Volcaniclastic Rocks, Southeast Absaroka Range,
Hot Springs County, Wyoming. U.S.G.S. Prof. Paper 1201—
A: 1-75.

Bown, T.M., and Rose, K.D., 1976, New Early tertiary
Primates and a Reappraisal of some Plesiadapiformes.
Folia Primatol. 26: 109—138.

Bown, T.M., and Rose, K.D., 1984, Reassessment of Some Early
Eocene Omomyidae, with Description of a New Genus and
Three new Species. Folia. Primatol. 43: 97-112.

Bown, T.M., and Rose, K.D., 1987, Patterns of Dental
Evolution in Early Eocene Anaptomorphine Primates
(Omomyidae) from the Bighorn Basin, Wyoming: Jour.
Paleo. 61: supp. to no. 5, 1-162.

Bown, T.M., and Schankler, D., 1982, A Review of the
Proteutheria and Insectivora of the Willwood Formation
(lower Eocene), Bighorn Basin, Wyoming. U.S. Geol.
Surv. Bull. 1523: 79p.

Bradley, W.H., 1928, Algae Reefs and Oolites of the Green
River Formation. U.S. Geol. Surv. Prof. Paper 154-G:
203-223.

Bradley, W.H., 1959, Revision of Stratigraphic Nomenclature
of the Green River Formation of Wyoming: Bull. Amer.
Assoc. Petrol. Geol., 43(5): 1072-1075.

Bradley, W.H., 1963, Paleolimnology. ip Limnology in North
America. (D.G. Frey ed.) Univ. Wisconsin Press.

Bradley, W.H., 1964, Geology of the Green River Formation
and Associated Eocene rocks in Southwestern Wyoming and
adjacent parts of Colorado and Utah: United States
Geol. Surv. Prof. Paper 496A: 1—86.

Braunagel, L.C., and Stanley, K.O., 1977, Origin of
Variegated Red Beds in the Cathedral Bluffs Tongue of
the Wasatch Formation (Eocene), Wyoming: Jour. Sed.
Pet., 47:1201-1219.

Burke, J.J., 1934, New Duchesne River Rodents and a
Preliminary Survey of the Adjidaumidae. Ann. Carn.
Mus., 23: 391-398.

Carroll, R.L., 1988, Vertebrate Paleontology and Evolution,
W.H. Freeman and Co., New York, p.507-510.

 

235
Case, E.C., 1925, Note on a New Species of the Eocene
Crocodilian Allogpathosuchns, A. wartheni. Contrib.
Mus. Geol. Univ. Mich. 2(5): 93-97.

Clark, J., Beerbower, J.R., and Keitzke, K.K., 1967,

Oligocene Sedimentation, Stratigraphy, Paleoecology and

Paleoclimatology in the Big Badlands of South Dakota.
Fieldiana: Geol. Mem., 5: 1-158.

Cockerell, T.D.A., 1914, Tertiary Mollusca from New Mexico
and Wyoming. Bull. Amer. Mus. Nat. Hist., 33: 101-107.

Cope, E.D, 1872, Description of some New Vertebrata from
the Bridger Group of the Eocene, Proc. Am. Phil. Soc.,
22: 460-468, Seperata (Paleo. Bull., l & 2).

Donovan, J.H., 1950, Intertongueing of Green River and
Wasatch Formations in part of Sublette and Lincoln
Counties, Wyoming, ip Wyoming Geol. Assoc. Guidebook
5th Ann. Field Conf., Southwestern Wyoming, 1950: 59-
67.

Emry, R.J. 1989, A Tiny New Eocene Ceratomorph and Comments

on "Tapiroid" Systematics. Jour. Mamm., 70(4): 794-804.

Emry, R.J., 1990, Mammals of the Bridgerian (Middle Eocene)
Elderberry Canyon Local Fauna of Eastern Nevada. ip
Dawn of the Age of Mammals in the Northern Part of the
Rocky Mountain Interior, North America. (T.M. Bown and
K.D Rose eds.), Geol. Soc. Amer. Sp. Pap., 243: 187-
210.

Gaffney, E.S., 1975, The Systematics of the North American
Family Baenidae (Reptilia, Cryptodira). Bull. Amer.
Mus. Nat. Hist., 147: 241-320.

Gazin, C.L., 1952, The Lower Eocene Knight Formation of
Western Wyoming and its Mammalian Faunas. Smithsonian
Misc. Coll., 117(18): 1-82.

Gazin, C.L., 1953, The Tillodontia: An Early Tertiary Order
of Mammals. Smithsonian Misc. Coll., 121(10); 1-110.

Gazin, C.L., 1961. New Sciuravid Rodents from the Lower

Eocene Knight Formation of Western Wyoming. Proc. Biol.

Soc. Washington, 74:193—194.

Gazin, C.L., 1962. A Further Study of the Lower Eocene
Mammalian Faunas of Southwestern wyoming. Smithsonian
Misc. Coll. 144(1); 1—98.

 

 

236

Gazin, C.L., 1965. A Study of the Early Tertiary
Condylarthan Mammal Meniscotherium. Smith. Misc. Coll.
149(2): 1—110.

Gazin, C.L., 1968. A Study of the Eocene Condylarthan Mammal
Hyopsodps. Smith. Misc. Coll. 153(4): 1—104.

Gazin, C.L., 1976. Mammalian Faunal Zones of the Bridger
Middle Eocene, Smithson. Contrib. Paleobiol., 26: 1—25.

Gilmore, C.W., 1928, Fossil Lizards of North America. Nat.
Acad. Sci. Third Memoir 22: 1-201. Reprinted by
Riverside Museum Press, 1978.

Gilmore, C.W., 1838, Fossil Snakes of North America. Geol.
Soc. Amer. Sp. Paper 9: 1-96.

Gingerich, P.D., 1979, Phylogeny of Middle Eocene Adapidae
(Mammalia, Primates) in North America: Smilodepppg and
Hptharctus. Jour. Paleo., 53(1): 153—163.

Gingerich, P.D., 1983, Systematics of Early Eocene Miacidae
(Mammalia, Carnivora) in the Clark's Fork Basin,
Wyoming. Contribs. Mus. Paleont., Univ. Michigan, 26:
197-225.

Gingerich, P.D., 1989, New Earliest Wasatchian Mammalian
Fauna from the Eocene of Northwestern Wyoming:
Composition and Diversity in a Rarely Sampled High—
Floodplain Assemblage. Univ. Mich. Papers on Paleo. 28:
1—97.

Gingerich, P.D., and Gunnell, G.F., 1979, Systematics and
Evolution of the Genus Esphpnyg (Mammalia, Tillodontia)
in the Early Eocene of North America. Contribs. Mus.
Paleont., Univ. Michigan, 25: 125-153.

Gingerich, P.D., and Haskin, R.A., 1981, Dentition of Early
Eocene PelxcoQus jarrovii (Mammalia, Primates) and the
Generic Attribution of Species Formerly Referred to
Pelxcong. Contrib. Mus. Paleo. Univ. Mich. 25: 327—
337.

Gingerich, P.D., and Simons, E.L., 1977, Systematics,
Phylogeny, and Evolution of Early Eocene Adapidae
(Mammalia, Primates) in North America. Contrib. Mus.
Paleo. Univ. Mich., 22: 245-279.

Goodrich, C., 1944, Pleuroceridae of the Great Basin, Univ.
Mich., Mus. Zool., Occas. Papers, 485: 1-11.

 

 

 

237

Grande, L., 1984, Paleontology of the Green River Formation,
With a Review of the Fish Fauna. Geol. Surv. Wyoming.
Bull. 63: 1-333.

Granger, W., 1908, A Revision of the American Eocene Horses.
Bull. Amer. Mus. Nat. Hist., 24: 1-57.

Granger, W., 1914, On the Names of Lower Eocene Faunal
Horizons of wyoming and New Mexico. Bull. Amer. Mus.
Nat. Hist. 33: 201-207.

Gunnell, G.F., 1989, Evolutionary History of Microsyopoidea
(Mammalia, ?Primates) and the Relationship between
Plesiadapiformes and Primates. Univ. Mich. Papers on
Paleo. 27: 1—157.

Gunnell, G.F., in prep., Omomyid Primates (Tarsiiformes)
from the Bridger Formation, Middle Eocene, Southern
Green River Basin, Wyoming.

Gunnell, G.F., Bartels, W.S., Gingerich, P.D., and Torres,
V., 1992, Wapiti Valley Faunas: Early and Middle Eocene
Fossil Vertebrates From the North Fork of the Shoshone
River, Park County, Wyoming. Contrib. Mus. Paleo. Univ.
Mich. 28(11): 247-287.

Gunnell, G.F., Bartels, W.S., and Gingerich, P.D., 1993,
Paleocene-Eocene Boundary in Continental North America:
Biostratigraphy and Geochronology, Northern Bighorn
Basin, Wyoming. ip Vertebrate Paleontology in New
Mexico, New Mexico Mus. Nat. Hist. and Sci., Bull.

2: 137-144.

Gunnell, G.F., and Bartels, W.S., in press, Early Bridgerian
(Middle Eocene) Vertebrate Paleontology and
Paleoecology of the Southern Green River Basin,
Wyoming. in press.

Guthrie, D.A., 1967, The Mammalian Fauna of the Lysite
Member, Wind River Formation (Early Eocene) of wyoming.
Mem. So. Calif, Acad. Sci., 5: 53p.

Guthrie, D.A., 1971, The Mammalian Fauna of the Lost Cabin
Member, Wind River Formation (Lower Eocene) of Wyoming.
Ann. Carnegie Mus. 43(4): 47-113.

Hanley, J.H., 1974, Systematics, Paleoecology, and
Biostratigraphy of Nonmarine Mollusca from the Green
River and Wasatch Formations (Eocene), Southwestern
Wyoming and Northwestern Colorado. [Ph.D. Dissertation]
Univ. Wyoming, Laramie, Wyoming, 285p.

it..-

238

Hanley, J.H., 1976, Paleosynecology of Nonmarine Mollusca
from the Green River and Wasatch Formations (Eocene),
Southwestern Wyoming and Northwestern Colorado. ip
Structure and Classification of Paleocommunities, (R.W.
Scott and R.R. West eds.): Dowden, Hutchinson and Ross,
P. 235-261.

Hanley, J.H., 1977, Lithostratigraphic Relations, Nonmarine
Mollusca, and depositional Environments of a Portion of
the Green River and Wasatch Formations South of the
Rock Springs Uplift, Sweetwater County, Wyoming, With
Appendices of Measured Stratigraphic Sections. U.S.
Geol. Surv. Open file Rept. 77—588, 233p.

Hay, O.P., 1908, The Fossil Turtles of North America, Publ.
Carnegie Inst. Washington 75: 1-568.

Hayden, F.V., 1869, United States Geological and
Geographical Survey of the Territories, 3rd Annual
Report. p. 90.

Hayden, F.V., 1871, Preliminary Report of the United States
Geological Survey of wyoming. United States Geological
and Geographical Survey of the Territories., 4th Ann.
Rept., p. 142-144.

Hayden, F.V., 1873, United States Geological Survey of
Colorado and New Mexico. United States Geological
Survey of the Territories, 3rd Annual Report: 105—261.

Hecht, M.K., 1959. Amphibians and Reptiles. ip The Geology
and Paleontology of the Elk Mountain and Tabernacle
Butte Area, Wyoming. Bull. Amer. Mus Nat Hist. 117(3):
130-146.

Henderson, J., 1935, Fossil Non-Marine Mollusca of North
America, Geol. Soc. Amer. Sp. Papers 3: 1—313.

Holman, J.A., 1979, A Review of North American Tertiary
Snakes. Publ. Mich. St. Univ. Mus. 1(6): 203-260.

Jepsen, G.L., 1930, New Vertebrate Fossils from the Lower
Eocene of the Bighorn Basin, Wyoming. Proc. Amer. Phil.
Soc., 69: 117-131.

King, F.W., and Burke, R.L., eds., 1989, Crocodilian,
Tuatara, and Turtle Species of the World: A Taxonomic
and Geographic Reference. Assoc. Sys. Coll. Wash. D.C.,
216p.

Kitts, D.B., 1956, American Exgacophprium (Perissodactyla,
Equidae). Bull. Amer. Mus. Nat. Hist., 110(1): 1-60.

239

Kitts, D.B., 1957, A Revision of the Genus Orohippus
(Perissodactyla, Equidae). Amer. Mus. Nov., 1864: 1-40.

Knowlton, F.H., 1923, Revision of the Flora of the Green
River Formation. U. S. Geol. Surv., Prof. Pap. 131:
133-182.

Koenig, K.J., 1960, Bridger Formation in the Bridger Basin,
Wyoming: Wyoming Geological Association, 15th Annual
field Conference Guidebook: 163-168.

Korth, W.W., 1984, Earliest Tertiary Evolution and Radiation
of Rodents in North America, Bull. Carnegie Mus. Nat.
Hist. 24: 1-71.

Korth, W.W., and Evander, R.L. 1982, A New Species of
Orohippus (Perissodactyla, Equidae) from the Early
Eocene of Wyoming, Jour. Vert. Paleo., 2:167-171.

Krishtalka, L., and Stucky, R.K., 1983, Revision of the Wind
River Faunas, Early Eocene of Central Wyoming. Part 3.
Marsupalia, Ann. Carnegie Mus. 52: 205—228.

Krishtalka, L., and Stucky, R.K., 1984, Middle Eocene
Marsupials (Mammalia) from Northeastern Utah and the
Mammalian fauna from Powder Wash. Ann. Carnegie Mus.
53: 31—45.

Krishtalka, L., and Stucky, R.K., 1985, Revision of the Wind
River Faunas, Early Eocene of Central Wyoming. Part 7.
Revision of Diacogexig (Mammalia, Artiodactyla). Ann.
Carnegie Mus. 54(14): 413-486.

Krishtalka, L., and Stucky, R.K., 1986, Early Eocene
Artiodactyls from the San Juan Basin, New Mexico, and
the Piceance Basin, Colorado, Contrib. Geol., Univ.
Wyoming, Special Paper 3: 183—196.

Krishtalka, L., West, R.M., Black, C.C., Dawson, M.R.,
Flynn, J.J., Turnbull, W.D., Stucky, R.M., McKenna,
M.C., Bown, T.M., Golz, D.J., and Lillegraven, J.A.,
1987, Eocene (Wasatchian through Duchesnean)
Biochronology of North America, ip M.O. Woodburne,
editor, Cenozoic mammals of North America:
Geochronology and Biostratigraphy, Univ. Calif. Press.,
78-117.

Kuhn, O., 1968, Die Vorzeitlichen Krokodile (Oeben,
Krailling), 124p.

 

240

Langston, W. jr., 1975, ziphodont Crocodiles: Pristighpgpsug
vorax (Troxell), New Combination, from the Eocene of
North America. Fieldiana 33(16): 291—314.

La Rocque, A., 1960, Molluscan Faunas of the Flagstaff
Formation of Central Utah. Geol. Soc. Amer. Mem., 78:
1—100.

Lawrence, J.C., 1965, Wasatch and Green River Formations of
Southwestern Part of the Green River Basin, Wyoming
Geol. Assoc. Guidebook, 19th Annual Field Conference:
181-187.

Leidy, J., 1871, On the Fossil Vertebrates in the Early
Tertiary Formations of Wyoming. ip Annual Report of the
U.S. Geol. Surv. of the Territories (F.V. Hayden ed.)
5: 353-377.

Lesquereaux, L., 1878, The Tertiary Flora. United States
Geological Survey of the Territories. Rept. 7.

Lesquereaux, L., 1883, The Cretaceous and Tertiary Flora.
United States Geological Survey of the Territories.
Rept. 8.

Lillegraven, J.A., in press, Correlation of Palaeogene
Strata across Wyoming— A User's Guide ip Snoke, A.W.,
Steidtmann, J.R., and Roberts, 8., eds. Geology of
Wyoming, Memoir no. 5.

Logan, B.W., Hoffman, P., and Gebelein, C.D., 1974, Algal
Mats, Cryptalgal Fabrics and Structures, Hamelin Pool,
Western Australia: Amer. Assoc. Petrol. Geol. Memoir.

Loomis, F.B., 1907, Wasatch and Wind River Rodents, Amer.
Jour. Sci., 23: 123—130.

MacGinite, H.D., 1969, Eocene Green River Flora of
Northwestern Colorado and Northeastern Utah: Calif.
Univ. Pubs. Geol. Sci., 83: 1-203.

Marsh, O.C., 1871a, Notice of some New Fossil reptiles from
the Cretaceous and Tertiary Formations. Amer. Jour.
Sci. 1(3): 447-459.

Marsh, O.C., 1871b, Notice of some Fossil mammals from
the Tertiary Formation. Amer. Jour. Sci. 2: 34-45.

Marsh, O.C., 1872, Preliminary Description of New Tertiary
Mammals. Amer. Jour Sci., ser.3, 4(1): 122-128; 4(2-4):
291—567.

241

Matthew, W.D., 1909, The Carnivora and Insectivora of the
Bridger Basin, Middle Eocene. Memoirs Amer. Mus. Nat.
Hist. 9: 289-567.

Matthew, W.D., 1910, On the Osteology and Relationships of
Parggys and the Affinities of the Ischyromyidae. Bull.
Amer. Mus. Nat. Hist. 28: 43-71.

Matthew, W.D., 1915, "Insectivora (Continued), Glires,
Edentata," ip: Matthew, W.D., and Granger, W., A
Revision of the Lower Eocene Wasatch and Wind River
Faunas. Bull. Amer. Mus. Nat. Hist. 34: 1-104.

Matthew, W.D., 1918, "Edentata," ip: Matthew, W.D., and
Granger, W., A Revision of the Lower Eocene Wasatch and
Wind River Faunas. Part V., Bull. Amer. Mus. Nat. Hist.
38: 620-657.

McGrew, P.O., 1959, The Geology and Paleontology of the Elk
Mountain and tabernacle Butte Area, Wyoming. Bull.
Amer. Mus. Nat. Hist., 117: 117-176.

McGrew, P.O. and Sullivan, R., 1970, The Stratigraphy and
Paleontology of Bridger A: Univ. Wyom. Contrib. Paleo.
9: 66-85.

McKenna, M.C., 1975, Toward a Phylogenetic Classification of
the Mammalia, ip Phylogeny of the Primates (W.P.
Luckett and F.S. Szalay, eds.). Plenum Press, New York.

McKenna, M.C., 1976, Esthony; in the Upper Faunal
Assemblage, Huerfano Formation, Eocene of Colorado.
Jour. Paleont: 354-355.

McKenna, M.C., Robinson, P., and Taylor, D.W., 1962, Notes
on Eocene Mammalia and Mollusca from Tabernacle Butte,
Wyoming. Amer. Mus. Nov., 2102: 33p.

McKenna, M.C. and Simpson, G.G., 1959, A New Insectivore
from the Middle Eocene of Tabernacle Butte, Wyoming.
Amer. Mus. Nov., 1952: 1—12.

M'Gonigle, J.W., and Dover, J.H., 1992, Geologic Map of the
Kemmerer 30' x 60' Quadrangle, Lincoln, Uinta, and
Sweetwater Counties, Wyoming, Map I—2079.

Moore, R.C., (ed.) 1961, Treatise on Invertebrate
Paleontology. Geol. Soc. Amer. and Univ Kansas Press.

Moyle, P.B., and Cech, J.J.Jr., 1982, Fishes: An
Introduction to Ichthyology. Prentice Hall, New Jersey,
559p.

fl.

242

rdewberry, J.S., 1883, Brief Descriptions of Fossil Plants,

Chiefly Tertiary, from Western North America. U.S. Nat.

Mus. Proc., 5: 502-514.

rJewberry, J.S., 1898, The Later Extinct Floras of North
America. U.S. Geol. Survey Mon. 35.

C>riel, 8.5., 1962, Main body of Wasatch Formation Near La

Barge, Wyoming, Bull. Amer. Assoc. Petr. Geol., 46(12):

2161-2173.

(Ctriel, 8.5., and Tracy, J.I., 1970, Uppermost Cretaceous and

Tertiary Stratigraphy of Fossil Basin, Southwestern
wyoming. U.S.G.S. Prof. Paper 635: 1-53.

()53kmmnq H.F., 1929, The Titanotheres of Ancient Wyoming,
Dakota, and Nebraska. U.S. Geol. Surv. Monograph 55:
953p.

I?eagge, M.L., and Burr, M.B., 1991, Freshwater Fishes.
Peterson Field Guide Series vol. 42, Houghton-Mifflin
Co. Boston, p.29—32.

F’jtlsbry, H.A., 1946, Land Mollusca of North America (North

of Mexico). Acad. Nat. Sci. Philedelphia Mon. 3, II(1):

1—520.

I>Iledge, N.S., 1969, Paleoenvironments and Paleoecology of
part of the Lower Bridger Formation, South of Opal,
wyoming [M.S. Thesis], Laramie, Wyoming, University of
Wyoming, 74p.

Radinsky, L.B. , 1963, Origin and Early Evolution of North
American Tapiroidea. Bull. Peabody Mus. Nat Hist. 17:
1-115.

IRadinsky, L.B., 1966a, The Adaptive Radiation of the
Phenacodontid Condylarths and the Origin of the
Perissodactyla. Evolution 20: 408—417.

IRadinsky, L.B., 1966b, A New Genus of Early Eocene Tapiroid
(Mammalia, Perissodactyla). J. Paleo., 40: 740-742.

lRadinsky, L.B., 1967, Byzachxps, Chagpptherium, and the
Early Evolution of Helaletid Tapiroids. Amer. Mus. Nov.
2313: 1-23.

?Rage, J.C., 1977, An Erycinine Snake (Boidae) of the Genus
Calamagras from the French lower Eocene, with Comments
on the Phylogeny of the Erycinae. Herpetologica 33(4):
459-463.

 

243

 

Richardson, R.E., 1928, The Bottom Fauna of the Illinois
River, Illinois, 1919-1925. Illinois Nat. Hist. Surv.,
Bull., 17(12): 387-475.

Robinson, P., 1957., The Species of Notharctus from the
Middle Eocene. Yale Peabody Mus. Postilla, 28: 1-27.

 

Robinson, P., 1966, Fossil Mammalia of the Huerfano
Formation, Eocene, of Colorado. Bull. Yale Peabody Mus. flW-i
Nat. Hist. 21:1-95.

Roehler, H.W., 1965, Early Tertiary Depositional Environmen
ts in the
Rock
Springs ' u
Uplift
Area, ip:
Devoto,
R.H., and
Bitter,
R.K.,
eds.,
Sedimentat
ion of
Late
Cretaceous
and
Tertiary
Outcrops.
Rock
Springs
Uplift:
Wyoming
Geol.
Assoc.
Guidebook,
19th Field
Conference
, Casper,
Wyoming:
140-150.

Roehler, H.W., 1992, Correlation, Composition, Areal
Distribution, and Thickness of Eocene Stratigraphic
Units, Greater Green River Basin, Wyoming, Utah and
Colorado, United States Geol. Surv. Prof. Paper 1506-E:
1-49.

Rose, K.D., 1981, The Clarkforkian Land-Mammal Age and
Diversity across the Palaeocene-Eocene Boundary. Univ.
Mich, Pap. Paleo., 26: 1-197.

 

244

Rose, K.D., 1982, Skeleton of Diacodexis, Oldest Known
Artiodactyl. Science, 216: 621-623.

Rose, K.D., 1985, Comparative Osteology of North American
Dichobunid Artiodactyls. Jour. Paleontology 59(5):
1203-1206.

Rose, K.D., and Emry, R.J., 1983, Extraordinary Fossorial
Adaptations in the Oligocene Palaeanodonts
Epoicotherium and Xgnocranium (Mammalia). Jour. Morph.
175: 33-56.

Rose, K.D., and Walker, A., 1985, The Skeleton of Early
Eocene Cantius, Oldest Lemuriform Primate. Am. Jour.
Phys. Anthro., 66: 73-89.

Rubey, W.W., 1955, Early Structural History of the
Overthrust Belt of Western Wyoming and Adjacent States:
Wyoming Geological Association Guidebook, 15th Annual
Field Conference: 125-126.

Schaeffer, B., 1947, Notes on the Origin and Function of the
Artiodactyl Tarsus. 1356: 1-24.

 

h

 

245

Schankler, D.M., 1980, Faunal Zonation of the Central
Bighorn Basin, Wyoming. Univ. Mich. Pap. Paleo., 24:99-
114.

Schultz, A.R., 1920, Oil Possibilities In and Around Baxter
Basin, in the Rock Springs Uplift, Sweetwater County,
Wyoming, United States Geol. Surv. Bull., 702: 24-29.

Setoguchi, T., 1975, Paleontology and Geology of the
Badwater Creek Area, Central Wyoming. Part 11. Late
Eocene Marsupials. Ann. Carnegie Mus., 45: 263-275.

Shuster, M.W., and Steidtmann, J.R., 1988, Tectonic and
Sedimentary Evolution of the northern Green River
Basin, Western wyoming, Geological Survey of America
Memoir 171: 515-529.

Simons E.L., 1962, A New Eocene Primate Genus Cantius and a
Revision of some Allied European Lemuroids. Bull. Brit.
Mus. Nat. Hist. Geol., 7:1-36

Simpson, G.G., 1930, Allogppthosuphus mooki, a new crocodile
from the Puerco Formation. Amer. Mus. Nov. 445: 1-16.

 

Simpson, G.G., 1931, Metacheirogzs and the Edentata. Bull.
Amer. Mus. Nat. Hist. 59: 295-381.

Simpson, G.G., 1945, The Principles of Classification and a
Classification of Mammals. Bull. Amer. Mus. Nat. Hist.
85: 1-350.

Simpson, G.G., 1948, The Eocene of the San Juan Basin, New
Mexico. Amer. Jour. Sci., vol. 246: 257-282; 363-385.

Simpson, G.G., 1959, two New Records from the Bridger Middle
Eocene of Tabernacle Butte, Wyoming. Amer. Mus. Nov.
1966: 5p.

Sinclair, W.J., 1914, A Revision of the Bunodont
Artiodactyla of the Middle and Lower Eocene of North
America. Bull. Amer. Mus. Nat. Hist., 33: 267-295.

Stucky, R.K., 1984a, Revision of the Wind River Faunas.
Early Eocene of Central Wyoming. Part 5. Geology and
Biostratigraphy of the Upper Part of the Wind River
Formation. Northeastern Wind River Basin. Ann. Carnegie
Mus. 53(9): 231-294.

Stucky, R.K., 1984b, The Wasatchian-Bridgerian Land Mammal
Age Boundary (Early to Middle Eocene) in Western North
America. Ann. Carnegie Mus. 53(12): 347-382.

 

I. U'L'W-Iflww .

 

"- 1 a

 

 

246

Stucky, R.K., and Krishtalka, L., 1983, Revision of the Wind
River Faunas, Early Eocene of Central Wyoming. Part 4.
The Tillodontia. Ann. Carnegie Mus. 52(17): 375-391.

Stucky, R.K., and Krishtalka, L., 1990, Revision of the Wind
River Faunas, Early Eocene of Central Wyoming. Part 10.
Bunpphorous (Mammalia, Artiodactyla) Ann. Carnegie Mus.
59(2): 149-171.

Sullivan, R.M., 1979, Revision of the Palaeogene genus
Glyptosaurus (Reptilia, Anguidae), Bull. Amer. Mus.
Nat. Hist. 163(1): 1-72.

Sullivan, R., 1980, A Stratigraphic Evaluation of the Eocene
Rocks of Southwestern Wyoming: Geological Survey of
Wyoming, Report of Investigations 20: 1-50.

Surdam, R.C., and Wolfbauer, C.A., 1975, Green River
Formation, Wyoming: playa-lake complex. Geol. Soc.
Amer. Bull., 86: 335-345.

Surdam, R.C., and Wray, J.L., 1976, Lacustrine
Stromatolites, Eocene Green River Formation, Wyoming
(Lake Gosiute only), ip Stromatolites (M.R. Walter
ed.), Elsevier, p.535-541.

Swain, F.M., 1964, Early Tertiary Freshwater Ostracoda from
Colorado, Nevada, and Utah, and their stratigraphic
distribution. Jour. Paleo., 38(2): 256-280.

Szalay, F.S., 1969, Mixodectidae, Microsyopidae, and the
Insectivore-Primate Transition. Bull. Amer. Mus. Nat.
Hist., 140(4): 194-330.

Szalay, F.S., 1976, Systematics of the Omomyidae
(Tarsiiformes, Primates) Taxonomy, Phylogeny, and
Adaptations. Bull. Amer. Mus. Nat. Hist. 156(3): 157-
450.

Szalay, F.S., and Delson, E., 1979, Evolutionary History of
the Primates. Academic Press, 580p.

Taylor, D.W., and Sohl, N., 1962, An Outline of Gastropod
Classification. Macalogia, 1(1): 7-33.

Troxell, E.L., 1925, The Bridger Crocodilians, Amer. Jour.
Sci., ser. 5, 9: 29-72.

Turnbull, W.D., 1978, The Mammalian Faunas of the Washakie
Formation, Eocene Age, of Southern wyoming. Pt. 1:
Introduction: The Geology, History, and Setting.
Fieldiana: Geol. 33: 569-601.

 

 

247

Van Valen, L. 1967, New Palaeocene Insectivores and

West,

West,

West,

West,

West,

West,

West,

West,

West,

Insectivore Classification. Bull. Amer. Mus. Nat.
Hist., 135(5): 218—284.

R.M., 1969, Biostratigraphy of Fluvial Sediments of
the Upper Wasatch formation in the Northern Green River
Basin, Wyoming. Univ. Wyoming. Contrib. Geol. 8: 184-
196.

R.M., 1970, Sequence of Mammalian Faunas of Eocene Age
in the Northern Green River Basin, wyoming. Jour.
Paleo., 14: 142-147. '

R.M., 1973, Geology and Mammalian Paleontology of the
New Fork- Big Sandy Area, Sublette County, wyoming.
Fieldiana: Geology 29: 1-193.

R.M., 1976, Paleontology and Geology of the Bridger
Formation, Southern Green River Basin, southwestern
Wyoming. Part 1. History of Field Work and geological
setting, Milwaukee Public Museum, Contrib. Biol. Geol.
7: 1-12.

R.M., 1979, Paleontology and Geology of the Bridger
Formation, Southern green River Basin, Southwestern
wyoming. Part 3. Notes on Hyopsodus. Contrib. Biol.
Geol. Milwaukee Public Mus., 25: 1-52.

R.M., 1984, Paleontology and Geology of the Bridger
Formation, Southern Green River Basin, Wyoming. Part 7.
Survey of Bridgerian Artiodactyla, Including
Description of a Skull and Partial Skeleton of
Antiacodpn gxgppppg. Contrib. Biol. Geol., Milwaukee
Public Mus., 56:1-47. .

R.M., 1990, Vertebrate Paleontology of the Green river
Basin, wyoming, 1840-1910: Earth Science History, 9(1):
45—56.

R.M., and Dawson, M.R., 1973, Fossil Mammals from the
Upper Part of he Cathedral Bluffs Tongue of the Wasatch
Formation (Early Bridgerian), Northern Green River
Basin, wyoming. Univ. Wyoming Contrib. Geol., 12:33-41.

R.M., and Hutchinson, J.H., 1981, Geology and
Paleontology of the Bridger Formation, Southern Green
River Basin, Southwestern Wyoming. Pt 6: The fauna and
Correlation of Bridger E. Milwaukee Pub. Mus. Contrib.
Biol. Geol., 46: 1-8.

 

. I},

248

Wiley, E.O., 1976, The Phylogeny and Biogeography of Fossil
and Recent Gars (Actinopterygii, Lepisosteidae). Univ
Kansas Mus. Nat Hist. Misc. Publ., 64: 1-111.

Wilson, R.W., 1938, Review of some Rodent Genera from the
Bridger Eocene. Amer. Jour. Sci., ser.5, 35: 123-137

Wilson, R.W., 1940, Californian Paramyid Rodents. Carn.
Inst. Washington Publ., 514: 59-83.

Wood, A.E., 1959, Rodentia. IQ The Geology and Paleontology
of the Elk Mountain and Tabernacle Butte Area, Wyoming,
(P.O McGrew ed.). Bull. Amer. Mus. Nat. Hist., 117:
157-169.

Wood, A.E., 1962, The Early Tertiary Rodents of the Family
Paramyidae, Trans. Amer. Phil. Soc. 52(1): 1:261.

Wood, A.E., 1965, Small Rodents from the early Eocene Lysite
Member, Wind River Formation of Wyoming. Jour. Paleo.
39: 124-134.

Wood, C.B., 1966, Stratigraphy and Paleontology of the
Bridger Formation Northeast of Opal, Lincoln County,
Wyoming [M.S. Thesis]: Laramie, Wyoming, University of
Wyoming, 112p.

Wood, H.E., 1934, Revision of the Hyrachyidae. Bull.
Amer. Mus. Nat. Hist., 67(5): 181-295.

Wood, H.E., Chaney, R.W., Clark, J., Colbert, E.H., Jepsen,
G.L., Reeside, J.B. Jr., and Stock, C., 1941,
Nomenclature and Correlation of the North American
Continental Tertiary. Bull. Geol. Soc. Amer. 52: 1-48.

Woodburne, M.O., editor, 1987, Cenozoic Mammals of North
America: Geochronology and Biostratigraphy, Berkeley
and Los Angeles, Univ Calif Press, 336p.

Wortman, J.L., 1896, Species of szapotherium and allied
Perissodactyl from the Wahsatch and Wind River Beds of
North America. Bull. Amer. Mus. Nat. Hist., 8: 81-110.

Wortman, J.L., 1901, Studies of Eocene Mammalia in the Marsh
Collection, Peabody Museum. Am. Jour. Sci. 6: 333—348,
437-450, 7: 193-206, 281-296, 377-382, 421-432.

Zonneveld, J-P., 1994, Differential Preservation of Fossil
Vertebrates in the Eocene Wasatch, Bridger, and Green
River Formations of Southwestern Wyoming, Geol. Soc.
Amer., Abs. with Prog. (in press).

 

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Green River Fm.

 

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Green River Fm.

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PLATE 2. CORRELATION OF MEASURED
STRATIGRAPHIC SECTIONS WITHIN THE
EOCENE WASATCH, GREEN RIVER AND
BRIDGER FORMATIONS, LINCOLN AND
UINTA COUNTIES, WYOMING.

Section ‘A' from Bartels, l989-I992,
unpublish field notes.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

   
 

 

 

  

 

In part after M'Gonigle and Dover, 1992.

 

 

 
  
 

 

 

 

MN
16°
PLATE 1. GEOLOGIC MAP OF THE DESERTION 1'36 820
POINT-LITTLE MUDDY AREA,SOUTHWESTERN T-ZON- 11 — o 1 2 I 3 4 “5
GREEN RIVER BASIN, WYOMING. Tgw “9" Kilometers
CENOZOIC
Twu
Bridger Formation
-Whiskey Butte Bed
R.ll6w. R.|l5w. Green River Formation
-Craven Creek Bed, Laney Member
K -Wilkins Peak Member
. e R Tsrwn .. Ai‘ i —
A e . a e. e g c |Tgf iFontenelle Tongue
FL Tap Hat Butte -
, Wasatch Formation
-Upper Member
9‘3
wa -New Fork Tongue
6 Desertion Point -La large member
MESOZOIC
Tglc -Undifferentiated Cretaceous
Lincoln CO
men. u
Uinta CO .
TW“ Measured Section
I2
Big ”m" " ~c .9 _‘ Cont ct
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I '° Tglc

 
 

 

 

 

 

 

 
 

 

 

 

 

 

 

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