\ NW? J W13) 2.21 We“ 3 1293 4: l ) 2213;;2 O 8: L {LS ix: xi pi: Y Mich2g 22:: 35.32:: . Um 2123232, -.' L 1...; ‘50.— ”35252513229133 This is to certify that the thesis entitled IDWER VEKIEBRA'I'ES FRCM SWAIN QUARRY, "RDKI‘ UNION FORMATION ," MIDDLE PAIFDCENE (TORREJONIAN) , CARHDN COUNI'Y, WYCNING presented by ROBERT M. SULLIVAN . has been accepted towards fulfillment of the requirements for Ph.D. {1951-99 in Geology /%/ fessor Date W/ 0-7639 . (3' ”$1.1“ a: 92M: 25¢ per day per item _J [gflg‘ “f museum mam menus: ‘41.: 1‘“ Place in book return to remove -« ‘ change from circuiation records ABSTRACT LOWER VERTEBRATES FROM SWAIN QUARRY "FORT UNION FORMATION", MIDDLE PALEOCENE (TORREJONIAN), CARBON COUNTY, WYOMING By Robert M. Sullivan The Swain Quarry local fauna (middle Paleocene: Torrejonian) of Carbon County, wyoming, has yielded the largest Paleocene lower vertebrate microfauna described to date. Fish are sparsely represented by an indeterminate teleost and by Amia fragosa. The amphibians are repre- sented by the urodeles Scapherpeton, cf. Opisthotriton and Habrosaurus. A fragment of a dentary is referred to the Crocodilia. The lizards comprise sixty-seven percent of the entire lower vertebrate microfauna based on minimum number of individuals, and thus form the most important component. Lizard genera noted from.Swain Quarry include cf. Contogenys, Paleoxantusia, Exostinus, Odaxosaurus and cf. Provaranosaurus. A number of indeterminate specimens are referred to the subfamily Glyptosaurinae. A new lizard, Swainiguanoides milleri n. gen., n. sp., represents the Robert M. Sullivan oldest known North American iguanid. The subfamily Odaxosaurinae, new subfamily, is established for the primi- tive anguid Odaxosaurus. Machaerosaurus torrejonensis is identified for the first time by material other than the holotype. Helagras prisciformis, a Torrejonian snake, is present in the Swain Quarry local fauna. Despite the relatively large size of the lower verte- brate fauna from Swain Quarry, the sample size is too small to allow detailed ecological interpretation. General com- parisons of the fauna with other Paleocene faunas, as well as the late Cretaceous faunas, show that the aquatic habi— tat is relatively unchanged across the Cretaceous- Tertiary boundary which is in agreement with analysis of previously studied Paleocene herpetofaunas. Diversifi- cation of anguid lizards may have occurred in response to the apparent Paleocene decrease in the diversity of other lizard families as documented by earlier studies. In loving dedication to my parents Robert F. and Marian E. Sullivan ii ACKNOWLEDGEMENTS I am indebted to Eugene Gaffney and Charlotte Holton (American Museum of Natural History) for the loan of the Swain Quarry Lower vertebrate microfauna. I thank Michael Greenwald and J. Howard Hutchinson (University of California-Berkeley) for the loan of the Odaxosaurus piger specimens. J. Kieth Rigby Jr. (Bureau of Land Management, Albuquerque) was helpful in furnishing me with additional information regarding the fauna, collecting techniques and geology of Swain Quarry. Richard Estes (San Diego State University) critically reviewed the manuscript and con- ferred with me on the material and I am very grateful for his time and suggestions. I thank my doctoral committee members Robert L. Anstey, Chilton E. Prouty and Richard Seltin for their guidance and interest throughout the course of my program at Michigan State University. Special thanks are extended to my adviser J. Alan Holman, whose guidance and support made this study possible. The illustrations of the specimens were made by Merald Clark and I thank him for his time and meticulous care in making these drawings. iii TABLE OF CONTENTS LIST OF TABLES. LIST OF FIGURES . INTRODUCTION. GEOLOGIC SETTING. SYSTEMATIC PALEONTOLOGY . Class Osteichthyes Order Amiiformes Family Amiidae. Infraclass Teleostei Teleostei Incertae Sedis. Class Amphibia Order Caudata Suborder Ambystomatoidea Family Scapherpetontidae. Suborder Proteida Family Batrachosauroididae. Family Sirenidae. Class Reptilia Order Crocodilia Suborder Eusuchia Family Crocodylidae . Order Lacertilia Suborder Iguania Family Iguanidae. Suborder Scincomorpha Family Scincidae. iv 10 ll 13 l3 l7 Family Xantusiidae. Family Xenosauridae . Suborder Anguimorpha Family Anguidae Subfamily Odaxosaurinae, New Subfamily . Subfamily Glyptosaurinae . Subfamily Glyptosaurine and/or Odaxosaurine Indeterminate . Subfamily Anguinae . Family Parasaniwidae. Indeterminate Lacertilia. Order Serpentes Family Boidae Subfamily Erycinae . COMPARISON OF LATE CRETACEOUS AND PALEOCENE LOWER VERTEBRATE FAUNAS OF THE ROCKY MOUNTAIN REGION, NORTH AMERICA . . . . . . . . . SUMMARY . LITERATURE CITED. 22 26 28 29 36 37 37 40 52 54 Table I. Table 2. Table 3. LIST OF TABLES List of Minimum Numbers of Individuals (MNI) and Percentages of Higher Taxa from Swain Quarry . . . . . . . Occurrences of Lower Vertebrate Taxa from the Three Major Paleocene Lower Vertebrate Localities of North America. Time-Stratigraphic Distribution of the Swain Quarry Lower Vertebrates. vi 43 45 Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure ha 2d P‘ r4 2d F“ 2A r4 2a P‘ r4 <3 \0 WNH LIST OF FIGURES Location of Swain Quarry. Amia fragosa. cf. Amia fragosa. Scapherpeton tectum . cf. Scapherpeton tectum . cf. Opisthotriton kayi. Habrosaurus dilatus Habrosaurus dilatus Swainiguanoides milleri n. gen., n. sp. cf. Swainiguanoides milleri . cf. Contggenys sloani . Paleoxantusia fera. Paleoxantusia fera. Exostinus cf. E. lancensis. Odaxosaurus piger . Odaxosaurus piger . Glyptosaurinae Indeterminate. Glyptosaurinae Indeterminate. Machaerosaurus torrejonensis. Machaerosaurus torrejonensis. vii Figure Figure Figure Figure Figure Figure Figure Figure 21. 22. 23. 24. 25. 26. 27. 28. viii Machaerosaurus torrejonensis. Machaerosaurus torrejonensis. cf. Machaerosaurus torreionensis. Anguidae Indeterminate. Anguidae Indeterminate. Anguidae Indeterminate. cf. Provaranosaurus sp. Helagras prisciformis INTRODUCTION Paleocene vertebrate faunas are rare. In North America only two large Paleocene lower vertebrate micro- faunas have been studied (Estes, 1975, 1976) but they are not nearly as large or as diverse as the late Cretaceous lower vertebrate assemblages reported by Estes (1964) and Estes et a1. (1969). Most records of Paleocene lower vertebrates are from isolated accounts in Gilmore (1928, 1938 and 1942), Matthew (1937) and additions by Estes (1965b). Since the Paleocene is so poorly documented, the Swain Quarry lower vertebrate microfauna is an extremely important supplement to these previous studies of this major gap in the geologic record of the evolution of many vertebrate groups. Swain Quarry, a major middle Paleocene (Torrejonian) site, was recently studied by J. Keith Rigby Jr. The mam- malian fossils and geology of this quarry form the basis of his doctoral dissertation at Columbia University in 1977. Swain Quarry lies in the south-central part of Wyoming and has been known since the late 19505 as a potentially pro- ductive site for Paleocene microvertebrates. Rigby (1977) reviewed the historical aspects of Swain Quarry, along with its geology and geography and has studied the diverse micromammalian fauna. The lower vertebrate microfauna was obtained with the ‘mammalian fossils by screening projects conducted by Frederick Szalay in 1964, followed by more intensive screening efforts of J. Keith Rigby Jr. in 1972 and 1973. All fossils recovered from this quarry are in the collec- tions of the American Museum of Natural History, New York (AMNH). Preliminary identification of some of the lower vertebrates from Swain Quarry were made by Richard Estes and Eugene Gaffney, but no thorough study of these lower vertebrates has occurred and a number of the preliminary identifications need to be reviewed. This study supplements Rigby's (1977) work on the geology and the fossil mammals from Swain Quarry. The present study is not only important because of the rarity of Paleocene lower vertebrates in general, but is signi- ficant in that this small lower vertebrate microfauna occurs with a very large mammalian one whose time- stratigraphic position is well documented. GEOLOGIC SETTING Swain Quarry is located in south-central wyoming, 37 kilometers northwest of Baggs, in the SE%, NEa, Sec. 3, T15N, R92W, Doty Mountain quadrangle (Figure l). The quarry is situated 377 meters above the base of the "Fort Union Formation." Rigby (1977) thoroughly described the local geology, topography and historical aspects of Swain Quarry which are only briefly summarized here. IMDNTIJUK WYOMING NEBRASKA l g ‘ SWAIN QUARRY UTAH 7 commno Figure 1. Location of Swain Quarry. The local stratigraphy of the Swain Quarry region finds the late Cretaceous Lance Formation, overlain by the "Fort Union Formation" (Paleocene), which in turn is over- lain by the Wasatch Formation (Hiawatha member). Swain Quarry occurs in the lower part of the "Fort Union 1 and is one of eight localities from that unit Formation" which has yielded fossil vertebrates. The quarry is part of a "block" consisting of massive cross-bedded sandstones that grade laterally into carbonaceous shales, mudstones and siltstones (Rigby, 1977). Swain (1957) presented evi- dence for local upper and lower lithologic units in this part of the "Fort Union Formation" but Rigby (1977) believes that the terms "lower" and "upper" should be applied locally in a relative sense. The Swain Quarry local fauna was assigned a Torrejonian age based on fossil mammals by Rigby (1977), who compared the mammalian taxa of Swain Quarry to those of Gidley and Rock Bench quarries and to those of several sites in the Nacimiento Formation of the San Juan Basin, New Mexico. He concluded that the fauna from Swain Quarry was phylogenetically more derived than that of Gidley 1Reference to the rocks at the Swain Quarry site as belong- ing to the "Fort Union Formation” is questionable owing to the poorly understood local stratigraphy (Rigby, 1977). The formation lacks stratigraphic continuity with the type section that occurs at Fort Union, Montana. The rocks at Swain Quarry have been referred to this formation solely on the basis of gross lithology and similar fauna and flora content. Quarry, but was contemporaneous with those of the other Paleocene sites. Recently, in an unpublished correlation chart, Sloan (1979) placed Swain Quarry slightly above Gidley Quarry and slightly below Rock Bench Quarry, with all three quarries being equivalent in age (late most Torrejonian). SYSTEMATIC PALEONTOLOGY Class Osteichthyes Order Amiiformes Family Amiidae Genus Amia Amia fragosa (Jordon, 1927) Referred material: AMNH 14303 and 14308 (Figure 2), oral teeth. Figure 2. Amia fragosa (AMNH 14308), oral teeth. X 8. Remarks: AMNH 14303 and 14308 consist of a relatively large cluster of bulbous teeth with faintly wrinkled crowns. These teeth are characteristic of the type found in the oral cavity of Amia fragosa and are here referred to that species. Estes et a1. (1969) have noted that amiids are common in the late Cretaceous and Paleocene of both North America and Europe. cf. Amia fragosa Referred material: AMNH 14301 (Figure 3), tooth. Figure 3. cf. Amia fragosa (AMNH 14301), tooth. X 20. Remarks: This specimen is typical of the marginal teeth of the maxilla, premaxilla and dentary of Amia fragosa and is here provisionally referred to this species. The tooth measures approximately 3 mm in total length and is divided into two nearly equal parts. The enameloid part of the tooth is cone-shaped and slightly recurved at the tip (Figure 3). Infraclass Teleostei Teleostei Incertae Sedis Referred material: AMNH 14302, anterior part of right dentary. Remarks: The length of this incomplete specimen is approximately 3 mm. Based on the presence of clustered tooth bases, enough of it is preserved to indicate that it represents an anterior part of the right dentary of a small teleost. It is not possible to refer this specimen to any particular taxon. Class Amphibia Order Caudata Suborder Ambystomatoidea Family Scapherpetontidae Genus Scapherpeton Scapherpeton tectum Cope, 1876 Referred material: AMNH 12015 through 12022 (Figure 4), atlantes and AMNH 12024, trunk vertebra. Figure 4. Scapherpeton tectum.(AMNH 12017), atlas. a. axial view; b. ventral view. X 10 Remarks: The fragmentary Scapherpeton tectum material in Swain Quarry adds little to our knowledge to the osteology of this urodele. This species is mainly repre- sented mostly by its distinctive atlantes which can be dis- tinguished from those of the scapherpetontid Lisserpeton (Estes, 1965a) on the basis of the absence of an excavated ventral pit posterior to the condyle. The presence of eight atlantes representing a minimum of eight individuals of Scapherpeton tectum points to either the probability of a "pickers bias" in sorting concentrate or selective transport. In both cases the distinctive morphology may be the reason for the recovery. The possibility of "picker's bias" in sorting raises a question as to the degree the entire lower vertebrate fauna from Swain Quarry was selec- tively sorted, a question that will be addressed later. Estes (1964, 1969a, 1975 and 1976) and Estes et al. (1969) reported that Scapherpeton tectum occurs from the late Cretaceous through the Paleocene of North America. cf. Scapherpeton tectum Referred material: AMNH 12009 (Figure 5), medial part of left dentary and 12010, medial part of left dentary. Remarks: Both of these specimens lack teeth and are provisionally referred to Scapherpeton tectum based on the shallow breadth of the dentary. 10 .“'- ~-.‘,-.40 .... ..I"-“" Ovu- 1' )‘ . -o--o.u.....-. - ‘I‘r' r ".o.-."- y ' ' . . "v.1!“- . a: .".‘."- ’\-'?'-'- ‘-"-':.‘- n7.“ ' ‘ 3 - ._ . .- - Figure 5. cf. Scapherpeton tectum (AMNH 12009), medial part of left dentary (lingual view). X 15. Suborder Proteida Family Batrachosauroididae cf. Opisthotriton kayi Auffenberg, 1961 Referred materials: AMNH 12061, anterior part of right dentary; AMNH 12204, anterior part of left dentary; AMNH 12206, anterior part of right dentary; AMNH 12207, medial part of right dentary; and AMNH 14305 (Figure 6), atlas. Remarks: The fragmentary dentaries are referred to this species on the basis of the spacing of the basal tooth attachment and the breadth of the dentaries. Some of this material may be referrable to Scapherpeton but owing to the incomplete nature of these specimens, precise taxonomic assignment is uncertain. The atlas (AMNH 14305, Figure 6) is missing the longitudinally-elongate neural crest that distinguishes it from Prodesmodon (Naylor, 1979), but the cotyles appear to be more circular than the ovoid cotyles ll Figure 6. cf. Opisthotritonk ayi (AMNH 14305), atlas. a. axial view, b. ventral View. X25. of Prodesmodon and thus this specimen is provisionally referred to Opsithotriton. Family Sirenidae Genus Habrosaurus Habrosaurus dilatus Gilmore 1928 Referred material: AMNH 12011, anterior part of left dentary; AMNH 12012, medial part of right dentary; AMNH 12013, medial part of right dentary; AMNH 12023 (Figure 7), atlas; AMNH 12205 (Figure 8), nearly complete left dentary; AMNH 12208, medial part of left dentary; and AMNH 14304, medial part of left dentary. Remarks: The atlas (AMNH 12023, Figure 7) is referred to Habrosaurus dilatus based on the broad flattened ventral 12 Figure 7. Habrosaurus dilatus (AMNH 12023), atlas. a. axial View; B. ventral view. X 7. surface, presence of a deep lateral fossa behind the condyles and a circular cotyle. The teeth of all preserved dentaries are broken. Reference to Habrosaurus dilatus is based primarily on the wide tooth spacing and the wider breadth of the individual dentaries. These two features Figure 8. Habrosaurus dilatus 1(AMNH 12205), left dentary (lingual view). X— 13 allow separation from the other urodeles Opisthotriton, Scapherpeton and Lisserpeton (Estes, 1964, 1965a). Estes (1964) extensively reviewed Habrosaurus dilatus Gilmore, 1928 and referred it to the family Sirenidae. Habrosaurus dilatus is known from the late Cretaceous (Estes, 1964) through the middle Paleocene (Estes, 1976). Class Reptilia Order Crocodilia Suborder Eusuchia Family Crocodylidae Genus and species Indeterminate Referred material: AMNH 12067, two fragments of right dentary. Remarks: The larger fragment of this specimen mea- sures 12 mm in length and is referred to the Crocodylidae based upon the pitted labial surface of the dentary. This specimen may represent Allognathosuchus sp. which occurs in the early Paleocene deposits of North America, but this taxonomic assignment cannot be made without the teeth. Order Lacertilia Suborder Iguania Family Iguanidae Swainiguanoides milleri n. gen., n. sp. Holotype: AMNH 12082 (Figure 9), medial part of right dentary. 14 Figure 9. Swaini uanoides milleri n. gen., n. sp. (AMNH IEOBITgEy5377—EeHIEI—pirt of right dentary. a. labial view; b. lingual view. X 10. Paratype: AMNH 12081, medial part of right dentary. Type locality: Swain Quarry, Fort Union Formation, Carbon County, Wyoming. Age: Middle Paleocene (Torrejonian). Etymology: The generic name is established, in part, for the Swain Quarry from which the specimen came; iguanoides from the greek for small inguana—likg. The specific name is established in honor of Alan V. Miller. Diagnosis: Differs from living and fossil iguanines by the following combination of characters: teeth, non- striated, anterior-posteriorly compressed and compact with their bases expanded lingually. Teeth in cross section are ovoid and extend a little less than half their height beyond the parapet of the jaw. Tooth crowns are compressed linguolabially with four tiny cusps. The two inner cusps form a plateau in the middle that equally divides the tooth crown region into three separate parts. Two lateral cusps on either side are located below the medial cusps and form 15 a slope of about 45°. Meckelian groove deep; both the dental shelf and ventral dentary border are nearly in the same vertical plane with a well defined sulcus dentalis. Intramandibular septum fused with a V-shaped notch at the posterior border. Description: AMNH 12082 (Figure 9), measures 7 mm in length and represents a large part of the medial and posterior part of the dentary. One complete tooth and parts of four others are preserved. Spaces for three addi- tional teeth are evident. The labial side of the dentary is relatively smooth, with two mental foramina located in the middle and anterior parts of the preserved dentary. The paratype (AMNH 12081) measures 6 mm and is also a fragment of a right dentary. The tooth crowns are not pre- served in this specimen, but it agrees in every other way with the holotype. Basal parts of five teeth are pre- served and spaces for two are present. The labial side of the dentary is relatively smooth with one mental foramen present in the middle. Both specimens display a deep Meckelian groove with well developed dorsal and ventral borders formed by the sulcus dentalis and the ventral lingual edge of the dentary, respectively, thus indicating that the splenial was restricted. Discussion: Swainiguanoides milleri is assigned to the lizard family Iguanidae based on the Meckelian groove 16 and tooth morphology which closely approaches the morphol- ogy of several species of the iguanid lizard Sceloporus. Although similar in some respects, there are significant differences that serve to distinguish the two genera. The Meckelian groove, although restricted in Swainiguanoides, is open and not partially enclosed or in contact as in Recent species of Sceloporus. The intramandibular septum of Swainiguanoides is more pronounced than that of Sceloporus, and the V-shaped notch of the intramandibular septum is more developed in the latter genus. The tooth crowns are nearly identical in morphology to those in large individuals of Sceloporus poinsetti, but the teeth are taller and thinner. Etheridge (1964) noted that the teeth of Recent Sceloporus species are quite variable and offer few diag- nostic characters. In the dentaries of all sceloporine lizards the borders of the Meckelian groove are always in contact although never fused. An open Meckelian groove is probably a primitive character state in iguanines. The morphology of the teeth of Swainiguanoides milleri is remarkably similar to that of Recent Sceloporus, and in combination with other characters displayed in the dentary, suggests that Swainiguanoides milleri is related to the sceloporine group. Swainiguanoides milleri is significant in that it represents the oldest North American iguanid. The oldest 17 New World iguanid Pristiguana, reported by Estes and Price (1973) from the late Cretaceous of Brazil. cf. Swainiguanoides milleri Referred material: AMNH 12048 (Figure 10), medial part of left maxilla. Figure 10. cf. Swainiguanoides milleri (AMNH 12048), medial part of left maxilIa (lingual view). X 0. Remarks: This fragmentary specimen (Figure 10) is provisionally referred to Swainiguanoides milleri on the basis of tooth morphology. Suborder Scincomorpha Family Scincidae Genus Contogenys cf. Contogenys sloani Estes, 1969b Referred material: AMNH 12069 (Figure 11), posterior part of right maxilla bearing three teeth. 18 Figure 11. cf. Conto en 5 sloani (AMNH 12069), posterior part-3f—?IEH%_m§§III_. X 15. Remarks: This specimen is referred to Contogenys sloani based on the evidence of an expansion of the maxilla posteriorlaterally that indicates the probable presence of a triangular wedge reported by Estes (1969b) as well as the presence of strongly pleurodont teeth with squared-off tooth crowns. Family Xantusiidae Genus Paleoxantusia Paleoxantusia fera Hecht, 1956 Referred material: AMNH 12028, posterior part of right maxilla; AMNH 12036, posterior part of left dentary; AMNH 12038, posterior half of left dentary; AMNH 12039, anterior part of right maxilla; AMNH 12040, left dentary; AMNH 12041, posterior part of right dentary; AMNH 12049, medial part of left dentary; AMNH 12064 (Figure 12), nearly complete left dentary; AMNH 12071, anterior part of right dentary; AMNH 12072, anterior part of right dentary; AMNH 12073, posterior part of right dentary; AMNH 12074, 19 Figure 12. Paleoxantusia fera (AMNH 12064), left dentary ingua view). X posterior part of right dentary; AMNH 12075, left dentary; AMNH 12076, nearly complete right dentary; AMNH 12077, posterior part of right dentary; AMNH 12078, posterior part of right dentary; AMNH 12079, anterior part of right dentary; AMNH 12080, posterior part of right dentary; AMNH 12083 (Figure 13), posterior part of left maxilla; AMNH 14312, 4 teeth; AMNH 14313, medial part of right dentary; and AMNH 14314, posterior part of right maxilla. Figure 13. Paleoxantusia fera (AMNH 12083), posterior part 0 e t max1 1a. a. labial view; b. lingual view. X 12. Remarks: Although Paleoxantusia fera is represented by a number of specimens from Swain Quarry, little can be 20 said about variation in this species, owing largely to the fragmentary nature of most of the specimens. Most of the dentary material in which the teeth are not preserved are assigned to this species on the basis of the closed and fused Meckelian groove, lingual coronoid insertion surface and the anterior inferior alveolar foramen. Estes (1976) noted the common occurrence of Paleoxantusia fera in the Tongue River Formation and extended the range of this species from the middle Eocene (Hecht, 1956) down to the middle Paleocene (Torrejonian). The numerous specimens of this species from Swain Quarry indicate that Paleoxantusia fera was either a relatively common lizard during the middle Paleocene or that the ecologic and/or sedimentological conditions were such that P. fgga was selectively preserved. In addition, Estes (1976) noted previously unreported faint lateral crests on the tooth crowns of Paleoxantusia fera (Hecht, 1956, 1959). These crests are well developed on a number of the Swain Quarry specimens where the tooth crowns are preserved. cf. Paleoxantusia fera Referred material: AMNH 12043, medial part of right dentary; and AMNH 12059, medial part of right dentary. Remarks: The fragmentary naturecflfthese two specimens makes it impossible to refer them to Paleoxantusia fera with certainty, but are generally similar to the dentaries 21 of Paleoxantusia fera and are provisionally referred to this species. Family Xenosauridae Genus Exostinus Exostinus cf. E. lancensis Gilmore, 1928 Referred material: AMNH 14315 (Figure 14), medial part of right dentary; AMNH 14316, medial part of left dentary; AMNH 14317, medial part of left dentary; and AMNH 14318, anterior part of left dentary. Figure 14. Exostinus cf. E. lancensis (AMNH 14315), medial part of right dentary. X 10 Remarks: Based on characters used by Estes (1965, 1975 and 1976), these fragmentary specimens have a combi- nation of diagnostic characters that allow assignment to Exostinus lancensis rather than to E. rugosus or E. serratus. The labial side of the specimen is slightly roughened. The teeth curve lingually, taper to a point, possess a faint groove labially and are slightly recurved. A non-continuous pigmented traverse band is present at the 22 base of the crowns and at the top of the tooth shaft both lingually and labially. Estes (1964) reported on a number of specimens refer- able to this species from the late Cretaceous of wyoming and in a later paper (Estes, 1976), extended the range of this species upward through time, reporting E. lancensis from the middle Paleocene. Suborder Anguimorpha Family Anguidae Subfamily Odaxosaurinae, New Subfamily Type: Odaxosaurus Gilmore, 1928. Known distribution: Late Cretaceous through (?) late Paleocene of North America. Diagnosis: Differs from the Glyptosaurinae in the possession of non-tuberculate dermal armor. Differs from the other anguid subfamilies (Anguinae, Diploglossinae and Gerrhonotinae) in the possession of teeth with bulbous, expanded shafts and striated, blunt tooth crowns. Discussion: This subfamily is established for the genus Odaxosaurus which was previously designated subfamily incertae sedis by me (Sullivan, 1979). Odaxosaurus was originally included within the subfamily Anguinae by Meszoely (1970) in the belief that this genus was closely related to the Recent anguines and diploglossines. How- ever, I have shown (Sullivan, 1979) that Odaxosaurus 23 shares more characters with the glyptosaurines than with the anguines, thus necessitating the transfer of this genus to another subfamily. By excluding Odaxosaurus from both the Anguinae and the Glyptosaurinae, both of these sub- families retain their respective homogeneity. Many prob- lems concerning anguid origins may be resolved by a revi- sion of the fossil and Recent anguines. The Odaxosaurinae as herein defined, is established solely for the species Odaxosaurus piger. The late Paleocene species "Odaxosaurus" jepseni has been discussed by me (Sullivan, 1979:58) and is being transferred to a new genus by Jacques Gauthier of the University of California-Berkeley (personal commun., 1980). "Odaxosaurus" jepseni may represent a transitional morpho- type as it displays glyptosaurine tubercles on the dermal armor. The transitional dermal armor morphology seen in this species may not represent the inferred ancestral route from the Odaxsaurinae to the Glyptosaurinae via Xestops. I have stated (Sullivan, 1979, and in press) that there is evidence that the glyptosaurines were already established by the middle Paleocene, before the appearance of "Odaxosaurus" jepseni. Furthermore, the teeth of "Odaxosaurus" jepseni are different from Odaxosaurus piger and all other glyptosaurine lizards of both the Eocene and Oligocene. The teeth ". . . are pleurodont, stout, shafts compressed fore and aft with flattened sides, and closely 24 spaced in the jaw" (Gilmore, 1942:162) are markedly dif- ferent and thus probably represent a derived condition. This derived tooth morphology is distinctive and cannot be considered ancestral for the subfamily Glyptosaurinae. "Odaxosaurus" jepseni is here included within the Glyptosaurinae, but I consider this species as an early side branch of glyptosaurine evolution. Genus Odaxosaurus Odaxosaurus piger (Gilmore, 1928) Peltosaurus ? piger Gilmore, 1928, p. 136. Odaxosaurus obliquus Gilmore, 1928, p. 158. Pancelosaurus piger Meszoely, 1970, p. 105. Referred material: AMNH 12030, posterior part of right dentary; AMNH 12032, right dentary; AMNH 12033, ‘medial part of right dentary; AMNH 12035, posterior part of right dentary; AMNH 12060, medial part of left dentary; AMNH 12084, medial part of left dentary; AMNH 12085 (Figure 15), posterior part of left dentary; and AMNH 12086, posterior part of left maxilla; AMNH 14310 (Figure 16), l'medial part of left dentary. Remarks: These fragmentary specimens range in size from.6 mm (AMNH 12033) to 13 mm (AMNH 12085) and are quite variable as reported by Estes (1964). The apparent plasti- city in tooth morphology in Odaxosaurus piger ranges from the stout, squared off, blunt-crushing tooth type with 25 Figure 15. Odaxosaurus piger (AMNH 12085), posterior part of left dentary. X 5. striated crowns as seen inAmDH112085 (Figure 15) to that of a more gracile type with obliquely arranged teeth and less defined striations on the crowns as in AMNH 14310 (Figure 16). The variation in tooth morphology is due possibly in part to either: (1) representation of various ontogenetic stages of development or (2) the presence of more than one species. Meszoely et a1. (1978) indicated the former when Figure 16. Odaxosaurug piger (AMNH 14310), medial part of IEft dentary. a. labial view; b. lingual view. X 10. they synonymized Odaxosaurus obliquus (Gilmore, 1928 158) with Pancelosaurus (=Peltosaurus ?) piger (Gilmore, 1928: 136). Based on the Lance Creek specimens of the University of California-Berkeley' I have seen, morphotypes of 26 Odaxosaurus piger can be consistently distinguished inde- pendent of size and/or topographic location on the dentary or maxilla. Osteological and statistical reevaluation of Odaxosaurus piger may be in order to test the validity of the synonymy of Odaxosaurus obliquus with Odaxosaurus piger. These specimens are referred to Odaxosaurus piger based on size and morphology similar to specimens from the late Cretaceous Lance Formation. There appear to be no characters present that suggest a different species for these middle Paleocene specimens. Based on the non- abutting teeth, none of the specimens can be referred to "Odaxosaurus" jepseni. Odaxosaurus piger has been to date known from the late Cretaceous deposits through late Paleocene (Tiffanian) of North America (Estes, 1964, 1975 and 1976). Subfamily Glyptosaurinae Glyptosaurinae Indeterminate Referred material: AMNH 12031, posterior part of right maxilla; AMNH 12042, medial part of left dentary; AMNH 12044 (Figure 17), premaxilla; AMNH 12045, anterior part of left dentary; AMNH 12065, medial part of right dentary; AMNH 12070, anterior part of right maxilla; AMNH 27 Figure 17. Glyptosaurinae Indeterminate (AMNH 12044), premaxilla. a. labial view; b. lingual view. X 10. 12088 (Figure 18), booth bearing region of right pterygoid; and AMNH 12091, medial part of (?) right maxilla. Remarks: These fragmentary specimens (Figures 17 and 18) are referred to the anguid subfamily Glyptosaurinae on the basis of their large size and tooth morphology. A few Figure 18. Glyptosaurinae Indeterminate (AMNH 12088), right pterygoid (palatal view). X 10. 28 of these specimens (AMNH Nos. 12042, 12045 and 12091) may be referable to the Odaxosaurinae due to their smaller size, but these specimens are quite fragmentary. I have noted (Sullivan, 1979) that distinguishing genera and species based on tooth and osteoderm.morphology is impos- sible within the subfamily Glyptosaurinae and that the tooth morphology is very similar to that of the Odaxosaurinae. Subfamily Glyptosaurinae and/or Odaxosaurinae Indeterminate Referred material: AMNH 12089, 21 body osteoderms. Remarks: Three morphotypes of osteoderms are repre- sented in the material from Swain Quarry: (l) tubercular; (2) pit and ridge; and (3) combination pit and ridge/ tubercular. The osteoderms of the subfamily Glyptosaurinae are characterized by the presence of tubercles whereas those of the Odaxosaurinae retain the primitive pit and ridge morphology that is seen in other anguid lizards. A few of the osteoderms from Swain Quarry, as well as some from the older Puercan age deposits from the San Juan Basin, New Mexico (Sullivan, in press) show a combined pit and ridge/tubercular morphology similar, if not identical, to that as reported for "Odaxosaurus" jepseni. 29 Subfamily Anguinae Genus Machaerosaurus Machaerosaurus torrejonensis Gilmore, 1928 Referred material: AMNH 12047, medial part of left dentary; AMNH 12063 (Figure 19), posterior part of right maxilla; AMNH 12066, medial part of right dentary; AMNH 12068 (Figure 20), anterior part of right maxilla; AMNH 12087 (Figure 22), left frontal; AMNH 12094, medial part of left dentary; AMNH 12095, posterior part of right maxilla; AMNH 12097, anterior part of left maxilla; and AMNH 12099 (Figure 21), nearly complete right dentary. Remarks: Gilmore (1928) named Machaerosaurus torrejonensis based on an incomplete skull (AMNH 5184) from the Arroyo Torrejon, Nacimiento Formation (Torrejonian), San Juan Basis, New Mexico. No other species have been referred to this species prior to this study. Comparison Figure 19. Machaerosaurus torrejonensis (AMNH 12063), posterior part of the right maxilla (lingual view). X 15. 30 of the Swain Quarry specimens with the holotype indicate that this taxonomic assignment is unquestionable. The Swain Quarry lizards referable to Machaerosaurus torrejonensis comprise a significant percentage of the lizard fauna. The disarticulated dentaries and maxillae offer for the first time a lingual view of the teeth of Machaerosaurus torrejonensis. The teeth extend a little less than half their height above and below the parapet of the dentary and maxilla. The labial surfaces of the teeth are non-striated but the lingual surfaces are grooved. Two grooves appear on the posterior maxillary teeth, with the anterior groove being more pronounced than the posterior one (Figure 19) and with both grooves extending to the tooth base. The teeth in the anterior portion of the maxilla (Figure 20) as well as the teeth of the dentary Figure 20. Machaerosaurus torrejonensis (AMNH 12068), anterior part of right maxilla. a. labial View; b. lingual view. X 10. (Figure 21) have only the anterior groove. This groove ends approximately half way down the tooth shaft. All 31 Figure 21. Machaerosaurus torrejonensis (AMNH 12099), right dentary. a. labial View; b. lingual view. X 8. teeth are laterally compressed and slightly recurved in both the dentary and maxilla as seen in the holotype (AMNH 5184) recently redescribed by Sullivan (in press). A left frontal, AMNH 12087 (Figure 22) is identical to the preserved edge of the frontal of the holotype (AMNH 5184), in size, shape and dermal armor sculpturing. Furthermore, this specimen indicates that the frontals were paired rather than fused. The frontal is significantly different from Odaxosaurus piger and other genera belong to the Anguinae, but compares closely to frontal material, shown to me by Richard Estes that has been tentatively referred to "Odaxosaurus" jepseni. 32 Figure 22. Machaerosaurus torrejonensis (AMNH 12087), left frontal (anterior direction is up). X 10. Recently, Meszoely et a1. (1978) reported the anguine lizard "Pancelosaurus" (=Odaxosaurus) pawneensis of the early and middle Oligocene of North America should be transferred to the genus Machaerosaurus. I suggested (Sullivan, in press) that the "pawneensis form.represents an undescribed genus that appears to be related to North American Ophisaurus; thus, Machaerosaurus is represented by only one species, E. torrejonesis. Machaerosaurus torrejonensis is still known only from middle Paleocene (Torrejonian) deposits of North.America. 33 cf. Machaerosaurus torrejonensis Referred material: AMNH 12034, posterior part of left maxilla; AMNH 12050, greater part of left dentary; AMNH 12051, posterior part of right dentary; AMNH 12055, medial part of left dentary; and AMNH 12092 (Figure 23), posterior part of right dentary. Figure 23. cf. Machaerosaurus torrejonensis (AMNH 12092), posterior part of right dentary (lingual view). X 10. Remarks: The above specimens are designated cf. Machaerosaurus torrejonensis based primarily on size and shape of the dentaries or maxilla and in the case of AMNH 12055, an anterior groove that appears on the upper most part of the posterior most tooth. All of these specimens are missing the diagnostic tooth crowns from breakage or from wear as seen in AMNH 12092 (Figure 23). Family Anguidae Indeterminate Referred material: AMNH 12008 (Figure 24), proximal end of left ramus; AMNH 12029, posterior part of left 34 Figure 24. Anguidae Indeterminate (AMNH 12008), articular end of left ramus (lingual View). 8. maxilla; AMNH 12037 (Figure 25), medial part of right dentary; AMNH 12054, medial part of right dentary; AMNH 12062 (Figure 26), greater part of right dentary; AMNH 12090, medial part of right dentary; AMNH 12096, medial part of left dentary; AMNH 12098, posterior part of right dentary; AMNH 14319, anterior part of right dentary; AMNH 14320, medial part of right dentary; and AMNH 14321, greater part of left dentary. Figure 25. Anguidae Indeterminate (AMNH 12037), medial part of right dentary (lingual view). X 12. Remarks: The fragmentary nature of the above speci- mens and those below questionably identified as indeter- minate anguids make them impossible to place with certainty 35 Figure 26. Anguidae Indeterminate (AMNH 12062), right dentary (lingual view). X 12. in any anguid genus or subfamily. However, I believe that much of this material considered here may represent the subfamily Anguinae and the genus Machaerosaurus. Most of this material is assigned to the family Anguidae on the basis of an open, free intramandibulur septa, gracile morphology and boat-shaped dentaries. cf. Anguidae Referred material: AMNH 12052, medial part of left dentary; AMNH 12053, anterior part of left dentary; AMNH 12056, medial part of left dentary; AMNH 12057, anterior part of right dentary; AMNH 12058, medial part of left dentary; and AMNH 12093, anterior part of right dentary. Remarks: These specimens are so fragmentary that familial assignment is uncertain, but are provisionally referred to the Anguidae based on size and shape. 36 Family Parasaniwidae cf. Provaranosaurus sp. Referred material: AMNH 14306, medial part of left dentary; AMNH 14307, medial part of left dentary; and AMNH 12309 (Figure 27), medial part of right dentary. Figure 27. cf. Provaranosaurus sp. (AMNH 14309), medial part—3f_fighE—dgfifgry (lingual view). 0. Remarks: The fragmentary nature of these specimens makes it difficult to establish their taxonomic position. All three specimens lack the diagnostic teeth, but the basal outlines of the teeth show that they are suboval in cross-section. The intramandibular septum is smoothly fused, and thus, with thetoothoutlines, these specimens are provisionally referred to Provaranosaurus sp. Estes (1975) noted that Provaranosaurus acutus was known to occur only in the Princeton Quarry local fauna (late Paleocene-Tiffanian). Material designated cf. Provaranosaurus sp. is known from the earlier middle Paleocene (Torrejonian) Medicine Rock local fauna (Estes, 1976). The Swain Quarry local fauna occurrence of cf. 37 Provaranosaurus sp. further establishes this lizard as a middle Paleocene form. Indeterminate Lacertilia Referred material: AMNH 12041, ventral part of basicranium; AMNH 12046, posterior part of left dentary; AMNH 14322, anterior part of left dentary; AMNH 14323, fragment of (?) right dentary; AMNH 14324, medial fragment of right dentary; AMNH 14325, medial part of right dentary; and AMNH 14326, medial part of left dentary. Remarks: The fragmentary nature of the above speci- mens makes reliable familial and general assignment impos- sible. Order Serpentes Family Boidae Subfamily Erycinae Genus Helagras Helagras prisciformis Cope, 1883 Referred material: AMNH 12025, trunk vertebra; AMNH 12026, trunk vertebra; and AMNH 12027 (Figure 28), trunk vertebra. Remarks: Cope (1883) named Helagras prisciformis based on two articulated trunk vertebrae from the Puercan (early Paleocene) horizon of the Nacimiento Formation of the San Juan Basin, New Mexico. Gilmore (1938) redescribed 38 Figure 28. Helagras prisciformis (AMNH 12027), trunk vertebra. a. dorsal view; b. axial view. X 6 the type specimen as well as referred material of E. prisciformis, and noted the boiid affinites, but hesitantly included this species within his "Serpentes of unknown family reference." Hoffstetter and Rage (1972:111) included Helagras within the Boidae, and furthermore within the subfamily Erycinae. Holman (1979), in his review of North American Tertiary snakes, suggested that the sub- familial designation of the North American species be con- sidered tentative, pending a revision of the New World fossil snakes. The three snake vertebrae from Swain Quarry are referred to Helagras prisciformis on the basis of the presence and/or evidence of a "short, thickened, tuberous- like neural spine" as described by Gilmore (1938 83). Helagras princiformis is the only Paleocene North American snake known and has only been found in Puercan and Torrejonian (early and middle Paleocene) deposits. Its 39 occurrence in Swain Quarry extends its paleogeographic range from its type locality in northwest New Mexico to southcentral Wyoming. COMPARISON OF LATE CRETACEOUS AND PALEOCENE LOWER VERTEBRATE FAUNAS OF THE ROCKY MOUNTAIN REGION, NORTH AMERICA Of the three major North American Paleocene lower vertebrate assemblages known (Princeton Quarry local fauna of Estes, 1975; Medicine Rocks Local fauna of Estes, 1976; and Swain Quarry local fauna, this paper), the Swain Quarry local fauna is the largest in terms of numbers of specimens, although its taxonomic diversity is comparable to the above faunas reported by Estes. In this section the Swain Quarry lower vertebrate local fauna is compared to pre- viously reported local faunas of similar age and location in order to provide information on depositional-paleo- environmental controls, evolutionary trends, endemic species and general paleobiogeographical patterns of parti- cular taxonomic groups. The Swain Quarry lower vertebrate microfauna is domi- nated by reptiles, primarily lizards, and by amphibians (urodeles). Percentages based on minimum.number of individuals (MNI) show that the fish comprise 4.8% of the ventire microfauna, amphibians, 24%, and reptiles 71% (Table 1). Among the reptiles the lizards comprise 67%, crocodilians 1.5%, and the snakes 1.5%. The anguid lizards 40 41 TABLE 1 LIST OF MINIMUM NUMBERS OF INDIVIDUALS (MNI) AND PERCENTAGES OF HIGHER TAXA FROM SWAIN QUARRY Number of % of Higher Taxa Taxa Specimens MNI Based on MNI Amia fragosa 3 2 Fish = 4.8% 'Toleostei Insertae Sedis l l Scapherpeton tectum ll 8 -------------------- cf. Opisthotriton kayi 5 3 ?§£2§:i22§ = 24% Habrosaurus dilatus 7 4 Crocodilia Indeterminate l l 5-6;3235111;;;—;-1:§i Swainiguanoides milleri 3 2 E -------------------- cf. Contogenys sloani l 1 E _Paleoxantusia fera 23 12 i Exostinus cf. E. lancensis 4 3 f Odaxosaurus piger 9 4'; Glyptosaurinae 8 3 3 iLizards = 67% Indeterminate :: ‘Machaerosaurus l4 4 5‘ torrejonens1s fi Anguidae Indeterminate l7 9 5 cf. Provaranosaurus sp. 3 2 g Lacertilia Indeterminate 7 3 E Helagras prisciformis 3 1 §--SnaRes-;-1:5% ----- Total 120 63 42 comprise 47% of the lizard fauna and 32% of the entire sample of the Swain Quarry lower vertebrate microfauna. The above percentages represent an indication of the relative abundance of the lower vertebrates from this quarry which Estes reports (personal commun., 1980) is con- sistent with other lower vertebrate Paleocene microfaunas from quarries that yield a large number of mammalian fos— sils. The apparent rarity of the lower vertebrates from Swain Quarry is probably due to depositional factors as the meticulous sampling efforts of the AMNH field parties should have eliminated any bias in the recovery of these specimens (Rigby, personal commun., 1979). Comparison of the Swain Quarry lower vertebrate micro- fauna to other North American faunas of the late Cretaceous and early Paleocene can be made with only a few others. Only two main late Cretaceous lower vertebrate faunas from the general region of Swain Quarry have been described by Estes (1964), Estes et a1. (1969), and Estes and Berberian (1970). Only two major studies on North American lower vertebrate microfaunas from the Paleocene age have been made (Estes, 1975, 1976) and the taxa of these two studies are compared with that of Swain Quarry (Table 2). Most of our knowledge concerning the faunae of this time period comes from these studies and from some isolated descriptions by Gilmore (1928, 1942). Contri- butions concerning specific taxonomic groups of lizards 43 TABLE 2 OCCURRENCES OF LOWER VERTEBRATE TAXA FROM THE THREE MAJOR PALEOCENE LOWER VERTEBRATE LOCALITIES OF NORTH AMERICA N S- n “a a 2' ‘3" O a ‘U D '0 O H TAXA Fort Union Foraetion Big Horn Basin 0' Foraetion 8.8. Montana Tongue River Fort Union Foraation Swain Quarry Consents on the Occurrence of Taxa in Swain Quarry Dasyatidae indeterminate cf. égizenser sp. cf. Palaeopsephurus sp. 11-29392 1mm Legisosteus occidentalis cf. Palaeolabrus aontansnsis Teleostei incertae sedis fish sparsely represented Scaphegpeton tectum 921sthotriton 551; Lisserpeton bairdi Habrosaurus dilatus ghiuna e seni ”XX” xxxxxxxx ’1 urodeles moderately represented lorhinophrynus sp. cf. Scotiophrzge sp. Discoglossidae. undescribed gen. 5 sp. Anura incertae sedis indeterminate frogs absent Platobaena bairdi Eggpsemys victa Indeterminate Baenidae cf. Plastomenus sp. Ptzchogaster sp. xxxx ”’1” turtles not studied EMIOIOUWI OP . eosuchians absent Leidyosuchus sp. Alloggathosauchus sp. Crocodylidae indeterminate Alligatorinae. unidentified gen. 6 sp. crocodilians largely not studied Swainiguanoides milleri Contogenys sloani Paleoxantusia {era Exostinus langensis Exostinus cf. lancensis Exostinus rugosus Odaxosaurus piger cf. Gerrhonotus sp. (7-Hacheerosaurus) Glyptosaurinae indeterminate Hechaerosaurus torrejonensis Provaranosaurus acutus cf. Provaranosaurus sp. X lizards relatively abundant Oligodontosaurus gloain'ensis cf. Oligodontosaurus sp. Ihineuridae. unidentified gen. 5 sp. anphisbaenids absent Conioghis sp. cf— was; up. Helagras prisciformis snakes aoderately represented 44 from the early Tertiary are found in more comprehensive works by Meszoely (1970) and Sullivan (1979). Table 3 summarizes the time-stratigraphic occurrences of the Swain Quarry lower vertebrates based on the above papers. A brief discussion of the compared faunas is presented below. Because of the incomplete sample size, paleo- ecological analyses proposed by Shotwell (1955) and used by Estes and Berberian (1970) for lower vertebrates cannot be used for the study of the Swain Quarry lower vertebrate microfauna. Any interpretation of the general paleoecology must rely heavily on the mammalian fossils, but may some- times be augmented by the lower vertebrates. Fish Amia fragosa is indicative of a fresh water habitat, usually stagnant and/or lakes, ponds, or sluggish streams (Estes, 1964). The presence of this fish in the Swain Quarry suggests a drainage situation similar to the present day Gulf Coast of the Mississippi delta. Amphibians The urodeles Habrosaurus dilatus, Scapherpeton tectum and cf. Opisthotriton kayi also suggest a freshwater environment. Trends in their relative abundance from sites from the mid-Campanian through the late Paleocene were reviewed by Estes (1976). 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