THE PEARCE­SELLARDS Series NUMBER 33 EARLY TERTIARY VERTEBRATE FAUNAS TRANS-PECOS TEXAS: AMYNODONTIDAE John Andrew Wilson and Judith A. Schiebout June 15, 1981 Texas Memorial Museum/2400 Trinity/Austin, Texas 78705 William G. Reeder, Director The Pearce-Sellards Series is an occasional, miscellaneous series of brief reports of museum and museum-associated field investigationsand other research. All manuscripts are subjected to extramural peerreview before being accepted. The series title commemorates the first two directors of the Texas Memorial Museum, both now deceased: Dr. J. E. Pearce and Dr. E. H. Sellards, professors of anthropology and geology, respectively, at The University of Texas at Austin. Acomplete pricelistofPearce-Sellardspapers andotherbulletinsand miscellaneous publications of the museum will be sent upon request. —Jane Sullivan, Editor CONTENTS Page ABSTRACT 1 INTRODUCTION 1 Previous Work 1 Abbreviations 3 Acknowledgments 3 SYSTEMATIC PALEONTOLOGY 5 GenusAmynodon 5 Amynodon advenus 11 Amynodontopsis bodei 42 Metamynodon mckinneyi 48 Metamynodon cf. M. chadronensis 54 SUMMARY AND CONCLUSIONS 58 LITERATURE CITED 60 TABLES Page Table 1. Measurements ofupper and lower teeth of Amynodon advenus. Whistler Squat l.f 20 2. Measurements of upper and lower deciduous dentition ofAmynodon advenus, Whistler Squat 1.f.; Amynodontopsisbodei, Skylinel.f.\Metamynodon chadronensis, Porvenir l.f 23 3. Measurements ofupper and lower dentitions ofvarious amynodonts from deposits of earlyUintan age 30 4. Measurements ofskulls and lower jawsofAmynodon advenus 32 5. Statistical data for upper and lower teeth of Amynodon advenus, Whistler Squat l.f. and northern localities 34 6. Measurements and statistical data for astragalusofAmynodonadvenus,WhistlerSquatl.f 36 7.Statistical dataforastragalusofCeratotherium praecox 37 8. Measurements and statistical data for M M 3 2, ofAmynodon advenus and statistical datafor M M 3 of Ceratotherium praecox 38 2, 9. Statistical data for M 2 and M 3 of Trigonias 39 10. Statistical data forHippopotamus amphibius 39 11.Measurementsofpostcranial bonesofAmynodonadvenus, A. intermedius, and Metamynodon planifrons 40 12. Measurements ofupper teeth ofamynodontidsoflate Eocene and earliest Oligocene 46 13. Measurements oflower teethofamynodontidsoflate Eocene and earliestOligocene 46 14. Observed ranges ofmeasurements ofupperteeth ofamynodontids in stratigraphic order 56 15. Observedrangesofmeasurementsoflower teeth of amynodontids in stratigraphic order 57 FIGURES Page Figure 1.Stratigraphicsectionandindextostratigraphic position of amynodontids in West Texas 12 2. Amynodon advenus, lateral view of skull 13 3. A. advenus, dorsal view of skull 14 4. A. advenus, lateral view of male and female upper canines 15 5. Lower canines ofA. advenus, Metamynodonmckinneyi n. sp., and M. chadronensis 17 6. A. advenus, lateral and occlusal view ofupperdentition 18 7.A. advenus, lateralviewoflowerjaw 19 8. A. advenus, occlusal and lateral views oflowerdentition 22 9. A. advenus, ventral view of juvenile skull 24 10. A. advenus, lateral view of juvenile skull 25 11. A. advenus, dorsal view of juvenile skull 26 12.A.advenus,lateralviewofjuvenilelowerjaw 27 13. A. advenus, ventral view of basicranium 29 14. Amynodontopsis bodei, lateral view oflowerjaw 43 15.A. bodei, occlusal and lateralviews oflower dentition 44 16. A. bodei, lateral and occlusal views of upper deciduous dentition 45 17.Metamynodon mckinneyi n. sp., type,lateralviewoflowerjaw 49 18.M. mckinneyi n. sp., dorsal view of symphysis 49 19. M. mckinneyi n. sp., lateral view of symphysis 50 20. M. mckinneyi n. sp., type, occlusal and lateral views of lower dentition 51 21. Metamynodon chadronensis,lateral view of skull 53 22. M. chadronensis, dorsal view of skull 54 23. M. chadronensis, ventral view of skull 54 24. M. chadronensis, lateral view of lower jaw 55 25. M. chadronensis, dorsal view of lower jaw 55 Figure 1. Diagrammatic stratigraphic section of the Buck Hill Group, Devil’s Graveyard-Bandera Mesa area, Brewster and Presidio Counties, Texas, to show approximate relative thickness and stratigraphic position of fossil localities, local faunas and North American land mammal ages. Devil’s Graveyard Formation and Bandera Mesa Member are manu­script names reserved by Geologic Names Committee, U.S. Geological Survey. Radio­metric dates (in million of years) are from McDowell (1979) except the following, which are previously unpublished dates from Geochron Laboratories: 52.0 ± 2.4 m.y. (wholerock basalt, above basal Tertiary conglomerate and within variegated beds); 41.7 ± 1.6 m.y. (biotite-bearing ash, just below Skyline channel); 32.2 ±1.5 m.y. (whole rock basalt,lowest basalt Bandera Mesa). The number in parentheses following the date signifies the number of samples. Letters refer to stratigraphic position of one or more fossil localities. Fossil localities referred to in this paper are: B. 41372, Whistler Squat quarry; 41576,southwest of wax camp; 41747, Boneanza; E. 41723, Titanothere hill; 41549, Margaret’sbonebed. G. 41715, North Fork of the Alamo de Cesario;4l66B, east side Devil’s Backbone. H. 41853, Horseshoe stone coral, Cotter channels. Stratigraphic section compiled byJames B. and Margaret S. Stevens, Lamar University, Beaumont Texas. EARLY TERTIARY VERTEBRATE FAUNAS, TRANS-PECOS TEXAS: Amynodontidae John Andrew Wilson1 and Judith A. Schiebout2 ABSTRACT Skulls, lower jaws and limb bones, identified as Amynodon advenus, were recovered from a quarry and from other localities at the same stratigraphic level in deposits of early Uintan age that contain the Whistler Squat local fauna in West Texas. Forms with large canines and long post-canine diastemas are identified as males, whereas forms with smaller canines and shorter diastemas are identified as females. A new spe­cies of Metamynodon from the Myton Uintan is based on a massive lower jaw. Amyno­dontopsis bodei is found in the Skyline and Cotter channels of latest Eocene and earli­est Oligocene. Metamynodon chadronensis from the Porvenir local fauna of the Vieja area is described. INTRODUCTION Amynodont remains have been found in the upper Eocene deposits of the Agua Fria area and in the lower Oligocene deposits of the Vieja area. A generalized stratigraphic section of the Agua Fria area is given in figure 1. The largest number of specimens was recovered from the lower part of the Pruett Em. in the Agua Fria area. This sample, although not as large as desired, makesitpossibletoassesstheamountofvariationinanamynodontpopulation at a small area over a short interval of time. Most of the mate­rial came from a single quarry located approximately 600 feet (183 m) east of Whistler Squat on the Agua Fria Quadrangle, Brewster County, Texas (Moon, 1953). Smaller, but important, samples occurred higherin the Pruett Em. and in the lower part of the section in the Porvenir area. The location of the Vieja area and the stratigraphic occurrence of the meta­mynodonts are given in Wilson (1977b, tables 1, 2, 3, 4, 6). PREVIOUS WORK This is one of several papers that deal primarily with the early Tertiarystratigraphy and the fossil vertebrate faunas of Trans-Pecos, Texas. They are: Wilson (1966), Harris (1967), Hoffer and Wilson (1967), Wilson et al. (1968), Harris and Wood (1969), Wilson (1971a, 1971b), Wood (1973, 1974), Schiebout (1974), Wilson (1974), Szalay and Wilson (1976), Wilson and Szalay (1976), Schiebout (1977b), Wilson (1977a, 1977b). The Whistler Squat locality was first mentioned by Wilson (1972), and the fauna is not yet completely described. Wood (1973) described the rodents and referred to the assemblage as the Whistler Squat local fauna. 1 Professor Emeritus, Department of Geological Sciences, The University of Texas at Austin; Research Associate, Texas Memorial Museum. 2 AssociateProfessor, DepartmentofGeology,LouisianaStateUniversity,Baton Rouge. He believed on the basis of the rodents that the local fauna was of Bridger­ian age. Wilson (1974), on the basis of the presence of Leptoreodon and the amynodont, herein identified as Amynodon advenus, believes the age to be early Uintan. A succession of faunas in superposition is now known in the AguaFria-Green Valley area as a result of further field work, particularly that of Dr. James B. Stevens and Margaret S. Stevens. The stratigraphy of the area and the position of the more important localities are in manuscript (J.A. Wilson, J.B. Stevens, & M.S. Stevens). The superpositional order and age ofthe local faunas are given here, for convenience, in figure 1. The manuscript names, Devil’s Graveyard Formation and Bandera Mesa Member (fig. 1), will be proposed by J.B. and M.S. Stevens and J.A. Wilson and have been reserved by the Committee on Geologic Names of the United States Geological Survey. The name Pruett Formation,however, will be used in the text of this paper. It will be abandoned in the later manuscript because the top of the Pruett Fm. was defined as the base of the Crossen Trachyte by Goldich and Elms (1949) and the Crossen Trachyte does not extend as far south as the Agua Fria or Tascotal Mesa Quadrangles. The Whistler Squat quarry rested on a calcareous tuff (fig. 1, B) that was dated by Fred W. McDowell of the Department of Geological Sciences atTheUniversityofTexasatAustinas45.8± 1.1and48.6±1.3(McDowell,1979). Another date of 42.9 ± 0.9 is from a micaceous tuff associated with the first clinoptilolite channel above the stratigraphic level of the quarry. This would place the quarry in rocks of early Uintan or Wagon-hound age. The latest occurrence of amynodontids in Texas is in the Vieja area where Metamynodon chadronensis occurs in the Chambers Tuff which is bracketed by dates of 38.6 and 36.8 (Wilson, 1977b and McDowell, 1979),whereas M. planifrons extends to the middle Oligocene in South Dakota. Metamynodon mckinneyi n. sp. and Amynodontopsis bodei lie in between, with the former closer to 42.9 and the latter closer to 38.6. A skull of Sthenodectes from the Titanothere Hill locality (fig. 1, E) was previously referred by Wilson (1977a) to the Whistler Squat l.f. New faunal and stratigraphic information necessitated a new local fauna, the Serendipity l.f. above the Whistler Squat l.f. and below the Skyline l.f. Material from the Titanothere Hill locality is included in the Serendipity l.f. Tooth nomenclature is after Osborn but with no implication for originof the cusp. Measurements of the upper cheek teeth are the greatest lengthalong the ectoloph and the greatest width along the protoloph and metaloph.Lower cheek teeth were measured along greatest length and width. All measurements are in millimeters. Specimen numbers without prefixes belong to TMM; such numbers preceded by a hyphen are abbreviated, and include the five digit localitynumber preceding, e.g., 41372-1, -2. Detailed descriptions of localities are on file at the Vertebrate Paleontology Laboratory, Texas Memorial Museum, The University ofTexas at Austin. ABBREVIATIONS @ measurement approximatealv alveolus AMNH AmericanMuseumofNaturalHistory,NewYork AW width across protolophCIT Carnegie Institute of Technology, Pasadena, CA CM Carnegie Museum, Pittsburg, PA DW distal width est estimate FMNH FieldMuseumofNaturalHistory,Chicago,IF frag fragmentL anteroposterior lengthLACM(CIT) Los Angeles County Museum, California Institute of Technology Collection l.f. local fauna loc. localityM mean OR observed rangePU Princeton University, Princeton, NJ PW width across metalophPW proximal width of leg bone o standard deviation SDSM South Dakota School ofMines and Technology, Rapid CityTMM Texas Memorial Museum, The University ofTexas at Austin USNM United States National Museum V coefficient of variation expressed in percent W width YPM Yale Peabody Museum, New Haven, CN ACKNOWLEDGMENTS The Geology Foundation, the Owen-Coates Fund of the Geology Foundation of the Department of Geological Sciences, the University Research Institute, and the Vertebrate Paleontology Laboratory, Texas Memorial Museum of The University of Texas at Austin, have supported the field work, the laboratorypreparation, and inpart, thecost ofpublication.We are especially grateful to Dr. William D. Turnbull and Dr. Rainer Zangerl of the Field Museum of Natural History, Chicago, for the loan of material, information, and photographs concerning metamynodont material in their collection. We acknowledge and express our gratitude for courtesies to Dr. Donald Baird, Earl Manning, Dr. J.H. Ostrom, Dr. D.E. Savage and W.P. Wall. Dr. Ernest L. Lundelius and Melissa Winans were especially help­ ful concerning statistics. Dr. James B. Stevens and Margaret S. Stevens work­ed out the stratigraphic sequence in the Agua Fria area, and Mrs. Stevens and Robert H. Rainey collected much of the material herein described. The Whistler Squat Quarry was discovered by Robert H. Rainey and John A. Wilson in 1970 and was extensively worked in 1971. Members of the 1971 field party were Dr. Anne Forsten, Richard P. McCulloch, Robert H. Rainey, Margaret S. Stevens, Sally Rogers Scanlon and Dr. John A. Wilson. Mr. and Mrs. Billy Pat McKinney, the lessees, and J.H. Burton, Sid Burton and Macon Richmond, owners of the Agua Fria Ranch, provided invaluable assistance to field parties. The upper reaches of the Alamo de Cesario extend onto the ranch of Dr. Walter W. Dalquest of Midwestern University, who generously permitted us access to his land. Clegg Fowlkes of Marfa, Texas has been most helpful in giving us access to his ranches in the Green Valley area. This publication is a contribution of the Vertebrate Paleontology Faboratory, Texas Memorial Museum, The University of Texas at Austin. SYSTEMATIC PALEONTOLOGY Order Perissodactyla Owen 1848 Suborder Ceratomorpha Wood 1937 Superfamily Rhinocerotoidea Gill 1872 Family Amynodontidae Scott & Osbom 1883 Genus Amynodon Marsh 1877 Synonym Orthocynodon Scott & Osbom 1882 Type species Amynodon advenus (Diceratherium advenum) (Marsh, 1875) Included species; Amynodon advenus, A. reedi. Amynodontids have lent their names to prominent stratigraphic marker beds in the Eocene and Oligocene, the Amynodon sandstone of the Uinta Basin and the Metamynodon channels of the South Dakota Badlands. Yet, in spite of the relative frequency with which one encounters the name Amynodon in the paleontologic literature relating to the western interior of the United States, there has been published relatively little descriptivemorphology since Osbom (1895). Furthermore, no comprehensive studyof the family has been published3 since Gromova (1954), but she dealtpri­marily with Mongolian amynodontids. Four North American species of Amynodon have been described from the Rocky Mountain area and one from California. The earliest was A. advenus based on an M YPM 1 1763, first described by Marsh (1875) 3, as Diceratherium advenum. Two years later Marsh (1877) described the new genus Amynodon and referred to “a nearly perfect skull and various other ... . remains from the Uinta, or Diplacodon beds . . .” Marsh also stated, “The type species is Amynodon advenus Marsh, which was provisionallyreferred to the genus Diceratherium when first described.” In 1833, Scott and Osborn named the family Amynodontidae and in­cluded within it the genera Amynodon and Orthocynodon. In the same paper, they described 0. antiquus which was based on a lower jaw and the posterior portion of a skull (PU 10047), without the snout anterior to P 3 Scott and Osborn (1833, p. 9) used the structure of the third upper . premolar to distinguish Orthocynodon from Amynodon, but in 1887 theyreferred to Orthocynodon as a probable synonym ofAmynodon and in 1890 Osbom (1890, p. 507) was again doubtful that A. advenus and O. antiquus were generically distinct. He pointed out that, “A second examination of 3 Mr. William P. Wall of the University of Massachusetts is currently undertaking a study of the family Amynodontidae. type specimen recently made brings out several important diagnostic charac­ters The type of A. antiquus is still found to resemble that of A. .... advenus closely, with the important exception that there are four lower pre­molars instead of three, the first lower premolar being fully functional and bifanged; the first upper premolar is missing.” It must be pointed out, how­ever, that the type of A. antiquus, PU 10047, is figured in Scott and Osborn (1833, pi. 5). In the side view of the lower jaw,M 3 and a section completely through the lower jaw are shown as restored but on the occlusal view the M 3 is not represented. In the side view of the skull, the nasal region and P 1 and P 2 are shown as restored. Neither of these restored teeth is shown on theocclusalviewoftheupperdentition. EarlManning(personalcommunica­tion, October 5, 1978), of the American Museum of Natural History, who had the type specimen from Princeton University on loan, very kindly con­firmed my suspicion that the M 3 in the type lower jaw, PU 10047, is restored and that “there is no evidence of a tooth posterior to the last tooth in the occlusal figure. There is no bone present behind the last tooth in the figured rt. ramus.” This changes the interpretation of the lower dental formula of A. antiquustoP2-P4,Mj-M3 whichisthesame asthatofotherearlyUintan North American amynodonts. ThetypespecimenofA.antiquuswascollectedintheBitterCreek coun­try of the Washakie Basin of Wyoming. Osborn (1929, fig. 62) showed Amynodon antiquus type as coming from the approximate zonal level of Adobe Town. The Adobe Town Member of the Washakie Formation was described by Roehler (1973) and correlated by him with the Wagonhound Member of the Uinta Formation of the Uinta Basin. Osbom (1890, p. 506) said that, “There are now three skulls known which may be referred to three species. First, the type Amynodon advenus from the Uinta beds; second, the type ofA. (Orthocynodon) antiquus, nobis,from the Washakie beds; third, the type of A. intermedins spec, nov., from the Uinta.” Osborn (1890) and Scott and Osborn (1887) were wrong in referring to a skull as the type ofA. advenus. The type ofA. advenus is the M 3 described by Marsh (1875). However, Osbom (1890) revised Marsh’s very brief description (1877) of the referred skull of A. advenus. A. inter­medins was distinguished by Osborn (1890, p. 507) from A. advenus and A. antiquus by its much larger size, by the procumbent canines and by re­tention of a single-fanged first upper premolar. Five years later Osborn (1895, p. 95) modified his description ofA. intermedins somewhat, based on more material, none of which, to our knowledge, has ever been figured.His diagnosis as of 1895read: “Dentition: 13,I3 C}, DP4, M 3. Upper canines suboval in section, inclined forwards. Four ,deciduous premolars in both jaws. Four permanent premolars in the upper jaw? Tower canines erect,triangular.” In the same paper Osborn (1895, p. 75) listed the succession of speciesin the Uinta Basin. Amynodon, AMNH 1878, is listed as having been found in Horizon A—Tower Level; AMNH 1932, 1936, and 1830, also identified as Amynodon, were from Horizon B—Middle Level;and Amynodon intermedins, AMNH 1933, was from Horizon C—Upper Level. This terminology of the stratigraphic units was changed by Osborn (1929, p. 91) and summarized in Wood et al. (1941) and later by Roehler (1973). Osborn (1929) in his valu­able section on the stratigraphy of the intermontanebasins showed the distri­bution of Amynodon as follows. For the Washakie Basin (p. 89): “Amyno­don antiquus, type. (First of the amynodonts [aquatic rhinoceroses].)”Washakie B1 and B2 (Eobasileus-Dolichorhinus zone). And on p. 90, figure62, he showed Amynodon antiquus type as occurring at the level ofAdobe Town. For the Uinta Basin, Osbom (1929, p. 92) clarified the stratigraphic terms as follows: Uinta B2 of Peterson and Osborn; Dolichorhinus cornutus zone of Osborn (1895. 98). Amynodon beds of Riggs (1912.1, p. 22).Coarse brownish dacite tuffs and sandstones, capped at the summit by the ‘Amynodon sandstone’ immediately underlying Uinta C,” and in this unit he stated that Amynodon intermedins was abundant. On the following page(Osborn, 1929, p. 93) A. intermedins is shown as having been found in the “Amynodon sandstone” at the top of Uinta B2 and also in Uinta Cl “Amynodon skel. Am Mus. No. 1933.” Moreinformation concerningA. intermedinswas givenbyColbert(1938)in his description of Paramynodon birmanicus. The former, as the largestspecies of North American Eocene amynodonts, was compared to the Bur­mese material. In addition Colbert (1938) very carefully analyzed those characters used by Pilgrim (1925) and Pilgrim and Cotter (1915) to distin­guish P. birmanicus from P. cotteri. Colbert (1938) came to the tentative conclusion that the differences between the two species are due to sexual dimorphism within a single population. Our study of the Texas Eocene amy­nodonts brings us to a similar conclusion. In 1921 Troxell describedA. erectus. Troxell made the skull, mentioned by Marsh (1877) to supplement the description ofA. advenus, the type of A. erectus. Troxell separated A. erectus from A. advenus on minor differ­ences in size, a stronger cingulum, and a deeper postsinus ofthe third uppermolars. In addition Troxell (1921) stated that “A. antiquus may be distinct­ly separated from the others, perhaps subgenerically by the presence of both upper and lower functional first premolars, and by a marked difference in the general proportions of the teeth. The new species, A. erectus, is small and primitive, and in this respect approaches A. antiquus, but it has lost all trace of the first premolars and is of a later geological horizon.” The onlyfigures of A. antiquus that we can find are those of the type published byScott and Osborn (1883, pi. V). The dentition of the type specimen, PU 10047, as previously mentioned, can be interpreted as having only three premolars. The upper dentition of the type has only P3 and 4 preserved.There is no evidence for a first premolar, upper or lower, in A. antiquus. Peterson (1919) discussed material of the genus Amynodon collected in the Uinta Basin but did not give locality or stratigraphic information. He (Peterson, 1919, p. 130) said: “This genus is represented by a number of individuals. The material has a considerable range in size and undoubtedly represents two or probably three species. Unfortunately the fragmentary condition of the greater number of the specimens does not admit of an accurate identification. The smaller individuals therefore provision- are ally placed in Amynodon advenum (Marsh) while the larger are referred to Amynodon intermedins Osborn.” Wood, Seton, and Hares (1936) listed A. advenus from upper Eocene beds on the north side of the Wind River Basin in the Badwater area. The Badwater fauna (except that from Carnegie Museum locality 20, Krishtalka andSetoguchi,1977)isconsideredtobelateUintanorMyton.H.E.Wood 11, identifier of the specimen, did not describe it or give the basis for his identi­fication. Wood (1941, 1949, 1954) published a chart showing the distribution and inferred stratigraphic relationships of American amynodont rhinocer­oses. In none of the papers does Wood give any taxonomic, morphologic, or stratigraphic evidencetoexplainhischoiceoftaxa,and onecanonlyassume that this information would have been given in his long projected, but never completed, study of Tertiary rhinoceroses. Wood (1941) specifically stated “no amynodonts known” in Wasatchian or Bridgerian. In addition, Wood (1941, 1949, 1954) recognized in the western interior only A. advenus in UintaA,A.advenus andA.reediinUintaB,andAintermedinsinUintaC. NeitherA. antiquus Scottand Osborn(1883)norA erectusTroxell(1921) are mentioned by Wood, but it is not evident from the literature when he had synonymized either of these species. In all of his charts, Wood recog­nized A. reedi from the Poway and A. sp. from the Sespe ofCalifornia. References to the occurrence of Amynodon in the Rocky Mountain area other than that of Peterson (1919) have been made. Granger (1910) reported on a fine skull of Amynodon? antiquus from Beaver Divide, Wy­oming. The same skull is mentioned in Scott (1945, p. 212) as having been identified by H.E. Wood as Amynodon advenus. Wood (1948) referred to the specimen, AMNH 14601 as A. advenus “definitely referable to this “ species, although a slightly progressive variant,” and further: Amynodon advenus is a Uintan index fossil, most characteristic of the early Uintan.” “ Emry (1975, p. 17) said, Amynodon advenus and Protoreodon parvusfrom the uppermost part of the Wagon Bed Formation near Wagon Bed Spring indicate more specifically ‘Uinta B’ temporal equivalence.” Riggs (1912, p. 22) in a section on the stratigraphy of the ‘Uintan Group’ of the Uinta Basin discussed the Amynodon Beds. “This includes substan­tially the same vertical series as Horizon B of Peterson and Osborn as far as the writer has been able to interpret them.” Riggs (1912, p. 23) did not describe, any specimens of Amynodon, but said, “However, specimens of Uintatherium (?), Stylinodon sp., Amynodon intermedins and Protylopus were recorded” at the Field Museum of Natural History in Chicago. The senior author measured a skull, FMNH 12184, and a lower jaw, FMNH 12191, (see table 3) that were collected by Riggs. They are herein referred toA. advenus. The occurrence ofamynodontidsinCaliforniawasfirstreportedbyStock (1933) when he described Amynodontopsis bodei based on a very fine skull that, according to Stock, is: “Larger than Amynodon antiquus, A. advenus and A. erectus, but less robust than A. intermedins. Skull dolichocephalic.”Stock (1933, p. 767) concluded that: “Possibly the type of A. intermedins shouldbereferredtoAmynodontopsis.” Theskullwascollectedfromlocality 150 of the California Institute of Technology (loc. LACM [CIT] 150). The collection from this locality was called Pearson Ranch local fauna by Golz (1976) and was correlated by him with the Lapoint of the Uinta Basin. In 1936 Stock referred more material including several fragmentary jaws, teeth, and a lower canine from loc. 150 to Amynodontopsis bodei. A lower jawfrom locality LACM (CIT) 147, also included in the Pearson Ranch 1.f., was referredbyStock(1936)toAmynodontopsisbodei. Stock(1939)described Amynodonreedibased on amaxillaryfragmentwithP4-M3collectedat LACM(CIT)loc.314. ThislocalitywasgivenbyStockasbeinginthePowayConglomerate but the revision of the stratigraphic section in the San Diego areabyKennedyandMoore(1971) wouldnowplacethelocalityintheFriars Fm. of the La Jolla Group. This nomenclature was used in Golz (1976) and Schiebout( 1977a). A. reedi is: “Smaller than Amynodon advenus, A. antiquusandA. erectusandresemblingA.sinensisinsize”(Stock, 1939).Inaddition Stock (1939) identified a single imperfect M 2 as Amynodon sp. possiblyadvenus and several parts of dentition referred to Amynodontopsis bodei from the “uppermost Eocene, California.” We assume this to be LACM (CIT) loc. 150, but Stock (1939) did not say so specifically. Schiebout (1977a) referred a left maxilla with an incomplete M 3 and a right uppercanine lacking the right half of the crown to A. reedi. Both specimens .are from the Friars Fm. Golz (1976) summarized the stratigraphic occurrence of amynodontsinsouthernCaliforniainhistable 1.ThepresenceofAmynodoncf. A. intermedins in southern California was indicated for the first time byGolz and Lillegraven (1977). This is recorded by them as having come from the Santiago Fm. and in their figure 6, “the most likely temporal positionof the land vertebrate faunas in the Santiaago Fm. is correlated with Uinta C ofUtah.Amynodontsin southernCalifornia,therefore,areknownfromstrati­graphicunits thathavebeencorrelatedwithWagonhound Member,theMytonMember, and the Lapoint of Utah. Apoorly-preservedlowerjaw,CM 734,wasfoundatSageCreek,Montana,andidentifiedbyDouglas(1903)asMetamynodonl.Matthew(Osborn, 1909, “ p. 99) listed this specimen as Metamynodon sp. (= Amynodon).” Wood . (1934, p. 252) said, “The Amynodont, CM 734, . seems to be in­ . ... .... side the limits of the genus Amynodon It is somewhat advanced over Amynodon antiquus, but is comparable in size with Amynodon intermedins from the Myton, and is more advanced in the loss of one incisor (I 3 ?), in the reduction in size of the remaining median incisor (Ij ?), in the slightlylarger canine and in the loss or extreme reduction of P2 . It is somewhat smaller and more primitive than, but otherwise rather close to, Stock’s form from the Sespe Formation of Ventura County, California.” Wood must have beenreferringtoAmynodontopsis bodeiStock.LateronWood(1934,p.255) statedinafootnotethat; “RestudyindicatesreferencetoAmynodonadvenus of the Lower Uinta.” The results of further collecting in the Sage Crpek area were presented by Hough (1955). She did not find any more amynodont material but referred CM 734 to Amynodontopsis cf. A. bodei. This was the first identification of that genus from the Rocky Mountain area. Hough (1955) applied the molar index proposed by Stock (1933) to the lower teeth, although she did not use the measurements given by Stock (1936) for a lower jaw that he referred to A. bodei. Bjork (1967)identifiedAmynodontopsis bodeifromtheSlimButtesarea of northwestern South Dakota. His material consists of associated right and left mandibles and isolated teeth. He disagreed with Hough’s identification of the Sage Creek specimen as Amynodontopsis and preferred Wood’s (1934) reference of CM 734 to Amynodon. Bjork (1967, table 4) gave comparative measurements for some late Eocene and early Oligocene amynodonts. Gazin (1956) in his review of the Badwater fauna did not describe or figure the Amynodon advenus specimen reported by Wood et al. (1936).Gazin (1956, p. 7), however, used Wood’s identification of A. advenus to support a temporal correlation between the Sage Creek and Badwater faunas. Gazin also assigned the Badwater fauna, as thenknown, to the Uintan. BlackandDawson(1966)listedthegenusAmynodon aspresentinWagon­hound, Washakie B, Poway, Myton, Hendry Ranch, Tapo Ranch, and Randlett. The Hendry Ranch amynodont is presumably the one mentioned first byWoodetal.(1935). WeareunabletoaccountforthegenusintheRandlett other than by their citation. Turnbull (1972) listed Amynodon sp. from Washakie B. of the Washakie Basin. Stock (1939) referred to an amynodont from Uinta A as follows: “Unfortunately, the fauna thus far known from Uinta A is a meager one. It contains, according to Dr. H.E. Wood, 11, an amynodont which he recog­nizes as of the species Amynodon advenus (No. 11983 Carnegie Mus.).” This may be the specimen or specimens that Wood (1941, 1949, 1954) used as a basis for the presence of A. advenus in Uinta A in his charts. Stock (1939)alsoreferred to asmallamynodontinthecollectionoftheAmericanMuseum “ . .. of Natural History (AMNH 1936A) that is the nearest resemblance in size to A. reedi . .” This specimen is from Uinta B of Utah and may be the .. basisofWood’s(1941, 1949,1954)chartshowingA.reedipresentinUintaB of the Rocky Mountain basins. AMYNODON ADVENUS (Marsh) 1877 Figs. 2-13, Tables 1-6,8, 11, 14, 15. — 3. Type. YPM 11763 LM 3 M Diceratherium advenum Marsh 1877, Uintan, Uinta Basin, Utah. , Synonyms.—Orthocynodon antiquus Scott and Osborn \SS3,Amynodon antiquus Scott and Osborn 1883, A. intermedins Osborn 1890, A. erectus Troxell 1921. Material. —Distorted skull (?female) alv 11-3,I1-3 alv C, P2 -M 3 41576-19; ,, somewhat crushed skull (?male) alv 11,I 1 12-3,I2-3 C, alvP2 ,P 3 -M3 41372-416; ,, , 2 skullfrag(?female)LC,P2-M3 -45;skullfragLP4-M3 -72;skullfragM ~ 4 -101; skull frag R root C, P2, -421; skull frag (?male), R C, -75; posterior halfskull,-410; occiput,-603; ,skullfrag(?female)alvC,alvP2 alvP3,P4 21 2 alvMl M LM LM -628. , , , Isolatedupperteeth, numerousincisorsofuncertainposition;C,4l372-51,-606; P2 41747-85; P3 -53; P4 41372-65, -444, -583-M 1 -430, 41576-29; ,, ,, M 2,41372-49, -74, -520, -570, -605;M3 -50, -413, -428, -613, -617. Uncrushedlowerjaw(?male)alvIx, 12,I2,alv 13,I3,C,P2-M3,41372-451; , dentary R alv P 2 , P3 -M 3 , 41747-75; dentary L P 3 -M 3 , 41747-76; dentaryLalvP2,P3-M3,41372-99;dentaryRM -46;dentaryLP3-Ml5-602; 2 dentaryLP^Mj,-612;dentaryLP4,41747-91;dentaryRM 3,42061-4. Isolated lower teeth, numerous incisors of uncertainposition; C, 41372­619; P2 , -171; -624; P3 , -66, -207, -600; P4 , -426, -598, 41747-50; M*, 41372-429;M2 -441, -442, -594, 41576-16, -24; M 3,41372-558. 4 Uncrushed ,juvenile skull without occiput, alv I 1 3 alv C, P l dP2 , ,, 41747-92. Juvenile lower jaw, alv alv C, dP2_4 , 41372-71; alv C,dP2-dP4,41747-90;dC,41372-492;dC,-544,dP2,-159; dP3 ,-64. Disarticulated postcranial material. Stratigraphic position. -Above the basal Tertiary conglomerate, if present and within the lower 50 ft. (15.2 m) of the Pruett Tuff, Buck Hill Group, BrewsterCo.,Texas,WhistlerSquatl.f.earlyUintan(fig. 1). 34 . Revised diagnosis.—Dentition 20r3 \ 3 milk dentition 3 \ 3 , Medium to moderately large amynodonts. Incisors erect; upper canines semi-procumbent and large (L 27 mm) in males, more vertical and smaller (L 17 mm) in females. Canine to second premolar diastema longer in males (45-48) than in the female (30). Premolar length approximately one-half the molar length. Facial fossae deeper in males. Skull longer in males. Crown height at metacone on unworn M 3 approximately 25-35 mm. Upperdentition.—Upperincisorsortheiralveoli arepreservedin41372-416 and41576-19. Intheformer,thebrokenbaseofrightI2andI3arepresent. Thecrownisbrokenoffof 11,I1 ispartlywornoffofbothI2andcompletely worn off of 13.I3 Incisors 1 and ,2 are oval in cross section where they emerge . from the alveolus; incisor 3 at the same position is more nearly circular in crosssection. ThewearonI2hasroundedofftheapexofthetooth,forming a dull chisel shape with the larger beveled surface facing posteriorly and Figure 2. Amynodon advenus. Lateral view of skull. Whistler Squat l.f. curving slightly to the exterior; a smaller beveled surface faces anteriorly. The only enamel left on the tooth is on the anteroexternal surface. The wear on I 3 has been more severe but the result is the formation ofa chisel-shaped tooth likethatof 12.I2 TheposteriorwearsurfaceonI 3isthelargerandwasformed . by the apex of the lower canine coming between it and the upper canine. The anterior wear surface on I 3 is smaller and is grooved. In the skull of the young adult, 41576-19 (figs. 2, 3), the alveoli fori1 are well-preserved. A small unerupted I 2 is present in a small alveolus on the right side. On the left side the alveoli for the three upper incisors are all approximately of equal size. Measurements for the upper teeth are given in table 1. The right upper canine is in place in the large skull 41372-416. It has an anterior wear surface for the lower canine and what appears to be an antero­extemal wear facet, but without the corresponding lower canines and incisors it is difficult to account for a wear surface in this position. An isolated an­terior part of a right premaxillary and maxillary, 41372-75 (fig. 4A), has the canine in place. In both 41372-75 and -416, the enamel has been worn from thefrontofthetooth. Thiswearsurfaceforthelowercanineisverticalwith respecttotheplaneofthepalate. Thewearsurfaceforthelowercanine(fig.5)gives the upper canine a triangular cross section with the base of the triangleanterodorsal and, in unworn or little worn upper canines, the apex of the triangle is posteroventral. The apex of the triangle is a ridge of enamel that ends at the base of the enamel. The root of the lower canine is oval in cross section so that when the wear proceeds beyond the enamel, a cross section of the tooth is even more ovate (fig. 5). This is confirmed in an iso­lated upper canine, 41372-606. As Colbert (1938, p. 323-324) pointed out,the shape of a cross section of the canine depends on where the cross section is made. Figure3.Amynodonadvenus,41576-19. Dorsalviewofskull.WhistlerSquatl.f. A young adult maxillary, 41372-45 (fig. 4B), with C-M3 has a much smaller canine than -75 or -416, measured at the base of the enamel (table 1). There is a posterior ridge, a small internal cingulum, and the enamel is still present aroundtheanteriorsurfaceofthecanineon41372-45,indicatingthat the specimen was younger than either -75 or -416. The former, however, is an adult, and would still be a much smaller individual than either of the latter. The C-P2 diastema in -45 is only 30 mm whereas in -75 and -416 it is 44 and 49 mm respectively. All three of these specimens are from the same quarry; and for this reason the specimens with the larger canines and longer C-P2 diastema are interpreted as males and the smaller specimens are interpreted as females. The left upper canine in 41576-19 (fig. 2) was lost during life and the alveolus covered with exostosis. No P 1 is present in any of the adult Texas amynodonts, but is found in milk dentitions. The ectoloph is well developed on P2 (fig. 6). The anterior extension is narrow but swells posterior to where the protoloph meets the ectoloph. There is an external rib at the position of the paracone. The an­terior and internal cingula are strong but the external cingulum is weak. There is considerable variation on the internal part ofP2 In 41576-19 (fig. 6), . the P 2 s are only slightly worn. The protoloph connects with the ectoloph just 3 mm above the base of the enamel so that it would form an isolated ridge separate from the ectoloph until the tooth reached a state of advanced wear. The metaloph, on the same tooth, is connected to the ectoloph and already shows wear. An isolated P2 ,41747-85, has the protoloph connected totheectolophabout9mmabovethebaseoftheenamel. Intheearlystagesof wear, as in 41576-19, P2 shows a pre-and postfossette. However, on a wornP2 onlytheprefossetteisstillpresent.Thepostfossetteisobliteratedby , heavier wear on the posterior part of the tooth. The P 3 is not as triangular as the P2 The rib at the position of the para­ . cone is more distinct. The external cingulum is very weak or absent, but the anterior, internal and posterior cingula are prominent. In 41747-53 the inter­nal cingulum is continuous internal to the protocone, however, on 41576-19 the internal cingulum is interrupted by the protocone on all upper premolars.In 41747-53 the metaloph is broad and short and meets the protoloph at its base. The metaloph in P3 of 41576-19 is very thin and long and connects high up on the protocone. There is a very small crista on 41747-53. TheprotolophonP2 isorienteddiagonallyacrossthetoothata45degreeangle to the ectoloph. In P3 the protoloph joins the ectoloph at right anglesbut curves posteriorly. The curvature varies somewhat but is approximatelythe same from P 3-M 3 If the metaloph on P4 joins the protoloph near the . base, the two lophs remain separate during much of the wear of the tooth. If they join higher up, however, they form a prefossette early in the wear stage. OffivemoderatelywornP4s,threehavetheprotolophandmetalophconnected, and two have them separated. However, 41372-72 and-444 are Figure 4. Amynodon advenus maxillaries with canines. A. 41372-75, reversed lateral view of right maxillary fragment with canine. Tooth is complete on internal side. Interpretedas a male. B. 41372-45, comparable portion of maxillary and canine. Interpreted as female.Whistler Squat l.f. more worn than 41372-65, and in the former the protoloph and metaloph are separate and in the latter, -65, they are joined. All adult premolars have a single internal cusp. The enamel on the outside of the ectoloph in a little-worn upper tooth curves internally to form a narrow ectoloph that faces internally and is almost vertical. As the enamel on the outer border of the ectoloph wears down, more and more dentine is exposed and the wear surface of the ectoloph is closer to horizontal. Only one specimen haslittle-wornfirstmolars(41576-19). Ontheseteeth, the ectoloph is well-defined, the parastyle is prominent, and a prominent an­terior rib and a less prominent posterior rib are present. The ectoloph ex­tends posterior to the metaloph and butts against the protoloph ofM Both 2. anterior and posterior cingula are prominent. A rounded swelling onthe pos­terior side of the protoloph forms an antecrochet. The wear surface on the ectoloph is almost vertical and the medial valley is prominent. In adult first molars most ofthese characters are worn away. The ribs become faint as the ectoloph is worn down; the external corners of the tooth are rounded off and the median valley eventually becomes a median ridge as the last of the enamel is worn off. The second upper molar is longer than M 1 or M The ectoloph is long 3. and straight with only the parastyle fold on its external surface. The para­style and the external surface of the ectoloph form a smooth line from the anterior comer of the tooth to the metastyle at the posterior corner of the tooth. The metastyle is not deflected labially. On worn M 2 s both the para­style and metastyle lose their prominence. The antecrochet ofM 2 is smaller thanthatofMl . In the third upper molar the metastyle is deflected externally, but the degree of deflection varies. In some teeth the angle between the metastyle and the metaloph is approximately a right angle; in 41576-19 it seems to be greater and in 41372-72 it is less. In the latter tooth, the metastyle is longand only slightly deflected; whereas in 41372-428 it is short, almost at a right angle to the ectoloph. The ectoloph on M 1 and M 2 is straight or slightly convex whereas on M 3 it is concave between the rib at the paracone and the metastyle. This is true only for slightly to moderately worn teeth, and a badly worn M 3 will have a convex external surface. The internal cingulum on the molars is usually interrupted by the proto­lophbutnotbythemetaloph. Ontheotherhand,theM2andM30f41576-19 have a small cingulum internal to the protoloph but none internal to the meta­loph. Thereis athinfilmofcementontheuppercheekteethof41576-19 and on some of the teeth from the Whistler Squat quarry although it is not as evident on the latter. We are unable to distinguish distinct and consistent differences in the upper dentition of amynodonts from the two localities that would imply more than one species. Therefore, we assume the variation is within the range of the age of the individuals or the sex of the individuals within a single population. Lower dentition. Only (fig. 7) furnishes evidence concern­ing the lower incisors. On the right side of this specimen there is part of an incisor and a single alveolus preserved. On the left side, there are three al­veoli. Those for and LI 2 are of about equal size (W=9.5 mm), but that forI 3isverysmallandcrowdedagainstthecanine. Theincisorontherightand the alveolus next to it are larger (W=12.5 mm) than those on the left. We do not attach any taxonomic significance to the absence of one incisor and assume it to be pathologic or individual variation. We consider-451 to be a male because of the large canines and long diastema. Measurements for the lower teeth are given in table 1. Isolated lower canines are easily distinguished by having the wear surface on the inside of the curve of the tooth. The crown of the tooth is triangularwith the apex of the triangle anterior and the base of the triangle posterior. In the canine of a young adult, 41372-619, the apex of the triangle is a ridgeofenamelextendingtothebaseofthecrown. Therootofthecanineisoval. The left canine in 41372-451 is in place and unbroken. The wear surface for the upper canine is present on the posterior side of the tooth (fig. 7) Figure 5. Top, Amynodon advenus, left lower canine, 41372-619, Whistler Squat 1.f.;Metamynodon mckinneyi n. sp., left lower canine, 41723-8, Serendipity 1.f.; bottom,Metamynodon chadronensis, right lower canine, FMNH PM 161, Porvenir l.f. and a deep wear surface for the I 3 is present on the internal side. The wear surface of the upper and lower canines is approximately perpendicular to a long horizontal axis through either the skull or lower jaw. The root of both upper and lower canines is almost straight and the sharp curvature of the tooth is at the base of the crown (fig. 5). This is very different from the long,smoothlycurved caninesofMetamynodon. The second lower premolar (fig.B) is a small tooth and is in place on 41372-451. In this specimen both right and left P2 appear to be single-rooted. Two isolated P2 s, -171, and -624, however, are both double-rooted. The latter is an unworn tooth and is used as the basis for this description.The protoconid is high and from it a cristid passes anterior and splits at the anterior end of the tooth into a more prominent anterointemal cingulumand a weak anteroexternal cingulum. Two cristids pass in a posterior direc­tion from the protoconid. The posteroexternal one passes down the external side of the tooth and curves internally to form a posterior and posterointer­nal cingulum. The posterointernal cristid is in the postion of a metaconid. There is a distinct but shallow groove on the external side of P2 that leads posteriorly from the protoconid to the base of the crown above the posterior root. The third lower premolar is like P2 except it is much larger and more molariform. The protoconid is distinct in unworn specimens. The anterior end of the metalophid curves into an anterointemal cingulum. The hypo­lophid is well developed and the external valley between the metalophidand hypolophid is distinct. Figure6.Amynodonadvenus,41576-19,uppercheekdentition.Top,lateralviewP2-M3 ; bottom,occlusalviewP2-M3 .WhistlerSquatl.f. Figure 7. Amynodon advenus, 41372-451.Lateral view of lower jaw.I1, alveolus I2,I2, and possibly I3, C, P2-M3. Whistler Squat l.f. Thefourth lowerpremolarisfullymolariform althoughnot aslargeas Ml The lower molars increase in size to M 3 and all have the typical metalophid-. hypolophid pattern. The groove on the external side of M mentioned 2 by Gromova (1954, table 1), is prominent on unworn or little-worn teeth and becomes less so on well-worn teeth. Milk dentition.—According to Osborn (1895) there are four upper and four lower deciduous premolars in A. intermedins. This is based on a referred specimen AMNH 1933 which was not figured by Osborn. Scott and Jepsen(1941) in their description of Metamynodon planifrons stated that; “The lower milk premolars are four in number, dP} and dP 2 having no successors in the second dentition.” Scott and Jepsen (1941) figured a juvenile skull and jaws (USNM 10602) that show four cheek teeth in the upper jaw but only three in the lower jaw. This is the same condition found in juvenileamynodonts in the Texas collection. Adescriptionofthesuccession ofmilkteethwasgivenbyPeterson(1920)forDiceratherium cooki {=Menocerasarikarense, videTanner, 1969). Tanner and Martin (1972) described the milk dentition of Hyracodon. We will follow the nomenclature of Peterson (1920) in which the first tooth in the upper cheek row is designated P 1 because it is not succeeded by another tooth. Therefore, we have labeled the four upper teeth in the juvenile skulls asPl dP2 dP3 dP4 . ThejuvenileskullsreferredtoareAmynodonadvenus, ,, , 41747-92 (figs. 9, 10, 11), Amynodontopsis bodei 41715-2 (fig. 16), and Metamynodon chadronensis FMNH PM 159. The nomenclature for the lower cheek teeth is less clear. On the second cheek tooth in both 41372-71 (fig. 12) and 41747-90 there are three cross­lophs. The anterior loph is small but distinct. This tooth also has the most wear. Peterson (1920) identified a similar tooth as dP 3 in Menoceras cooki. ———__———-—— ———­ 41372-430 32.4 38.6 7­ - ——————— ——-———­ 7453 18.8 24.0 1 4 __-—-_ ——­ ———__—_ —-———­ 41372-65 22.0 31.0 41372-629 37.2 8@ ——----_-—— 617 35.5 42.0 ————_—_ ——--—­ —— 41372-583 _ _ 22.0@ 31.41372­ __— —----­ ———__———--————­ 613 39.4 42.4 41372-444 21.4 31.0 41372­ __----_--­ l.f. 421 17.0 18.6 41372-50 39.2 43.3— — — —_ —-----— —-­ 41372­ Squat —_— --_—-­— -——­ — — ——— ———--— 747-85 15.4 18.1 41372-413 37.7 45.3 1 4 WhistlerTEETH —— ---_——— — —-— —­ — ————-— — 41372-75 28.2 21.9 41372-428 32.3 40.4 advenus,UPPER­ —-—__—-—— -­ __----— —­ 30 21.5 33.0 38.1 45.6 34.4 42.4 • 605 39.3 Amynodon41576 — 41372— 44.2 — ———---­ __-—-———­ of72 41372-115.6 18.9 36.5 34.5 41.3 39.0 47.1 41.9 46.2 41372-570 44.5 teeth— est. est. —— __ ——-­ lower41372-416 17056 115.0 22.0 21.5 19.0 25.0 20.8 33.1 26.9 37.4 38.4 45.0 39.0 74 48.1 and41372­ _ ---— _-—­ upper 41576-19R 232.0 173.561.0 116.0 12.8 16.9 22.0 29.1 24.5 37.8 41.8 44.7 45.8 51.0 39.5 45.5 41372-49 45.5 47.2 of _--­ — — —-­ 45 17.8 16.5 17.1 29 @ 41372-195 152 52.3 104.9 16.2 18.0 26.2 21.0 32.5 31.2 38.4 37.8 43.2 34.6 37.2 41756-40.5 38.5 Measurements— ­ 1. 33 3 3 3 -Mp2_p43LWLWLWLW WLWLW -M_p4 LWL wL WL wLWLWLW 23 1 2223 4 23M2 234 TableC-MM‘-MM‘L C-MM’-MPCPPPM M PpCPPPM M —— ——————— ——— — ——— 619 21.5 20.7 41372­ ————— — — — —— -————­ 41372-600 18.7 12.1 — ——­ — —-—­ _ — —-— 41372-612 19.3 13.0 22.1 15.3 _— —— ——— —-—-—— — —­ 41372-594 39.6 22.9 -—--——— ———-—--­ 41372-441 42.3 21.4 -———— — — —-—-——— ———-—-—-4 41372-442 38.7 19.6 42061-42.0 21.8 —— —--——-— —— —-—---—--— — 41372-426 24.4 14.7 41372-558 48.0 23.7 TEETH _ ~ --——— —— --—----— — —-—-­ 598 22.6 16.1 41576-24 37.5 20.5 41372-­ LOWER —— — — ——— --———— ——-—— -— —­ 41372-66 17.8 13.5 41576 16 39.1 21.2 — — ———-—--———-——— —-­ 747-76 43,5 20.2 747-50 23.8 16.0 1 41 4 @ est. -—— — — —-—I —— — 747-75 56 109.3 19.0 12.5 24.6 18.5 29.0 38.2 24,442.5 23.3 41372-207 18.9 12.9 1 4 est. ——— _ ——— @ 9.0 — __—-—— _ 41372-99 54 105.5 18.1 23.0 16.4 36.0@ 23.6 40.1 20.5 41372-624 13.5 —— — — _-—— ' i 41372-451 247.0 151.051.4 100.822.8 20.3 13.09.2 17.7 12.820.2 15.523.6 18.733.9 22.543,6 22.5 41372-171 i.i 9.1 cont. 1, 3 33 . 3 -m3p LwLwLWLwLWlWlw -m LwLWLwLWLWlwlw 23 223 p 23 22234 < p Pp mpCPPP Tablec-m'Vm,-mC PM. m c-m3 -p4M,-MM, m m Figure 8.Amynodonadvenus,41372-99.Top,occlusalviewP2-M;bottom,lateralview P2-M3 .InbothviewsP 2 isfrom41372-451.WhistlerSquatl.f. 3 If our identification is correct, there is no dPj in Amynodon advenus and thethreecheekteethinthejuvenilelowerjawsaredP2,dP3,dP4. Measure­ments for the juvenile upper and lower dentitions are given in table 2. Tanner and Martin (1972) described the milk dentition in Hyracodon.They showed conclusively that dPj is present in that genus and so labeled it, although it is not replaced. Peterson (1920) preferred to identify an un­replaced tooth as a member of the permanent dentition. Plate 1, figure d, inTanner andMartin(1972)showsboth dP2 anddP3 withthreecrosslophs,anddP3 isthelargesttoothintherow. Wefollowthetraditionalassumptionthat the teeth are lost from the anterior end of the premolar row and that in the North American amynodonts dP} and Pj are already lost by Uintan time. Unfortunately, the Texas collection doesnot include youngindividuals with permanent teeth replacing milk teeth. The lower jaws that do contain the milk dentition belong to very young animals; and, although the jaws were dissected, no trace of the permanent tooth caps could be found. A juvenile skull, 41747-92 has alveoli for three incisors and a canine. A P 1 is present on the right side (figs. 9, 10). It is a trenchant tooth with cristaeleadinginanteriorandposteriordirectionsfromtheprotocone. There is a single internal cross-ridge at the posterior third ofthe tooth and a stronginternal cingulum. There is no external cingulum. The molariform patternis well-developed on dP2 dP3 and dP4 The parastyle is strongly developed . , on all three teeth. The protoloph on dP2 curves more sharply in a posteriordirectionthantheprotolophsondP3anddP4. Agroupoffoldsintheenamel inthepositionofthecrochetarepresentondP4 .Thewearsurfacesareabout equalon dP2anddP3;whereasP1anddP4areunworn,althoughtheyare both fully erupted. Table 2. Measurements of upper and lower deciduous dentitions ofAmynodon advenus, Whistler Squat 1.f.; Amynodontopsis bodei, Skyline 1.f.; Metamynodon chadronensis, Porvenir l.f. UPPER TEETH Amynodon Amynodontopsis Metamynodonadvenus bodei chadronensis Slim Skyline Buttes, Whistler Squat l.f. l.f. S. Dak. Porvenir l.f. - 41747-4137241715-SDSM FMNH PM 92 492 2 10003 159 — P'-dP4 75.3 82.5 94.5 —-­ dCL 13.7 6.1 W 13.2 6.0 - P 1 L 12.7 11.2 9.7 15.1 — - W 8.7 8.5 12.8 dP2 L 16.8 18.6 18.7 19.3 @ — —­ W 16.5 20.8 20.5 dP3 L 24.0 21.5 29.4 —­ - — W 20.9 28.9 29.9 — dP4L 30.9 36.9 38.0 43.7 — W 26.9 33.7 37.0 40.0 —— ­ M1 L 38.2@ 54.2 —— ­ W 40.0 @ 50.2 —— ­ M 2 L 40.5 @ 67.4 - W 48.5 @ LOWER TEETH Amynodon advenus Whistler Squat l.f. 41372-41372-4 1747-41372-41372-41372­71 64 90 159 492 544 — —--­ dP2 -dP4 60.0 12.9 11.4 dCL ­W -13.3 14.5 — —-­ dP, L 14.4 14.2 14.9 W 8.4 7.6 8.0 -—— dP, L 21.5 22.2 23.7 W 12.3 11.5 12.5 —— — 25.3@ 27.1 dP4 L W ———14.2@ 15.7 Figure 9. Amynodon advenus, 41747-92. Ventral view of juvenile skull with alveoli for 1-3 dP 2-4 I and C, P l .Whistler Squatl.f. , Figure 10.Amynodonadvenus, 41747-92.Lateral view of juvenileskull withalveoli for I1-3 and C,P1, dP2-4.Vertical separationsare natural beaks and have been left that way. Whistler Squat l.f. There aretwolower jawsofveryyoungindividualsintheTexascollection,41372-71 (figs. 12A, B) and 41747-90. The former has the symphysis com­plete, but the three incisors and the canine are represented by alveoli. Three deciduous premolars are preserved on the right ramus and two on the left. On 41747-90 only the left ramus is preserved and it carries the same three deciduous premolars. The first cheek tooth, dP 2 , is a rather long, narrow, trenchant tooth (14.2 x 7.6 mm). The ridge leading forward from the proto­conid is straight and passes over a swelling in the position of a paraconid.There is no anterointernal cingulum on the RdP 2 of41372-71 and only faint anteroexternal and anterointernal cingula on the dP 3 The metastylid is . prominent, curving in a posterior direction and continuing to the base of the tooth. The hypolophid is well-developed. Thesecondlowercheekpremolar, dP3,isamuchlargertoothwiththree distinct crosslophs. A cristid leads forward from theprotoconid in a straight line to the anterior end of the tooth and splits into anteroexternal and an­terointemal cingula. There is a prominent paraconid, and a wear surface on it connects with the paracristid at right angles to form the anterior cross-crest. The metalophid is straight and slants posterointemally from the proto­conid at an angle of about 45 degress from the long axis of the tooth. The hypolophid has a broad curve to the entoconid. Of the three teeth in the jaw, this tooth is the most worn. The third deciduous lower cheek tooth, dP4 , is more like an adult molar. A paracristid curves anterointernally from the protoconid and turns posterior­ly to join an anterointernal cingulum. The metalophid is directed straightposterointemally as in dP2 Likewise the hypolophid is similar to that on . dP 3 but larger. In both juvenile lower jaws Mj has not erupted. Skull. —There are two adult skulls and one juvenile skull from the Whistler Squat local fauna. Although each comes from a different locality, they all occurred at about the same stratigraphic interval. The skull from the Whistler Figure 11.Amynodonadvenus,41747-92 .Dorsalviewofjuvenileskull.WhistlerSquatl.f. 26 Figure 12.Amynodonadvenus,41372-71.A.Lateral viewoflower jawwithdP2-4B.Occlusalandlateralview,dP. Squat quarry 41372-416, the largest, is rather badly distorted but seems to have been a long, narrow skull with large canines and a long post-canine dia­stema. Anotherskull,41576-19(figs.2,3),fromneartheWaxCamplocalityis almost free from distortion but the anterior part of the nasals is missing.Compared with 41372-416, 41576-19 was a shorter skull with smaller canines and a shorter diastema. The latter belonged to a younger individual because the M 3 shows very little wear. The snouts on both skulls are distorted so itisdifficulttobesureofthedepthofthefacialfossae. However,theyseem tolackthedepthofthoseofAmynodontopsis asillustratedbyStock(1933)andresemblemore closely YPM 11453,thetypeofAmynodonerectus, shown in Troxell (1921, table 3). The juvenile skull, 41747-92,(figs. 9, 10, 11), is uncrushed and the snout is well-preserved except for the anterior tip of the nasals. The dorsal part of the snout is sharply constricted just anterior to theorbits(fig. 11)andthisconstrictionpassesanteroventrallytothediastema betweenC andPl Inthejuvenileskullthetotalwidthfromoneanterodor­ . salcomerofthe orbitto theotheris 93mm. Theposterodorsallyconstricted snoutmeasuresonly33mmjustslightlyanteriortothatline(fig. 11).Innone of the three skulls do the facial fossae appear to extend posteriorly to the orbital rim as in the type of Amynodontopsis. The posterior edge of the facial fossae is about even with the anterior edge of the antorbital rim. The premaxillary bones are separate at the midline in both the adult and juvenile skulls. They do not form a median ridge as in Amynodontopsis, in which the premaxillaries are united in the midline. The premaxillaries ex­tend forward beyond the anterior tips of the nasals but no more so than on a horse and less than on a cow. Troxell (1921) stated that the premaxillaries are barely visible in a lateral view; however, the anterior end of the snout appears to be incomplete in YPM 11453, the specimen he was describing. “ Osborn (1890) described the premaxillaries ofA. intermedins as . . . rather narrow above and spread interiorly, rounding and arching forward into a broad incisive border.” This is the same condition found in 41576-19, but the premaxillaries are not united on the midline. The anterior tips of the nasals are preserved in 41372-416. They are longand slender anteriorly and project over the external nares not quite half as far as the incisive border. Posteriorly the nasals expand sharply in a lateral direction, and the lateral suture with the maxillary curves laterally and ven­trally to join the suture of the lachrymal. The nasals form a dorsolateral portion of the facial fossae. In the juvenile skull the two nasal bones are the shape of a capital T as seen from an anterodorsal view. This same skull has a clean break showing a cross section through the snout just anterior to the antorbital foramina. The section shows the squamous suture of the maxillarywith the down-turned lateral edges of the nasal. The maxillary forms most of the lateral surface of the facial fossa and shares the posterodorsal surface with the nasal and the lachrymal. The latter bone isveryrugoseandformstheanterodorsalrimoftheorbit.Ithas alow boss just over the lachrymal foramen. The medial extent of the lachrymal on the external surface of the skull is not as great as within the orbit. The frontals form the dorsal rim of the orbits, and the orbits are broadly openposteriorly. The nasal-frontal suture at the midline is over the approximate center of the orbit on the juvenile skull. The frontal-parietal suture on the midline is above the postglenoid process. This suture is very faint on the juvenile skull and not distinguishable on the adult. Nasals and frontals are aboutequallylong,approximately 100mm,whereastheparietalisonlyabout 35 mmlonginthejuvenileskull. ThiscontrastswithScottandOsborn’s(1883) “ description of “Orthocynodon” in which they said that the frontals ... are short and the parietals are elongated.” The malar terms the anteroventral border of the orbit and sweeps back to the zygomatic arch. On the juvenile skull there is a very small rugositythat forms the posteroventral comer of the orbit. In the adult skulls the malarprojects laterallyandventrallyjustabovethemiddleofM 2andbeneath the center of the orbit. The zygomatic arch is broad dorsoventrally in the adult skulls; on 41576-19 it is about 40 mm at its narrowest point and about 55 mm at the broadest. The sagittalcrest iscompleteintheadultskullsand is astraight,prominentridge. It is not preserved in the juvenile skull and was probably cartilaginous.Three nutrient foramina are present in each of the parietals in the juvenileskull whereas there are eight on the left side of41576-19. Thebasicranium is wellpreservedin41576-19(fig. 13)andin41372-410. The auditory meatus is open ventrally, as noted by Scott and Osborn (1833),Osborn (1895) and Troxell (1921). The basicranium and ear region super­ficially resemble that of the South American tapir. The postglenoid process on both specimens just previously mentioned is medial and its articular sur­face is oriented posterolaterally as in the tapir but the process in Amynodonis much thicker. The post-tympanic process of the squamosal is completein 41576-19 and is approximately the same height as the postglenoid process.The paroccipital process of the exoccipital extends beyond the post-tympanic process asinthetapir.Averyprominentforamen,probablythestylomastoid foramen, opens along the suture between the post-tympanic and paroccipital processes of the squamosal and exoccipital. We are uncertain of the positionof sutures for a mastoid bone on skull 41576-19, but the sutures show clearly ontheleft sideof41372-410andareessentially thesame asthoseshownbyScott and Osborn (1883). The ear region is nicely preserved in 41576-19 and is shown in figure 13. A very prominent processus hyoideus ofthe petrosal is present. Discussion. —Remains of Amynodon were the most commonly preservedfossils in the Whistler Squat quarry; however most of the material was disarticulated. A similar occurrence of amynodont material at approxi­mately the same stratigraphic level was found at a locality called Boneanza. This material combined with that from two other localities—all within the lower 50 feet (15.2 m) of the Pruett Fm. and all within a radius of about 4 mi (6.4 km) from Whistler Squat—very likely represents a sample from a single population. The specimens from localities other than the Whistler Squat quarry itself fell within the observed range of specimens from the quarry. The total number of complete teeth, skulls, jaws, and limb bones is small; however there are presently no published data for a comparablylarge sample of Amynodon. The most striking aspect of the sample was the high variability of adult individuals. A variety of characters has been used in the past to erect new taxa; one of these has been the number of premolars. It can now be shown that in North American amynodonts there are three permanent upper and lower premolars in adult individuals. The number of lower premolars is reduced to two in Amynodontopsis and Metamynodon. Other characters that have been used to distinguish taxa are the attitude of the canines, whether erect, oblique, or semi-procumbent; stronger or weaker cingula, deeper or shallow­er facial fossae; presence and number of cristae; and size. In addition, a Figure 13. Amynodon advenus, 41576-19. Ventral view of basi­cranium. CF condylar foramen; = = FLM foramen lacerum medius; == FO foramen ovalis; P petrosal;PH = processus hyoideus ofpetrosal; = PP paroccipital process ;PT = post­tympanic process of squamosal; SM = stylomastoid foramen. Whist­ler Squat l.f. so _»S *: •3 Uintan a 5 Os V r-00 co COqq00 00 NOqr-WhiteRiver, • £ 0 cor-CO0 1 1 ONdcod od NO CO CNdd VO >- (o00 NOCO CNCN CO CNcn CO CO Utah0 CN -a Q. OnIO 5 1 On nO 1 1 IO od 00* CO CN CN r-NO CN CN d od WashakieBasin, 100 •-a *-a .—i *-a cn CN co CO CO CO ~ Wyoming deposits CL >00 00 ro COr-r~co r-r-CO CO ONr-CO Uinta B, 5 r-CN O 00 aaH>¦£*o 1 145 1 ON 1 1 1 1 1 1 CNco CNcoco COco WhiteUtahRiver, amynodonts —* So 3 a3 t\L a 3-¦? Adobetown variousD -a CN r­ >>3 s 1 1101 1 111 1CNco COr-oc0 H 53 co co co CO CN co Washakie Basin of X Wyoming ® CN CNCO CN CL > 5> Uinta B, 111 111111l 1 00 CN CO CN COCO co Utah u dentitions NO 00 OnTt*CN ON ro O ON lower• *-a @) andL aa reedi 00 0 r-ON CO r^ qq Santiago Fm., >< 1 1 1co 1 1 1 1 11CNIOONONCOd 5 t) 2529 H •x 00 CN CN CN CN CO CN CO California upper of Measurements 3. S Cu LWL a Table aa O a a-a-Sis i 1i 111111111111111 Uinta B oq CS CSoqq VO oq 00 oo CS_ vqto ON CN VOqq 11T 1 „ ,1 *0 in'in CS*in-dcnro Os t"-’Ndin 00riq d Wagonhound, 00 inON cs CN rocscncs 5 Utah " Wagonhound, 1 CS 1 Iind Id vddCN I i O . —§ •'tin Ov i—i r—1 i cs 1cs cs ro cs i i Utah MM N — —2 —2222 — —2222212121 1941) ns Brule —— _ 24 5432 Metamynodon plantfroandJepsen,212-215 49-55 157-16337-39 31-34 21-28 15-20 29-33 21-27 42-43 53-58 57-60 32.5 (Scott _ N _2 _2321 _ —3332333333 and l.f. Fm. —— — -183.5 -141.8 -30.3 27.9 -33.9 30.8 _— Metamynodon chadronensis 180 40.4-45.0 13525 17.1-18.8 13.0-14.9 18.5-19.133 23.5-25.447.4-50.254.5-59.3 24.9-29.2 Porvenir 26.3-28.4 27.7-31.0 Chadron order. 147, N 1 2 311 3333443333 —3 and LOCFm. stratigraphic1933, channels l.f.)(CIT)x]nn -153 in34.5 4 Amynodontopsis bodei 1936,1939) 127.0 17.5 16.5 17.5-17.7 23.1-23.4 26.6-31.5 35.9-40.4 23.0-24.8 20.5-24.8 (SkylineButtes (Stock,139 38.0-39.8 102.5-115.1 12.3-13.4 16.4-17.1 16.7-22.1 40.5-44.3 CotterLACMSlim 3 M M - amynodontids— — _ — N 1 — 1 —12 — — _ —2222333322 1945) Basin Ave. Ave. —— 52 2416 30 of21-23 22-27 teethMegalomynodon regalis (Scott,290 185 134-141 21-22 14-17.5 19-20 39-49 44-54 51-53 26-27 Randlett Brennanppp°r2 r3 37.8 lower—— — 1 — —1 —1122 — —111 -222233 ofsp.N n. @@ —— — — —­ 280 2@ 140 14.2 33.0 measurementsMetamynodon mckinneyi185 46.34.4-36.4 32.8-33.5 20.7 25.8 36.3-38.0 23.6-24.7 46.1-47.8 27.3-29.3 47.5-54.0 25.9-28.5Uintan of 11 —13322337677218866 ranges l.f. N Squatest. 2 Observed38.2-41.5 21.5-22.8 20.3-20.7 11.1-13.5 17.7-19.3 12.1-13.5 14.7-18.523.6-29.0 33.9-42.3 40.1-48.0 20.2-23.7 134 Amynodon advenus Whistler272 247 1151 -143 51.4 100.8-109.3 9.0-9.20.2-24.6 18.7 19.6-24.4 Uintan 48.8 15. LWLWLWLWLWlWlw 44 11 -m3 -P-P 3 2223 2 p P1 P3 M,mTable I,-M, c-m3 P,-M, P1 M,-MC PM3 Upper dentition.—The adult skull (figs. 21, 22) has alveoli for three upper incisors per side (fig. 23), but the snout is broken on the juvenile skull. In the former the premolars and the first and second molars are so badly worn or broken off that nothing can be seen of their pattern. The third molar on the skull is badly worn but is better preserved in FMNH 161. These third molars are worn but still preserve the outer concave ectoloph and the rib at the paracone.Lower dentition.-A full dentition is preserved on the left ramus (figs. 24, 25) of FMNH PM 160. It is somewhat more worn than the type, AMNH 11866, but shows no morphologic differences. Upper milk dentition.—The juvenile skull FMNH PM 159 has Pl dP2 ,, dP3 dP4 M 1 and M 2 preserved (table 2). The first molar was erupted and M 2, was ,excavated by preparation. The occlusal pattern is worn off of P t and dP2-3 and the anterior comer is broken off dP4 . Their general shape is like that of the milk premolars of A. advenus but they are much larger. The M 1 of M. chadronensis is larger and higher crowned than that of the typeofA.intermedins. Thecrownheightmeasuredattheparaconeis44mm in M. chadronensis and about 37 mm in A. intermedins. The second molar, which has not erupted in FMNH PM 161, is an enormous tooth approxi­mately 67 mm as measured along the ectoloph. Discussion.—Metamynodon chadronensis is a rare form in the Porvenir local fauna of the Vieja area. A reduction in the back-levee swamp environ­ment in the Vieja may account for this. The climate seems to have gradually shiftedfrom amoremoistconditiontoadrier,perhapsmoreopensavannah condition from early late Eocene time to early Oligocene time. SUMMARY AND CONCLUSIONS A sample of amynodonts, referred to A. advenns, from a quarry at Whistler Squat, Brewster County, Texas, is sufficiently large for estimating the size of males and females in a single population. The males have large canines and longer C-P2 diastemas. The variation in tooth size is no greater than that given by Hooijer (1950) for the modem Hippopotamus. The variation of measurements of M 2 and M 3 and the astragali from the Whistler Squat quarry are comparable to that found by Hooijer (1972) for the Pliocene rhinoceros, Ceratotherium praecox, from a quarry at Langebaanweg, South Africa. Amynodon antiquus, A. intermedins and A. erectus are synonymized withA. advenus. A new species of Metamynodon, M. mckinneyi, has very large lower canines and only two lower premolars. It is referred with confidence to that genus. Metamynodon mckinneyi is associated with a Myton late Eocene fauna. Metamynodon bodei occurs still higher in the stratigraphic section in the SkylineandCotterchannels. BecauseoftheassociationofAmynodontopsisbodei and Hyaenodon cf. vetns, the fauna of the Skyline and Cotter channels is correlated with that of the Lapoint member ofthe Duchesne River Forma­ tion. Metamynodon chadronensis is identified in the Porvenir local fauna,early Oligocene, of the Vieja area. The samples of Metamynodon mckinneyi n. sp. and Amynodontopsis are small and nowhere have they been found together. For this reason we have referred them to the aforementioned genera knowing full well that further synonymization may be possible when large samples are available. There is no evidence on the type specimen of Amynodon antiquusfor the presence of nor on the type specimen ofAmynodon intermedins for P l . The formula for the adult cheek dentition in Amynodon, as presentlyknown, is Mjlj. The depth of facial fossae may be a function of sex and individual age and the preservation of the anterior ends of the nasals may be a function ofage. Amynodon advenus is the common Uintan form and is now well repre­sented by the collection from Whistler Squat. WhetherAmynodon advenus, Megalamynodon regalis, and Metamynodon chadronensis all represent a monophyletic series as Wood (1949) proposed will have to await largersamples. The more slender form, Amynodontopsis bodei, seems to have been widespread in North America and, so far at least, has not been found directly associated with the robust forms. LITERATURE CITED Bjork, P.R., 1967. Latest Eocene vertebrates from northwestern South Dakota. J. Paleon­tol. 41(l):227-236.Black, C.C., and M.R. Dawson, 1966. A review of late Eocene mammalian faunas from North America. Amer. J. Sci. 264:321-349. Colbert, E.H., 1938. 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Sci. 22(5):260-265. , 1939. Eocene amynodonts from southern California. Proc. Nat. Acad. Sci. 25(6):270-275. Szalay, F.S., and J.A. Wilson, 1976. Basicranial morphology of the early Tertiary tarsii­form Rooneyia from Texas. Folia Primatol. 25:281-293. Tanner, L.G., 1969. A new rhinoceros from the Nebraska Miocene. Bull. Univ. Nebraska State Mus. 8(6):395-412. ,and L. D. Martin, 1972. Notes on the deciduous and permanent dentition of the hyra­codonts. Trans. Nebraska Acad. Sci. 1:12. Troxell, E.L., 1921. New amynodonts in the Marsh Collection. Amer. J. Sci. (ser. 5) 2: 21-34. Turnbull, W.D., 1972. The Washakie Formation of Bridgerian-Uintan Ages and the related faunas, p. 20-31, In Guidebook field conference on Tertiary biostratigraphy of south­ern and western Wyoming; Aug 5-10, R.M. West, Coordinator. Wilson, J.A., 1966. A new primate from the earliest Oligocene, West Texas, preliminary report. Folia Primatol. 4:227-248. ,1971a.Early Tertiary vertebrate faunas, Vieja Group, Trans-Pecos Texas: Agrio­choeridae and Merycoidodontidae.Texas Memorial Mus. Bull. 18. 83 p. , 1971b. Early Tertiary vertebrate faunas, Vieja Group, Trans-Pecos Texas. Entelo­dontidae.TexasMemorialMus.Pearce-SellardsSer. 17. 17p. , 1972. Vertebrate biostratigraphy of Trans-Pecos Texas and northern Mexico, p. 157-166. In Geologic framework of the Chihuahua tectonic belt. West Texas Geol. Soc, R.K. DeFord Symposium. , 1974. Early Tertiary vertebrate faunas Vieja Group and Buck Hill Group, Trans-Pecos Texas. Protoceratidae, Camelidae, Hypertragulidae. Texas Memorial Mus. Bull. 23. 34 p. ,1977a.Early Tertiary vertebrate faunas Big Bend area Trans-Pecos Texas. Bronto­theriidae. Texas Memorial Mus. Pearce-Sellards Ser. 25. 15 p. , 1977b. Stratigraphic occurrence and correlation of early Tertiary vertebrate faunas,Trans-Pecos Texas. Part 1: Vieja area. Texas Memorial Mus. Bull. 25. 42 p. ,and F.S. Szalay, 1976. New adapid primate of European affinities from Texas. Folia Primatol. 25(4):294-312. , J.B. Stevens, and M.S. Stevens, 1979. New cross-section from southern Davis Mountains to northeast Solitario, p. 14 7-149. In Conference proceedings and guide­book, Cenozoic geology of the Trans-Pecos volcanic field of Texas. Bur. Econ. Geol.,Univ. Texas—Austin, Guidebook 19. ,P. C. Twiss, R.K. DeFord, and S.E. Clabaugh, 1968. Stratigraphic succession, potas­sium-argon dates and vertebrate faunas, Vieja Group, Rim Rock Country, Trans-Pecos Texas. Amer. J. Sci. 266:590-604. Wood, A.E., 1973. Eocene rodents, Pruett Formation, southwest Texas; their pertinence to the originof theSouthAmerican Caviomorpha.Texas Memorial Mus. Pearce-Sellards Ser. 20. 41 p. , 1974. Early Tertiary vertebrate faunas, Vieja Group, Trans-Pecos Texas; Rodentia. Texas Memorial Mus. Bull. 21. 112 p. Wood, H.E. 11, 1934. Revision of the Hyrachyidae. Amer. Mus. Natur. Hist. Bull. 67:181-295. 1937. 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Amer. 1935,p. 394-395. , THE PEARCE-SELLARDS SERIES ThePearce-SellardsSeries areoccasionalpaperspublished by TexasMemorialMuseum, The University of Texas at Austin, 2400 Trinity, Austin, Texas 78705. Other serial publi­cations include the Bulletin, Museum Notes, and Miscellaneous Papers. A complete list may be requested from the above address. 1. Fossil Bears from Texas, by Bjorn Kurten, 1963; 15 pages, 6 figures 2. Post-Pleistocene Raccoons from Central Texas and Their Zoogeo­graphic Significance, by T.N. Wright and E.L. Lundelius, Jr., 1963;21 pages, 7 figures $0.75 3. A New Fossil Tortoise from the Texas Miocene, by W. Auffenberg,1964; 10pages, 2 figures $0.75 4. The Osteology and Relationships of the Pliocene Ground Squirrel,Citellus dotti Hibbard, from the OgallalaFormation ofBeaver Coun­ty. Oklahoma, by M.S. Stevens, 1966; 24 pages, 6 figures $l.OO 5. The Status of Bootherium brazosis, by C.E. Ray, 1966; 7 pages,2 figures $0.75 6. Geologic Reconnaissance of the Fort Davis National Historic Site, Texas, by A.G. Everett, 1967; 19 pages, 12 figures $0.75 7. MammalianRemains fromRattlesnake Cave,KinneyCounty,Texas, by H.A. Semken, 1967; 10 pages, 1 figure $0.75 8. DevelopmentofTerminalBudsinPinyonPineandDouglasFirTrees, by C.E. Douglas and J.A. Erdman, 1967; 19 pages, 5 figures $0.75 9. Toxotherium(Mammalia: Rhinocerotoidea)fromWesternJeffDavis County, Texas, by J.M. Harris, 1967; 7 pages, 1 figure $0.75 50.75 10.NewBrazilianFormsofHyla,byB.Lutz, 1968;18pages,8figures 50.75 11. Taxonomy of the Neotropical Hylidae, by B. Lutz, 1968; 25 pages,4 figures $ 1.00 12. Geographic Variation in Brazilian Species of Hyla, by B. Lutz, 1968; 13 pages, 6 figures $0.75 13. Remarks on the Geographical Distribution and Phyletic Trends of South American Toads, by J.M. Cei, 1968; 20 pages, 6 figures $0.75 14. A New Genus of Eomyid Rodent from the Oligocene Ash Spring Local Fauna of Trans-Pecos Texas, by J.M. Harris and A.E. Wood, 1969; 7 pages, 1 figure $0.75 15. New Early Miocene Formation and Vertebrate Local Fauna, BigBend National Park, Brewster County, Texas, by M.S. Stevens, J.S. Stevens, and M.R. Dawson, 1969; 52 pages, 15 figures $1.50 16. New Fossil Rodents from the Early Oligocene Rancho Gaitan Local Fauna, Northeastern Chihuahua, Mexico, by A. Wood and I. Ferrusquia-Villafranca, 1969; 13 pages, 3 figures $0.75 17. Early Tertiary Vertebrate Faunas, Vieja Group. Trans-Pecos Texas: Entelodontidae, by J.A. Wilson, 1971; 17 pages, 6 figures $0.75 18. Early Tertiary Vertebrate Faunas, Vieja Group, Trans-Pecos Texas: Equidae, by A.-M. Forsten and P.O. McGrew, 1971; 16 pages,2 figures $0.75 19.The GenusDinofelis(Carnivora,Mammalia)intheBlancanofNorth America, by Bjorn Kurten, 1973; 7 pages, 1 figure $0.75 20. Eocene Rodents, Pruett Formation, Southwest Texas; Their Per­tinence to the Origin of the South American Caviomorphs, by A.E. Wood, 1973; 40 pages, 8 figures $1.25 21. Miocene Vertebrates from Aguascalientes, Mexico,by W.W. Dalquest and O. Mooser, 1974; 10 pages, 5 figures $0.75 22. The Fossil Horses of the Texas Gulf Coastal Plain: A Revision, by A. Forsten, 1975; 86 pages, 7 figures $2.50 23. Early Tertiary Vertebrate Faunas, Vieja Group, Trans-Pecos Texas: Insectivora, by M.J. Novacek, 1976; 18 pages, 6 figures $l.OO 24. A New Species of Bufo (Anura: Bufonidae) from Africa’s Dry Sa­vannas. by M. Tandy, J. Tandy, R. Keith, and A. Duff-McKay, 1976; 20 pages, 4 figures $l.OO 25. Early Tertiary Vertebrate Faunas Big Bend Area Trans-Pecos Texas: Brontotheriidae, by J.A. Wilson, 1977; 17 pages, 5 figures $l.OO 26. Ethnic Identities of Extinct Coahuiltecan Populations: Case of the Juanca Indians, by T.N. Campbell, 1977; 16 pages $l.OO 27. A New Systematic Arrangement forPhilodryas serra (Schlegel) and Philodryas pseudoserra Amaral (Serpentes; Colubridae), by R.A. Thomas and J.R. Dixon, 1977; 20 pages, 8 figures $l.OO 28. Further Study of Castolon Local Fauna (Early Miocene) Big Bend National Park, Texas, by M.S. Stevens, 1977; 69 pages, 18 figures . .$2.00 29. Butterflies from the Middle Eocene: The Earliest Occurrence of Fossil Papilionoidea (Lepidoptera), by C.J. Durden and H. Rose,1978; 25 pages, 7 figures $l.OO 30. A Dasyleptid from the Permian of Kansas, Lepidodasypus sharovi n. gen., n. sp. (Insecta: Thysanura: Monura), by C. J. Durden, 1978; 9 pages, 3 figures $0.75 31. Early Tertiary Vertebrate Faunas, Big Bend Area Trans-Pecos Texas; Simidectes (Mammalia, Insectivora), by E.P. Gustafson, 1979; 10 pages, 3 figures $0.75 32. Late Hemphillian Mammals of the Ocote Local Fauna, Guanajuato,Mexico, by W.W. Dalquest and O. Mooser, 1980; 25 pages, 5 figures 51.50 33. Early Tertiary Vertebrate Faunas, Trans-Pecos Texas; Amynodonti­dae, by J.A. Wilson and J.A. Schiebout, 1981; 62 pages, 25 figures 52.00