THE PEARCE- SELLARDS Series
NUMBER 17
Early Tertiary Vertebrate Faunas, Vieja Group, Trans-Pecos Texas: Entelodontidae
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JOHN ANDREW WILSON
July, 1971
TEXAS MEMORIAL MUSEUM / 24TH & TRINITY / AUSTIN, TEXAS W. W. NEWCOMB, JR., DIRECTOR
Introduction Earlier publications, primarily Stovall (1948), DeFord (1958), Wilson et al. (1968) and Wilson (1971), discuss the location, previous work, stratigraphy, and age of the Vieja Group. A full repetition is not necessary in this paper, but to facilitate reading, the stratigraphic section and the positions of the local faunas are given in fig. 1.
ABBREVIATIONS AXSP Academy of Natural Sciences, Philadelphia CM Carnegie Museum, Pittsburgh FMXH Field Museum of Xatural History, Chicago TMM Texas Memorial Museum, Austin l.f. local fauna Collection numbers without prefix belong to TMM’" and those numbers preceded by a hvphen include the five-digit locality number preceding. All measurements are in millimeters. General areas for local faunas are indicated diagrammaticallv in Wilson et aJ. (1968, figs. 1 and 2). Detailed descriptions of localities are on file at the Vertebrate Paleontologv Laboratory, Balcones Research Center, The Uni- versity of Texas at Austin.
ACKNOWLEDGMENTS XSF grants G 13270 and CP 1050, the Geologv Foundation and The Uni- versity of Texas at Austin have supported the field work, the laboratory pre- paration, and, in part, the cost of illustrations. Mr. and Mrs. Howard Gibson of Terlingua, Texas, generously donated the very fine skull and jaws of Archaeotherium to the collection of the Texas Memorial Museum. The Carnegie Museum specimens were loaned to me for studv by Drs. Craig C. Black and Mary R. Dawson. Dr. Rainer Zangerl, of the Field Museum of Xatural History, Chicago, has generouslv extended the loan of Porvenir local fauna material collected and originallv loaned by Prof. Bryan Patterson, now of Harvard University. I am grateful for their coopera- tion. Dr. Mary R. Dawson kindly read the manuscript, but I am responsible for the conclusions. The drawings were made by Margaret S. Stevens.
° This collection and the Vertebrate Paleontology Laboratory were formerly under the administrative control of the Bureau of Economic Geology. They were transferred to the Texas Memorial Museum, The University of Texas at Austin, in November, 1969.
3 Fig. 1. Succession of rock-stratigraphic units and position of local faunas in the Vieja Group, Trans- Pecos Texas. (After Wilson el al. 1 968).
SYSTEMATIC PALEONTOLOGY Order Artiodactyla Owen, 1848 Suborder Suiformes Jaeckel, 1911 Infraorder Palaeodonta Matthew, 1929 Superfamily Entelodontoidea Colbert, 1938 Family Entelodontidae Lydecker, 1883 Subfamily Entelodontidae Osborn, 1909 Genus Brachylujops Colbert, 1938
4 3 Fig. 2. Brachyhyops wyomingens.'s. A. CM 1 1 989. Occlusal view of roots of P 5, P*; M lM ; Duchesne, La Pointe, Utah. B. CM 12079. Occlusal view M l -M 3. Red Narrows, N. of La Pointe, Uintah Co., Utah. Both figs. X .67.
Brachyhyops tvyomingensis Colbert, 1938 Figs. 2, 3; tables 1, 2.
4 3 Type.—CM 12048, skull with badlv worn P -M . Beaver Divide, Wvo. Referred Material. -FMNH PM 150, fragmentary lower jaw with poorly l-3 preseryed P 3 -M 3 (Porvenir 1.f.); CM 12079, fragmentary left M , and CM
~3 11989, fragmentary right M , both from Utah.
5 Fig. 3. Brachyhyops wyomingensis. FMNH PM 150. Lateral view of lower jaw and occlusal view of P -M . X .67. 4 3 TABLE 1 Measurements of upper teeth of Brachvhyops wyomingensis, type (after Colbert, 1938), CM 12048, CM 12079, CM 11989 or 18668 and of Archaeotherium cf. mortoni, TMM 40840-49 and FMNH PM 98. Brachijhyopsivt/omingensis B.bncnwiiominaensisxvvominEensisp’ £ ,—.£ ,—.£ • •' IOCO®05ioCO bbbbIdTypei—.gjFMNIICDOGOPIpM H-4-Archaeotherium|—i00pcjy[CDWpPM1Arr.hnpnfhpriiim|—iPp pio
. longer than P 4 , no diastema between P 4 and P 3 Description. —The lower jaw, FMNH PM 150 fits very closely with the upper dentition of the tvpe of Brachyhyops wyomingensis. The upper teeth of the Carnegie Museum specimens are of the correct size to be referred to the same species. The roots of P3 and P 4 are yisible in CM 11989 (fig. 2); P 4 is three rooted. P is crowded against P 4 . The M and M 1 are broken in both Carnegie Museum specimens. The better M is preserved on CM 12079. There is an anterior cingulum but no internal cingulum. The wear facets of the proto- cone, protoconules, hvpocone, and metaconule are present. Specimen CM
7 TABLE 2 Measurements of lower teeth of Brachyhyops wyomingensis FMNH PM 150, Eoentelodon yunnanensis. Geol. Mus. CPF Vm 0051 and Archaeotherium cf. mortoni, TMM 40840-49, -33.
Brachyhijops EoenteJodon Archeotherium 40840-33 wyomingensis yunnanensis 40840-49 FMNH PM 150 Geol. Mus. CPP Vm 0051 C L 17.4 W 12.0 P, L 12.3 W 6.8
P 2 L W 25.1 P :! L W 11.5
P4 L 18.4 14.6 26.4 W 10.4 7.5 11.8 Mj L 15.6 13.2 21.4 W 11.7 9.6 M, L 16.3 16.0 23.5 W 14.3 11.3 15.3 23.2 M 3 L 17.5 14.2 21.9 W 13.0 10.2 15.5 11.4
11989 has the better preserved M 2, The external cusps are broken but enough is present to show they were higher than the internal cusps. This was prob- ably also true for Ml . The protoconule and metaconule are prominent and lines through them from the paracone to the protocone and metacone to the in hvpocone respectively curve posteriorlv. On M 3, which is well preserved both specimens, there is a cingulum surrounding the whole tooth. The para- cone is the largest cusp; protocone, protoconule, metacone and metaconule are present. The hypocone is absent. The tooth has a rounded triangular out- line. The two Carnegie Museum specimens from Utah are so close in size and tooth wear that they could possiblv be from the same individual. On the icferred lower jaw from Texas, FMNH PM 150 (fig. 3), only the left Mj is complete. The central part of the symphysis is present so that the length of the jaw is determinable but the dorsal part, including the alveoli for the incisors, canines, and anterior premolars, is missing. The ventral borders of the rami are also missing so that it is impossible to tell whether bosses were present. Enough of the right P 3 is preserved to determine that it was as large
8 as and probably larger than P4 . It is crowded against P 4 which in turn is closely set against M,. The right P 4 shows a small anterior cingulum but no sign of a paraconid. The main cusp on the left P 4 is high and between its base and the posterior cingulum is a small median accessory cusp. The arrange- ment of the cusps on Mi is exactly like that on M 4 of Archaeotherium from the Brule of South Dakota. The anterior cingulum is faint, the paraconid and metaconid form anterointernal cusps that join to a single cusp with slight wear. The anterior cusps are higher than the posterior cusps. A very small tu- bercle is present between the posterior cusps in the position of a hypoconu- lid. The largest molar is M>. It is poorly preserved on the left side only but ap- parently had the same pattern as Mi. The right M 3 has lost the enamel from the heel. Para-and metaconids are present in line anterioposteriorly. The ento- and hvpoconids were present and from the preserved dentine it is possible to tell that there was a median cusp on the heel and that the heel was very short. The ventral edge of the lower jaw is missing in FMNH PM 150 so that it cannot be told whether ventral bosses were present or absent. Futhermore, the depth of the jaw beneath the cheek teeth is not known. The depth of jaw beneath the molars might have been the same as in TMM 40840-49, a lower jaw of Archaeotherium from the Little Egypt l.f. Also because much of the elongation of the lower jaw in Archaeotherium occurs in the anterior premolar area and this area is broken off in FMNH PM 150, it might be claimed that this is a small Archaeotherium. The presence of FMNH PM 98 in the Porvenir 1.f., although slightly higher in the section, indicates to me that both Archae- otherium and Brachyhyops were probably present at the same time and that one is not ancestral to the other. The cheek teeth of FMNH PM 150 are so much smaller than those of any Archaeotherium of the Little Egypt l.f. and the near perfect fit of FMNH PM 150 with the type skull of Brachyhyops leads me to this identification.
. since time Relationships.r .—Colbert (1938) described the type skull and that nothing has been added to the knowledge of Brachijhyops. Colbert (1938) tentatively assigned Brachyhyops to the Choeropotamidae. Scott (1945), Simpson (1945), and Romer (1966) followed Colbert in this family assign- ment. Colbert (1938) carefully compared the type, showing likenesses and differences, with members of the families Dichobunidae, Choeropotamidae, Cebochoeridae, Entelodontidae and Tayassuidae. In the same paper he referred Parahyus along with Brachyhyops to the Choeropotamidae and in this too he was followed by Scott (1945) and Simpson (1945). Gazin (1955), however, placed Parahyus in ancestral position to Achaenodon within the subfamily Helohvinae of the family Dichobunidae but he did not mention Brachyhyops. Romer (1966) separated Parahyus and Achaenodon from ?Brachyhyops bv placing them in the family Achaenodontidae of the sub- order Palaeodonta. He kept ?Brachyhyops in the Choeropotamidae but placed that familv in the superfamily Entelodontoidea of the suborder Suina.
9 Although I have not made comparisons with the type skull, I have com- pared the Carnegie Museum maxillaries and Field Museum of Natural His- torv lower jaw with European representatives of the Choeropotamidae and find that while the skull resemblances mentioned by Colbert (1938) are present, the tooth and skull resemblances to North American entelodonts are so great that thev outweigh evidence for possible relationship with the Choeropotamidae. It seems to me that Braclujhijops is a short-faced entelo- dontoid and obviouslv one that did not survive verv long. Until more material is found, particularly an associated skull and jaw, this assignment will remain tentative. Chow (1958) described a lower jaw and named it Eoentelodon yunnan- ensis. It came from the Upper Eocene, lower part of the Liman Formation, Yunan, Peoples Republic of China. The table of measurements shows that the Asiatic species is much smaller than the Texas specimen referred to Bracluj- htjops. The symphysis of the jaw of Eoentelodon is not present so it is im- possible to say whether elongation had already begun in the Late Eocene. P Eoentelodon does have an incipient mental tubercle beneath 4 and M v Chow (1958) assigns Eoentelodon to the Entelodontidae and makes it ancestral to both the European Entelodon and the North American Archaeo- therium. Eoentelodon is the earliest known member of the family Entelo- dontidae. The stratigraphic position of Brachylu/ops and the earliest Archaeotherium in North America is now of importance. Colbert (1938), in his description of the tvpe, states, “Horizon: From the uppermost level of the Uinta Formation, immediately beneath the basal Oligocene agglomerate at Beaver Divide.’ Colbert (1938) considered the beds from which the type was collected to be Uintan and therefore Late Eocene. Scott (1945) considered the Duchesne River Formation of Utah to be Oligocene and correlated the upper part of the “Uinta” at Beaver Divide with it. He discusses the reasons in some detail. In this age assignment of the Duchesne River Formation he was following the staff of the Carnegie Museum, Peterson, Kay and Burke, all of whom wrote on the Duchesne River Oligocene. Simpson (1946) considered the Duchesne River Eocene and H. E. Wood (1948) considered that part of the Beaver Divide section from which Brachijhijops was collected to be Uintan. Gazin (1955, p. 7) speaks of the section at the Beaver Divide:
Much confusion exists as to the relative ages of horizons represented in the se- quence exposed along the Beaver Divide at the southern rim of the Wind River Basin. Uintan beds here have produced Camelodon arapahovius and probably several specimens of uncertain locality which have been attributed to the Beaver Divide conglomerate. The top of the Uintan sequence is deeply channeled, and the fill has produced remains of Oligocene age. At least one of these, the Braclujhijops wyomingensis skull, was described as coming from the uppermost part of the
10 Uintan sequence. I am informed by Dr. Franklvn B. Van Honten [personal com- munication] that the Beaver Divide conglomerate overlies the channel fill and so is likewise Oligocene in age. The materials of Eocene aspect attributed to the Beaver Divide conglomerate are for the most part uncertain as to locality, particularly the immature specimen described bv Scott as Mesagriochoerus primus, collected by a local resident. . . . An immature jaw fragment collected by Van Honten from beds undoubtedly a part of the Beaver Divide conglomerate resembles Protoreodon, but the two lower teeth preserved are not truly diagnostic so that a small species of of Agriochoerus may well be represented. It would seem, from a review of the Beaver Divide materials and occurrences, and from field information furnished me bv Van Honten and others, that the Duchesnean interval is not represented by sediments in the Beaver Divide. The hiatus in time is further indicated bv the marked disconformitv.
Information from the Vieja Group of West Texas is helpful. The lower jaw, FMXH PM 150, was collected from an interval called by Prof. Brvan Patter- son the "Big Red horizon (field notes and specimens, FMXH). In the stratigraphic section worked out bv DeFord (1958) and his students, this is within the lower 100 ft. of the Chambers Tuff Fm. which lies on the Buck- shot Ignimbrite. This part of the Chambers Tuff contains the Porvenir local fauna. The Field Museum collection also contains a fragmentary M l-3 which I will refer to Aichaeotherium. This specimen was collected from Patterson’s ‘‘Blue Cliffs horizon. From the field notes and sections kindly loaned to me bv Prof. Patterson, this horizon is approximately 200 ft. above the Buckshot Ignimbrite and overlies his "Big Red horizon. It would still be in the lower part of the Chambers Tuff and a part of the Porvenir local fauna. Unmistak- able small Archaeotherium occurs in the upper part of the Chambers Tuff in the Little Egvpt local fauna. The specimen CM 12079 from the "Lapointe Horizon, Red Xarrows N. of La Pointe collected bv J. Lerov Kav, 1936, in my opinion, can be referred to Brachi/ht/ops m/omingensis. The locality information of CM 11989 is not so definite but the two specimens are so similar, even in the degree of wear, that they could represent right and left dentitions from the same jaw. If mv re- ferrals are correct, the Lapoint Member of the Duchesne River Fm. of Utah, the Porvenir local fauna from the Chambers Tuff Fm. of Texas, and a channel fill on Beaver Divide, Wyoming contain Brachylujops. The Porvenir l.f. contains both Protoreodon and Agriochoerus (Wilson, 1971) which are men- tioned bv Gazin (1955, p. 7) as having been found at Beaver Divide. Charac- teristic Oligocene genera, 'Slesohippus, Hi/aenodon and Leptomenjx, are also present in the Porvenir local fauna. Brachijhijops furnishes a tentative corre- lation and indicates an Oligocene age for the upper part of the Duchesnean of Wood et ah (1941). It further supports the suggestion of Wilson et ah (1968, p. 603) that the Duchesnean Age straddles an Eocene-Oligocene
11 boundary and that a satisfactory solution might be to use only Uintan and Chadronian. Gazin (1956) gives a name, Dyscritochoerus lapointensis, to a fragment of a lower jaw, CM 11912, described by Peterson (1934) as (?) Helohyus sp. The measurements for CM 11912 are slightly larger than those of FMNH PM 150. The discovery of more and better material will be necessary before the relationships of Dyscritochoerus lapoint:nsis and Brachyhyops wyomingensis can be ascertained.
Genus Archaeotherium Leidy, 1850 Archaeotherium cf. mortoni Leidy, 1850 Figs. 4-6; tables 1, 2. Type.—ANSP 10606,fragment of skull with P3 and P'. Referred Material.—TMM 40840-15, articulated skull and lower jaws, frag- ments of vetebrae; 40840—49, anterior part of skull with I '-M and lower jaw
3 40840-33, lower jaw with L, C-M , but teeth in both are poorly preserved; l fragment with M 3; FMNH PM 98, poorly preserved M -M" and base of P , from the Little Egypt 1.f.; 40283-95, a PM 1 from the Ash Spring l.f. Stratigraphic Position. FMNH PM 98 approximately 200 ft. above base of Chambers Toff Formation, Porvenir local fauna; TMM 40840-15, -33, -49 upper part of Chambers Tuff Formation, in the pale red sandstone at approx- imate position of the Bracks Rhyolite Formation. Description. —The Archaeotherium maxillary fragment from the Porvemr l.f. is so poorly preserved that it does not warrant detailed description. The teeth of this specimen, FMNH PM 98, are enough larger than those of CM 11989 and CM 12079 so that the former is referred to Archaeotherium rather than Brachyhyops. The Texas Memorial Museum specimens are better preserved, especially 40840-15. This skull and lower jaw is of an adult individual; M 3 is well worn and the pattern is completely worn off the internal part of M J (fig. 6). The posterior part of the skull on the left side is broken off justbehind the glenoid fossa and on the right side just behind the external auditory meatus (fig. 5). J ft Figures 4 and 5 show the elongation of the snout and lower jaw which occurs anterior to VI. The lower canines and incisors are almost recumbent. No medial ventral bosses are found on the lower jaw of 40840-15 and only very small ones on 40840-49. Anteriorly, a narrow curved crest (not round and knob-shaped) follows the curvature of the symphysis and projects laterally (not ventrallv), (fig. 4). There is a short suborbital process. It projects smoothly in a postero-ventral direction following the line of the zygomatic arch with only a verv slight change in direction ventrally to extend the process. The suborbital process is much shorter than that shown by Scott (1940, fig. 120) for A. mortoni.
12 Fig. 4. Archaeotherium cf. mortoni. TMM 40840—1 5. Lateral view of skull and lower jaw. X .67 Fig. 5. Archaeotherium cf. mortoni. TMM 40840—15. Dorsal view of skull. X .67. Fig. 6. Archaeofherium cf. mortoni. TMM 40840—1 5. Ventral view of skull and jaw. X. 67. The PM 1 ,40283-95, is poorly preserved; its stratigraphic position in the Ash Spring l.f. and its size, slightly smaller than FMNH PM 98, of the Porvenir l.f. are the only items worth mentioning. Relationships.—Archaeotherium and Brachijlujops could well have come from a common ancestor, the former developing an elongate snout, the latter retaining a short snout. Although the dorsal part of the skull is incomplete at the posterior end, the preserved portion is similar to Brachijhyops except that the temporal open- ings are close together dorsallv and a saggital crest is formed. In the Texas specimen the frontals are raised above the orbits. From these elevations a rounded ridge extends in a posterior direction parallel to the midline and another rounded ridge extends posterolaterally above the orbit. Both rounded ridges end posteriorlv in a very pronounced ridge which forms the anterior and median rim of the temporal opening. The surface of the frontal between the rounded ridges has sculpturing, as shown in Colbert (1938, fig. 2), and so do the parietals between the midline and the rim of the temporal openings. At the frontal-parietal suture the dorsal width of the parietal is approximately 45 mm. Brachijhyops and Archaeotherium were contemporary forms during the early part of the Oligocene and may have had Eoentelodon as a common ancestor. This is the seventh in a series of papers relating to the stratigraphy and vertebrate faunas of the Vieja Group. Others are Wilson (1966), Hofer and Wilson (1967), Harris (1967), Wilson et al (1968), Harris and Wood (1969), and Wilson (1971). This publication is a contribution of the Verte- brate Paleontologv Laboratory, Texas Memorial Museum, The University of Texas at Austin,
REFERENCES Chow, Minchen, 1958, Eoentelodon—A new primitive entelodont from the Eocene of Lunan, Yunnan. Vertebrata Palasiatica, v. 2, no. 1, p. 30-34. Colbert, E. H., 1938, Brachijhyops, a new bunodont artiodactyl from Beaver Divide, Wyoming. Annals Carnegie Mus., v. 27, art. 4, p. 87-108. DeFord, R. K., 1958, Tertian Formations of Rim Rock Country, Presidio County, Trans- Pecos Texas. Texas Jour. Sci., v. 10, no. 1, p. 37. Gazin, C. L., 1955, A review of the Upper Eocene Artiodactyla of North America. Smith- sonian Misc. Collections, v. 128, no. 8, p. 96. , 1956, The geologv and vertebrate paleontology of upper Eocene strata in the northeastern part of the Wind River Basin, Wyoming, Part 2. The mammalian fauna of the Badwater Area. Smithsonian Misc. Collections, v. 131, no. 8, 35 p. Harris, ]. M., 1967, Toxotherium (Mammalia, Rhinocerotoidea) from western Jeff Davis Countv, Texas. Pearce-Sellards Ser. no. 9, Texas Memorial Museum, Austin, 7 p. Harris, J. M. and A. E. Wood, 1969, A new genus of eomyid rodent from the Oligocene Ash Spring local fauna of Trans-Pecos Texas. Pearce-Sellards Ser., no. 14, Texas Memorial Museum, Austin, 7 p.
16 Hofer, H. O. and J. A. Wilson, 1967, An endocranial cast of an early Oligocene primate. Folia Primat., v. 5, p. 148—152. Peterson, O. A., 1934, List of species and description of new material from Duchesne River Oligocene, Uinta Basin, Utah. Annals Carnegie Mus. v. 23, p. 373-389. Romer, A. S., 1966, Vertebrate Paleontology, Univ. Chicago Press, Chicago, 111., 468 p. Scott, W. 8., 1940, The mammalian fauna of the White River Oligocene, Part 4, Artio- dactyla. Amer. Phil. Soc. Trans., new series, v. 28, pt. iv. p. 363-746. , 1945, The Mammalia of the Duchesne River Oligocene. Amer. Phil. Soc., Trans., new series, v. 34, pt. 3, p. 209-253. Simpson, G. G., 1945, The principles of classification and a classification of the mammals. Amer. Mus. Xat. Hist. Bull., v. 85, 350 p. , 1946, The Duchesnean fauna and the Eocene-Oligocene boundary. Amer. Jour. Sci., v. 244, p. 52-57. Stovall, J. W., 1948, Chadron vertebrate fossils from below the Rim Rock of Presidio Countv, Texas Amer. Jour. Sci., v. 246, p. 78-95. Wilson, J. A., 1966, A new primate from the earliest Oligocene, preliminary report. Folia Primat., v. 4, p. 227-248. , 1971, Early Tertiarv Vertebrate Faunas, Vieja Group, Trans-Pecos Texas: Agriochoeridae and Mervcoidodontidae. Texas Memorial Museum, Bull. 18, 83 p. Wilson, J. A. and P. C. Twiss, R. K. DeFord, S. E Clabaugh, 1968, Stratigraphic succes- sion, potassium-argon dates and vertebrate faunas, Vieja Group, Rim Rock Country, Trans-Pecos Texas, Amer. jour. Sci., v. 266, p. 590-604. Wood, H. E. 11, 1948, Section at Beaver Divide, in Guidebook, 3rd Annual Field Con- ference Soc. Vert. Pal., S. E. Wyoming, p. 37-41. Wood, H. E. 11, et ah, 1941, Nomenclature and correlation of the North American con- tinental Tertiarv. Geol. Soc. America Bull., v. 52, p. 1-48.
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The Pearce-Sellards Series The Pearce-Sellards Series are occasional papers published by the Texas Me- morial Museum, 24th & Trinity, Austin, Texas. Other publications include the Bulletin series, Notes, and mimeographed information circulars. A complete list will be sent upon request. No. 1. Fossil Bears from Texas, by Bjorn Kurten, 1963 35 No. 2. Post-Pleistocene Raccoons from Central Texas and their Zoogeo- graphic Significance, bv Thomas Wright & Ernest Lundelius, Jr., 1963 40 No. 3. A New Fossil Tortoise from the Texas Miocene, by Walter Auffenberg, 1964 25 No. 4. The Osteology and Relationships of the Pliocene Ground Squir- rel Citellus clotti Hibbard, from Ogallala Formation of Bea- ver County, Oklahoma, by Margaret Skeels Stevens, 1966 75
No. 5. The Status of Bootherium brazosis 1966 . . . .25 , by Clayton E. Ray, No. 6. Geologic Reconnaissance of the Fort Davis National Historic Site, Texas, by Gordon Everett, 1967 35 No. 7. Mammalian Remains from Rattlesnake Cave, Kinney County, Texas, by Holmes A. Semken, 1967 35 No. 8. Development of Terminal Buds in Pinyon Pine and Douglas-fir Trees, by Charles L. Douglas & James A. Erdman, 1967 35 No. 9 . Toxotherium (Mammalia: Rhinocerotoidea) from Western Jeff Davis County, Texas, by John M. Harris, 1967 35 No. 10. New Brazilian Forms of Hijla, by Bertha Lutz, 1968 35
No. 11. Taxonomy of the Neotropical Hylidae, by Bertha Lutz, 1968 . . 35 No. 12. Geographic Variation in Brazilian Species of Hyla, by Bertha Lutz, 1968 35 No. 13. Remarks on the Geographic Distribution and Phyletic Trends of South American Toads, by Jose Cei, 1968 35 No. 14. A New Genus of Eomyid Rodent from the Oligocene Ash Spring Local Fauna of Trans-Pecos Texas, bv M. Harris & Albert ' John E. Wood 35 No. 15. New Early Miocene Formation and Vertebrate Local Fauna, Rig Bend National Park, Brewster County, Texas, By Margaret S. Stevens, James B. Stevens, & Mary R. Dawson 75 No. 16. New Fossil Rodents from the Early Oligocene Rancho Gaitan Local Fauna, Northeastern Chihuahua, Mexico, by Ismael Ferrusquia-Villafranca and Albert E. Wood, 1969 35