BULLETIN OF THE FLORIDA STATE MUSEUM BIOLOGICAL SCIENCES Volume 14 Number 2 MIOCENE AND PLIOCENE ARTIODACTYLS, TEXAS GULF COSTAL PLAIN Thomas Hudson Patton /853 UNIVERSITY OF FLORIDA Gainesville 1969 Numbers of the BULLETIN OF THE FLORIDA STATE MUSEUM are pub- lished at irregular intervals. Volumes contain about 300 pages and are not necessarily completed in any one calendar year. W,WrER AuFFENBERG, Managing Editor OLIVER L. AUSTIN, Jn., Editor Consultant for this issue: DONALD E. SAVAGE Communications concerning purchase or exchange of the publication and all manuscripts should be addressed to the Managing Editor of the Bulletin, Florida State Museum, Seagle Building, Gainesville, Florida 32601. Published June 17, 1969 Price for this issue $1.50 MIOCENE AND PLIOCENE ARTIODACTYLS, TEXAS GULF COASTAL PLAIN THOMAS HUDSON PATTON1 SYNOPSIS: Describes 27 species of fossil artiodactyls from a series of vertically successive mammalian. assemblages in Miocene and Pliocene deposits of the Texas Gulf Coastal Plain and discusses their systematic positions. Among the new forms represented are two camel genera: Australocametus, the probable Aep!/cameZus ancestor, and Nothott/lopus, a very unusual member of the Proto- labis-Pliauchenia lineage. The Floridagulinae are now seen to have had a trans-Coastal Plain distribution extending in time from the middle Heming- fordian Garvin Gully Fauna through the Barstovian Cold Spring Fauna. The Gulf Coast species of the Synthetoceratinae are discussed and the phylogeny of the subfamily outlined. Evidence from this study indicates that the Gulf Coastal Plain constituted a distinct faunal province throughout most of the Tertiary. Whereas many striking similarities exist between the faunas of the Texas Coastal Plain and those of the Great Plains, several groups are true Gulf Coast autochthons. Others, which are distributed in both regions, contain species endemic to the Gulf Coastal Plain. The ages of the Texas Gulf Coastal Plain faunas are revised and correlated with those from the Great Plains. TABLE OF CONTENTS 116 ACKNOWLEDGMENTS ... 117 ABBREVIATIONS . 119 STRATIGRAPHY . 120 DISTINGUISHING CHARACTERISTICS OF THE FAUNAS 126 SYSTEMATIC DESCRIPTIONS 188 Order ARTIODACTYLA 184 Suborder TYLOPODA 184 Family Camelidae -. .. f84 Subfamily Aepycamelinae -.~~..-~.~~......-...-. 184 Subfamily Camelinae ...._............ 150 Subfamily Floridatragulinae __ 168 Suborder RUMINANTIA . 174 Infraorder TRACULINA - - - 174 Family Protoceratidae . 174 1Thomas Hudson Patton is Assistant Curator of fossil vertebrates at the Florida State Museum and Assistant Professor of Zoology at the UBiversity of Florida, Gainesville. His principal research is on Tertiary mammals of the Gulf Coastal Plain and fossil vertebrates of the West Indies. Manuscript received 12 June 1968. - Ed. Patton, Thomas Hudson. 1969. Miocene and Pliocene artiodactyls, Texas Gulf Coastal Plain. Bull. Florida State Mus., vol. 14, no. 2, pp. 115-226. 116 BULLETIN FLORIDA STATE MUSEUM Vol. 14 Subfamily Synthetoceratinae 174 Phylogeny of the Synthetoceratinae 190 Infraorder PECORA 198 Family Cervidae 193 Subfamily Palaeomerycinae 4... .... 198 Subfamily Dromomerycinae 197 Family Antilocapridae - _.. .. 200 Infraorder OREDONTA . 201 Family Merycoidodontidae . 201 Subfamily Ticholeptinae 201 Subfamily Merychyinae 204 AGE AND CORRELATION 205 SUMMARY AND CONCLUSIONS 217 LITERATURE CITED . 220 INTRODUCnON The Miocene sedimentary rocks along the Texas Coastal Plain provide a record of successive mammalian faunas unsurpassed any- where in the Gulf and Atlantic coastal provinces of North America. This is the only such record outside of western North America, and consequently affords a basis for a detailed comparison of faunas from the Coastal Plain with those from the Miocene and Pliocene deposits of the High Plains. A series of vertically successive mammalian assemblages of rela- tively short temporal span gives the paleontologist an opportunity to study and observe not only geographic changes or shifts in animal communities through time, but also to detect microevolutionary steps within the various groups represented. The combination of good stratigraphic control and increasingly clearer evolutionary line- ages provides the basis for a more complete reconstruction of zoogeographical patterns, faunal interchange, and paleoecology than is usually realized in faunal studies. It also facilitates biostratigraphic correlations between faunas of the Texas Coastal Plain and those else- where especially from the more widely known Great Plains deposits. Whereas the Texas faunas show many similarities to those from the Great Plains region in individual taxa, they differ substantially in rela- tive abundance of taxa and, partially, in their faunal associations. Some groups, for example the synthetocerines, which are only sparing- ly represented in the Great Plains deposits, are abundant in the Gulf Coastal Plain faunas and appear to have undergone most of their evolution in the Gulf region. As would be expected, some taxa appear earlier or persist longer in one area than in the other. Yet 1969 PATTON: TEXAS ARTIODACTYLS 117 on the whole a similarity exists between the faunas of the two regions, which is fortunate for interregional biostratigraphic correla- tion, as most of the geochronologic framework of the North American Tertiary is based on the rocks and fossil vetebrate faunas of the Great Plains. Whereas the Great Plains and the Texas Coastal Plain faunas each evolved under their own particular set of environmental conditions, whatever ecological barriers existed between the two regions must have been slight enough to allow a relatively free interchange of forms between them. Still, enough isolation, geo- graphic at least, existed between the faunas of the two regions to permit specific and greater differences to accumulate. Although vertebrate fossils of Miocene and Pliocene age have been known from the Texas Coastal Plain for nearly a century, the area has only recently been investigated in detail. As fossil remains are for the most part fragmentary and widely dispersed throughout these deposits, the area has been generaliy uninviting from both the collecting and systematic standpoints. Only when the unique nature of the faunal elements and their associations was recognized and its importance understood were any significant studies undertakeh. - Papers by Hay ( 1924) and Hesse ( 1943) included the Brst general faunal descriptions of fossil vertebrates from the Texas Coastal Plain. Quinn ( 1952, 1955) studied in detail the fossil horses from these faunas, and later Wilson ( 1957, 1960) described the entelodonts and the carnivores. Because of the unusually fortunate stratigraphic con- Bguration of the Coastal Plain faunas and the relative abundance of remaining undescribed fossil vertebrate material available, the writer undertook a systematic investigation of various artiodactyl groups. It is hoped that data derived from the study of these taxa may serve as a basis for further systematic and biostratigraphic analysis of the Texas faunas and will provide a foundation for reconstructing a sequence of biological events through time and also perhaps the geological and climatic processes that determined these events. ACKNOWLEDGMENTS I am indebted to John A. Wilson of the Department of Geology, the University of Texas, for his suggestions and criticisms during the writing of this paper. The critical reading of the manuscript by W. Charles Bell, Ernest L. Lundelius, and W. Frank Blair, of the University of Texas, by Donald D. Savage of the University of California ( Berkeley) and by Malcolm C. McKenna and Richard Tedford, American Museum of Natural History. is gratefully acknowledged. 118 BULLETIN FLORIDA STATE MUSEUM Vol. 14 I should also like to thank Malcolm C. McKenna, Morris F. Skinner, and my colleague S. David Webb of the Florida State Museum, the University of Florida, for numerous stimulating and enlightening discussions on the strati- graphy and fossil vertebrate faunas of the Tertiary of the western United State5. I am grateful to the Department of Geology of the University of Texas, the Coates Foundation of the University of Texas, The Society of the Sigma Xi and the Scientific Research Society of America, the Houston Geological Society, and to the Humble Oil and Refining Company for financial support during the course of this project I should like to express my appreciation to authorities at the American Museum of Natural History, the United States National Museum, the Museum of Comparative Zoology at Harvard University, Texas A&M University, the Shuler Museum of Paleontology at Southern Methodist University, the University of California Museum of Paleontology ( Berkeley), the Florida State Museum, and the Frick Laboratory of the American Museum of Natural History, for permitting me to examine fossil material under their care. Finally, I wish to express my deepest thanks to my wife, Ellen Frederick Patton, for her constant encouragement and indispensable support throughout the course of this work. The illustrations were drawn by Mrs. Margaret Skeels Stevens. ABBREVIATIONS 1 Materials belonging to various institutions are referred to in the text by their catalog numbers and the following abbreviations: AMNH American Museum of Natural History FAM Frick Collection, American Museum of Natural History FSGS Florida State Geological Survey MCZ Museum of Comparative Zoology, Harvard University SMU Southern Methodist University TAMU Texas A&M University UCMP University