New early Miocene protoceratids (Mammalia, Artiodactyla) from Panama

ABSTRACT

Although Cenozoic protoceratid artiodactyls are known from throughout North America, species referred to the Miocene protoceratine Paratoceras are restricted to subtropical areas of the Gulf Coast and southern Mexico and tropical areas of Panama. Newly discovered fossils from the late Arikareean Lirio Norte Local Fauna, Panama Canal basin, include partial dentitions of a protoceratid remarkably similar to those of Paratoceras tedfordi from Mexico, suggesting a rapid early Miocene colonization of recently emerged tropical volcanic terrains (Las Cascadas Formation). Partial lower dentitions from the overlying shallow marine to transitional Culebra Formation (early Centenario Fauna) are here referred to Paratoceras orarius, sp. nov., based on relatively small size, shallow mandible anterior to p3, and narrow cheek teeth. New early Hemingfordian protoceratine fossils from the upper part of the Cucaracha Formation (late Centenario Fauna) include a partial male skull and several dentitions that, together with specimens previously referred to P. wardi (only known from the Barstovian of Texas), are here referred to Paratoceras coatesi, sp. nov., based on distinctly more gracile cranial ornamentation, relatively longer nasals, a smaller and wider lower p4 (relative to m1), and more bulbous lower premolars. Results from a cladistic analysis of 15 craniodental characters coded for 11 protoceratine species suggests that Paratoceras is a monophyletic clade with its origin in subtropical areas of Central America, spreading into the tropics of Panama during the early Miocene (Arikareean through Hemingfordian North American Land Mammal Ages [NALMAs]), and later inhabiting subtropical areas of the Gulf Coast during the middle–late Miocene (Barstovian through Clarendonian NALMAs).

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http://zoobank.org/urn:lsid:zoobank.org:pub:31FFF397-6362-443C-A612-E9279FF122

ACKNOWLEDGMENTS

We thank J. Bourque and D. Byerley at the FLMNH who prepared fossil specimens in the laboratory, and C. Montes, S. Suarez, M. Vallejo, and F. Moreno (STRI) and G. S. Morgan, A. Wood, J. Carr, S. Lukowski, D. Jones, J. Velez-Juarbe, and B. Newstead (PCP-PIRE) who helped collect the specimens. Special thanks to R. Hulbert Jr. (FLMNH) for help with anatomical terminology and taxonomic nomenclature. Thanks also to the AMNH staff for access to relevant fossil specimens, and K. Cummings, J. Pardo, and C. Byrd who edited an earlier version of the manuscript and made helpful comments for its improvement. Thanks to R. Emry and one anonymous reviewer for helpful reviews and comments that improved the quality of the manuscript. We also thank the Panama Canal Authority (ACP) and the Ministerio de Comercio e Industria (MICI) for access to relevant fossil sites and the UF Department of Geological Sciences for its support. This research was supported by UF Research Opportunity Grant; the U.S. National Science Foundation Partnerships in International Research and Education grant 0966884 (OISE, EAR, DRL), EAR 0824299, and EAR 0418042; National Science Foundation's Advancing Digitization of Biodiversity Collections Program (iDigBio) NSF EF 1115210; STRI-Tupper Paleontological Fund; STRI-Panama Canal Authority Fund; and Ricardo Perez Toyota, Panama. This is UF Contribution to Paleobiology number 660.