A Transitional Mammalian Carnivore Community from the Paleogene–Neogene Boundary in Northern Kenya

ABSTRACT

The Paleogene–Neogene boundary is an important transitional time for the evolution of African fauna. Many taxa that evolved endemically in the Paleogene begin to wane in diversity, while new taxa, many of which will become exemplars of the modern African fauna, immigrate from Eurasia via newly opened terrestrial connections. The Paleogene–Neogene boundary is documented in the fossil record at Nakwai, in northern Kenya. Here we describe the mammalian carnivore fauna, which includes the earliest carnivoran records in Africa, and an interesting mix of Paleogene and Neogene hyaenodont taxa. The carnivoran fauna includes Jinomrefu lakwanza, gen. et sp. nov., the earliest barbourofelid in Africa, which has a transitional sabertooth morphology. An analysis of ecomorphological change in African mammalian carnivores across this boundary shows that hyaenodonts become more disparate in body size and more hypercarnivorous as they are displaced by invading carnivorans. This provides another test case for possible competition between carnivorans and hyaenodonts, a group that goes extinct in Africa and globally during the Neogene.

http://zoobank.org/urn:lsid:zoobank.org:pub:D803E9DB-B2F1-497D-B796-57BED91BC744

ACKNOWLEDGMENTS

Special thanks to E. Mbua, F. K. Manthi, M. Muungu, and R. Nyaboke of the National Museums of Kenya, A. Mugume and M. N. Rose of the Uganda Museum, H. Mocke of the Geological Survey of Namibia, and G. Gunnell at the Duke Primate Center for help in their collections. S. Cote, L. MacLatchy, and M. Pickford kindly provided access to material they collected. J. Kappelman provided locality dating information. E. Miller, L. Werdelin, M. Gebis, C. Hazlett, the REACH group, and the Van Valkenburgh lab provided discussion, data collection and logistical and emotional support. J. Meachen, M. Lewis, and M. Borths provided valuable reviews of the manuscript. We thank Amisha Gadani for help with figure creation and Olga Anatoli for assistance with the Swahili translation of Jinomrefu. We also thank members of the Nakwai field crews not mentioned above who helped collect these specimens, including M. Amele, M. Gutierrez, D. Reynoso, T. Spell, N. Tabor, E. Gierlowski-Kordesch, B. Jacobs, E. Kane, B. Kyongo, B. Lokol, B. Rasmussen, and J. Rehg. This research was partly funded by the American Philosophical Society.