Fossil evidence for earliest Neogene American faunal interchange: Boa (Serpentes, Boinae) from the early Miocene of Panama

ABSTRACT

Isolated precloacal vertebrae from the early to middle Miocene Gaillard Cut of Panama represent the first Central American fossil record of the extant boine snake Boa and constrain dispersal of the genus into Central America from South America as no younger than approximately 19.3 Ma. Boa from the Las Cascadas fossil assemblage and the Centenario Fauna represent the oldest record of terrestrial southern vertebrate immigration into Central America, and demonstrate American interchange by the earliest Neogene. Interchange of snakes precedes contiguous terrestrial connection between Central and South America by approximately 17 Ma, necessitating dispersal across an approximately 100 km wide marine strait. The biogeographic history of snakes across the Neotropics is distinct from the mammalian record, and indicates a more complicated assembly of New World vertebrate faunas than previously recognized.

ACKNOWLEDGMENTS

This research was made possible through the collaboration and funding of the Autoridad del Canal de Panama (ACP), the Mark Tupper Fellowship, Ricardo Perez S.A., the National Science Foundation grants EAR 0824299 and OISE 0966884, and the National Geographic Society. We thank the paleontology/geology team at Smithsonian Tropical Research Institution and UF for help with fieldwork. Support for collection and curation of fossils was provided by US NSF grants OISE 0638538 and EAR 0642528 and University of Florida 2007 Research Opportunity Fund to B. J. MacFadden, PI/PD. J.J.H. was supported by a NSERC Discovery Grant.

Handling editor: Paul Barrett