New record of aquatic snakes (Squamata, Palaeophiidae) from the Paleocene of South America

ABSTRACT

The Paleocene deposits from the Cerrejón Formation (Colombia, South America) have provided abundant snake remains. All this material has been assigned to the giant snake Titanoboa cerrejonensis. Here, we describe six vertebrae from among the referred materials that do not correspond to Titanoboa. All six vertebrae are morphologically identical, of a similar size, and display a distinct morphology that differs from Titanoboa. This new and unnamed taxon is a large snake estimated to be around eight meters in total length. Anatomical comparisons show that these vertebrae possess certain features typical of the Palaeophiidae, a group of extinct snakes of uncertain relationships known almost exclusively from vertebrae. Among the Palaeophiidae, the new taxon resembles the more generalized forms assigned to the genus Palaeophis, but lacks the extreme aquatic adaptations that define forms assigned to the genus Pterosphenus. We regard the new taxon as an undetermined palaeophiine but do not assign it to Palaeophis as a number of features differ from that described genus. This new record expands the known diversity of aquatic snakes from the Paleogene of South America and provides a substantial new record for the paleogeographic distribution of the Palaeophiidae. The oldest records are from the Cretaceous of Africa, while Paleocene records are poorly known and restricted to Africa, North America, and Europe. The majority of vertebral forms assigned to Palaeophiidae are from the Eocene, principally from the Tethys region, with only one previous South American record coming from the Eocene of Ecuador.

DISCLOSURE STATEMENT

No potential conflict of interest was reported by the author(s).

ACKNOWLEDGMENTS

Special thanks to M. Gomez-Perez and collections personnel of the IGM at the Servicio Geológico Colombiano (SGC). We also thank J. Luque for the help during the collections visit in Bogotá, and A. LeBlanc for assisting with photographs. We are also grateful to the Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET) of Argentina for support. Thanks are extended to two anonymous reviewers and the handling editor H. Yi. This work was partially funded by an NSERC Discovery Grant #23458 to MWC.

AUTHOR CONTRIBUTIONS

FFG, conceptualization, formal analysis, investigation, visualization, writing—original draft, writing—review and editing; ROG, formal analysis, investigation, visualization, writing—review and editing; MWC, conceptualization, funding acquisition, investigation, writing—review and editing.