Meeting Abstract
The paleoecology of lizards over time is largely unknown. This paucity of data is problematic for understanding lizard response to climate change, especially considering the climate change modern species are currently experiencing. Fortunately, Cenozoic hyperthermals represent comparable events to today’s perturbations, and many Paleogene deposits preserve squamate fossils. Inferring paleoecology has historically been based on form equaling function, correlating certain features with certain behaviors. Though this applies to certain taxa, there are many confounding examples. Stable isotope geochemistry, however, provides an independent test for several ecological parameters. We developed a novel method examining isotopic ratios in enamel as a proxy for ecology and applied it to lizards, providing new data testing the connection between squamate morphology, their diets, and the environments they occupy. We analyzed δ18O and δ13C ratios from tooth enamel in five extant lizard species. We found trophic separation in δ13C values, and indications of aridity through δ18O values. We applied this framework to extinct squamates from an Early Eocene herpetofaunal assemblage, where we identify xenosaurid and glyptosaurine squamates as well as alethinophidian snakes. The xenosaurid is one of the youngest representatives of Restes rugosus, and we provide the first testable hypothesis of its ecology. δ13C results indicate an insectivorous or carnivorous diet for both lizard taxa, representing the first hypothesis for the diet of R. rugosus. δ,18O results indicate a wet, warm environment, confirming prior hypotheses of a tropical community present in the Western Interior of North America in the Paleogene.
