Ecological selectivity of diet on turtle K/Pg survivorship

The Cretaceous/Palaeogene (K/Pg) mass extinction was catastrophic, eliminating much of terrestrial life and entire iconic vertebrate groups, such as non-avian dinosaurs and many large marine reptiles. Turtles, however, were one of the less affected reptilian groups, persisting into the Cenozoic with minimal diversity loss. Diet has been suggested to explain high turtle survivorship, as multiple K/Pg survivors exhibit durophagous adaptations, but this has never been properly tested. We use phylogenetic comparative methods to map durophagy across turtle evolution and statistically test a relationship between turtle survivorship and durophagy. Turtles evolved durophagy multiple times over the course of their history, and our results indicate that the number of durophage lineages was more stable across the K/Pg transition than that of non-durophages. Additionally, our findings show that durophagy is positively correlated with turtle K/Pg survivorship, whereby durophagous species exhibit higher predicted survival probabilities. As non-durophagous turtle lineages also survive, albeit with lower probability, other factors might also influence turtle survivorship. Overall, this study provides numerical evidence for dietary ecological selectivity among turtle survivors at the end-Cretaceous crisis. Future taxonomic assessments of the turtle fossil record around the K/Pg boundary will be key to refine these results.