Massive Fossil Study: End-Cretaceous Extinction's Impact on Sharks, Rays Varied

A massive trove of global fossil data has revealed variations in how elasmobranch species – sharks, skates, and rays – recovered after the Cretaceous-Paleogene (K-Pg) mass extinction event. Among the findings, species with restricted geographic ranges, as well as old shark species, show higher extinction rates. Understanding how elasmobranch species responded to past mass extinctions helps researchers identify the features of extinction victims and of extinction survivors. The Cretaceous-Paleogene (K-Pg) mass extinction event, which occurred roughly 66 million years ago, was Earth's last major extinction event and is estimated to have resulted in the removal of 55 to 76% of the planet's species. While the event drove drastic ecological changes in ecosystems worldwide, recent studies have suggested that the extinction patterns across the K-Pg boundary were complex and varied in severity between clades, ecologies, and geographical areas. However, studies involving extinction patterns among marine vertebrates are rare, meaning the end-Cretaceous extinction's impact on marine vertebrate diversity remains largely uncharacterized. To address this gap, Guillaume Guinot and Fabien Condamine compiled a global database of elasmobranch fossils representing 675 sharks, skate, and ray species spanning the Late Cretaceous-Paleogene interval. Their analysis revealed a significant loss of diversity following the K-Pg extinction; overall, elasmobranch species declined by more than 62% and did not fully recover in the Paleocene. However, the patterns of this extinction varied. According to the findings, rays and species that fed on shelled prey (durophagous), as well as more ancient shark species, reached the highest levels of extinction (more than 72%). Other sharks and nondurophagous species fared better and experienced a more rapid recovery following the extinction. Moreover, pelagic species with large geographic ranges and those restricted to higher latitudes also showed greater survival across the K-Pg boundary.