Carrying on regardless: the echinoid genus Cyclaster at the Cretaceous–Tertiary boundary

A taxonomic revision and subsequent cladistic analysis show that Maastrichtian and Palaeocene species of the genus Cyclaster are split into three clades. Members of all three are present before and after the Cretaceous-Tertiary boundary, demonstrating that the genus Cyclaster as a whole was unaffected by the crisis at the end of the Cretaceous. Unlike most spatangoids, Cyclaster has the characteristic crystallographic signature of a lecithotrophic larval stage. Further work on other groups will determine whether larval strategy affected survivorship at this time.