SELECTIVE SURVIVAL OF INFAUNAL DECAPODS OVER THE CENOMANIAN-TURONIAN OAE 2

Environmental stress from climate warming poses and has posed significant threats to marine organisms. Climate change-driven mass extinctions, such as the Cenomanian-Turonian ocean anoxic event (OAE 2) provide an opportunity to test impacts of warming and anoxia over evolutionary timescales. Past studies indicate that infaunal organisms sometimes, but not always, preferentially survived under climate-based mass extinctions, perhaps because infauna and semi-infauna have physiological, morphological and behavioral adaptations that help them tolerate hypoxia. Thus, I hypothesize that infaunal and semi-infaunal decapods will have lower rates of extinction in OAE 2 compared with epifaunal decapods. We compiled a record of Cretaceous and Paleogene decapods from the literature using the Paleobiology Database and assigned life habit on the family level as epifaunal, infaunal, or semi-infaunal. Preliminary data indicate a lower rate of extinction throughout the late Cretaceous and Paleogene in infaunal decapods as compared to epifaunal decapods. Extinction rates in semi-infaunal decapods as compared to epifaunal decapods were roughly equivalent through OAE 2, and after the OAE, semi-infaunal extinction rates became higher than epifaunal rates toward the end Cretaceous. However, these patterns may be complicated by differences in taxonomic practice. Infaunal decapods are mainly known from their first cheliped, which does not change much over evolutionary time. This conservatism may lead to lumping and overestimation of duration, which leads to underestimation of extinction rate. The magnitude of bias is unclear, but data is consistent with preferential survival of infauna during a climate change-driven mass extinction.