An analysis of the impacts of Cretaceous Oceanic Anoxic Events on global molluscan diversity dynamics

Oceanic Anoxic Events (OAEs) are contemporaneous with 11 of the 18 largest Phanerozoic extinction events, but the magnitude and selectivity of their paleoecological impact remains disputed. OAEs are associated with abrupt, rapid warming and increased CO2 flux to the atmosphere, thus insights from this study may clarify the impact of current anthropogenic climate change on the biosphere. We investigated the influence of the Late Cretaceous Bonarelli Event (OAE2; Cenomanian – Turonian stage boundary; ~ 94 Ma) on generic- and species-level molluscan diversity, extinction rates, and ecological turnover. Cenomanian – Turonian results were compared with changes across all Cretaceous stage boundaries, some of which are coincident with less severe OAEs. We found increased generic turnover, but not species-level turnover, associated with several Cretaceous OAEs. The absence of a species-level pattern may reflect species occurrence data that are too temporally coarse to robustly detect patterns. ...