A community-level test of the Mesozoic marine revolution theory

The Mesozoic marine revolution theory postulates a causal connection between the Cretaceous radiations of durophagous predators and the decline of suspension-feeding echinoderms in shallow-water habitats. In order to test the temporal distribution of dense ophiuroid populations for such a decline, I present a method of calculating the expected distribution of populations or communities in different geologic timespans. This statistical null hypothesis may then be compared with data from the fossil record to draw paleoecological inferences. The model takes into account the relative lengths of time blocks, the decay of sedimentary rock, and changes in shallow sea area through time. Although mass extinctions did not cause the immediate disappearance of shallow-water “brittlestar beds,” brittlestar beds show a significant decline in the Early Cretaceous. Results of several studies suggest that predators were at least partially responsible for reducing the distribution of dense ophiuroid populations.