A pelagic paradox: the rise and fall of large animals with shells in the pelagic realm

In contrast to the benthos, where mineralized exoskeletons have proliferated and become increasing well protected over time, the pelagic realm shows first an increase, then a post-Cretaceous decline in large animals with shells. The pelagic realm therefore diverged from the benthos after the Cretaceous, and also shows a divergence within the realm between large and small organisms with respect to mineralization. This example illustrates a widespread phenomenon of phenotypic obsolescence through time.

Speaker: Geerat Vermeij, UC Davis