Mammals’ bodies outpaced their brains right after the dinosaurs died
Fossils show mammals’ brains and bodies did not balloon together, contrary to expectations
Arctocyon primaevus (skull shown) was a Paleocene mammal that lived shortly after the mass extinction event that killed off nonbird dinosaurs. A new analysis of mammal brain sizes before and after the extinction reveals that mammals’ body sizes increased quickly in the wake of the event, but brain sizes lagged.
Thierry Smith, Royal Belgian institute of Natural Sciences