Fossil teeth show how a mass extinction scrambled shark evolution
The dinosaur-destroying event flipped which sharks were most dominant in the oceans
The extinction event that wiped out all nonbird dinosaurs about 66 million years ago also shook up shark evolution.
Fossilized shark teeth show that the extinction marked a shift in the relative fates of two groups of sharks. Apex predators called lamniformes, which include modern great white sharks, dominated the oceans before the event, which took place at the end of the Cretaceous Period. But afterward, midlevel predator sharks called carcharhiniformes came to dominate the waters — as they still do today, researchers report August 2 in Current Biology.