A new study shows the Megalodon, a gigantic shark that went extinct 3.6 million years ago, was more slender than earlier studies suggested. This finding changes scientists’ understanding of Megalodon behavior, ancient ocean life, and why the sharks went extinct.

Previous studies assume that the shark likely reached lengths of at least 50 feet and possibly as much as 65 feet. However, the Megalodon is largely known only from its teeth and vertebrae in the fossil record — a rather incomplete set of data from which to draw assumptions. Thus, the modern great white shark was traditionally used as a model for Megalodon bodies in previous studies. That model led researchers to conclude that the shark was round and stocky like great whites.

A revised understanding of the Megalodon body type would in turn affect scientists’ understanding not only of the giant shark itself, but also of its impact on the ecology and evolution of marine ecosystems that shaped the present-day oceans. There is no doubt the Megalodon is one of the largest marine predators ever to have lived. But a slimmer and more elongated body would suggest the Megalodon also had a longer digestive canal.