Think about how tall you are. Then imagine a creature with a head the size of your body, give or take a foot, with teeth capable of crushing a turtle shell. That's the Machimosaurus rex, an ancient sea-dwelling crocodile recently discovered by scientists in Tunisia, according to a report from the journal Cretaceous Research. It is the world's largest sea-dwelling crocodile discovered to date.

From giant head to terrifying tail, the M. rex was "almost the size of a school bus," lead author Federico Fanti told The Washington Post. It took scientists two days to uncover just the head of the M. rex, and once they did, they realized "the rest of the body was just lying there," Fanti said. Fun!

The discovery may prompt scientists to reconsider their earlier assumptions about mass extinction. The group of crocodiles that the M. rex would've belonged to was thought to have gone extinct 150 million years ago, but these findings suggest the M. rex was still stomping around just 130 million years ago.