Five million years ago, immense predatory sharks patrolled the oceans. Their giant teeth — left behind in coastal sediments like spent bullets — inspired the 1843 name that has since become a household word: megalodon.
Despite the megatoothed shark’s fame, however, the megalodon’s exact size and shape have long been a bone of contention. Because shark skeletons are largely made of cartilage, they rarely fossilize, leaving researchers to make wildly varying estimates — anywhere from 35 to 60 feet — using shed teeth and comparisons with living relatives like mackerel sharks and the great white.