The extinct shark species that was the largest ever known was Megalodon. Its scientific name, Otodus megalodon, means “big tooth,” an apt reference to its enormous fossil teeth.
Megalodon lived roughly 23 to 3.58 million years ago, from the Miocene into the Pliocene. Because sharks have skeletons made mostly of cartilage, their fossils are rare; scientists reconstruct its size and appearance mainly from teeth and a few vertebral remains. Estimates vary, but it was one of the most powerful marine predators in history.
Megalodon was not simply an oversized great white shark. It belonged to the extinct family Otodontidae, while great white sharks belong to Lamnidae. The two were distant relatives, not members of the same genus. Megalodon likely hunted whales and other large marine animals, and climate change, shrinking prey ranges, and competition may have contributed to its extinction.