The megalodon went extinct 3.6 million years ago, and is thought to be the largest shark that ever swam the Earth. But the megalodon may not have been as big as once thought, some researchers suggest.

Megalodon lived. Past tense. The largest shark ever, and arguably the largest predator, went extinct 2.6 million or more years ago. And it has stayed that way. But Hollywood sequel makers will be ...