There's a fascinating new clue to the giant megalodon's extinction

One of the most striking fossils around today are the jaws of the megalodon.

The extinct shark fossils are so big, one or two people can stand inside them. They're relics of a dominant predator that thrived some 20 million to 3.6 million years ago, a shark species that likely munched on whales and big fish. They grew around 50...