Paleobiologist Dr. Kenshu Shimada has been fascinated by fossil sharks, including the giant Otodus megalodon, since childhood — he found his first megalodon tooth at 13 years old. So when he saw ...

Turns out, the palm-sized tooth belonged to an animal that died at least 3.5 million years ago: an Otodus megalodon shark. "She told me she was wading in knee-deep water when she saw it and dove ...