Overview: Megalodon. It was the biggest predator to ever swim the oceans of the world. For 20 million years, this ferocious 50-ton shark with a 7-foot jaw and seven inch teeth terrorized the creatures of the seas from Australia to South America and the coasts of North America. Not even the giant whales of the time were safe from this apex predator. Now, nearly 2 million years after Megalodon disappeared from earth, scientists will rebuild this monster shark.