[Lee Stewart]

Basilosaurus swam through the ocean like a giant sea serpent from 37.8 million to 33.9 million years ago, with a slender body that stretched up to 59 feet (18 m) in length. The name Basilosaurus translates to "king lizard" because the researchers who named it mistook the gigantic life-form for a marine reptile, like a mosasaur or ichthyosaur. But the species wasn't a serpent or a lizard; it was a mammal, and a relative of modern whales, according to the University of Michigan's Museum of Paleontology.