Today’s whales, dolphins and porpoises can trace their ancestry to Archaeocetes, the name given to a group of prehistoric whales that lived 55 to 34 million years ago. However, these animals looked nothing like whales. Well I’m being overly dramatic; one looks kind of like a whale, but it not exactly.
Based on the drawings in the Encyclopedia of Marine Mammals, four out of five ancestors had feet (a couple had webbed feet) and one had flipper like appendages. One ancestor called the Ambulocetus had the body of a crocodile and a huge rat-like head. Maybe the name is derived from the word ambulance because if you ran into an Ambulocetus there’s a pretty good chance you would have to call 911.
One of the ancestors actually looks like an extra-large opossum. But instead of describing each ancient whale relative, the main take away message is that today’s whales descended from animals that lived on land and swam in the water. I suppose if whales tire of the ocean and ache to stand on hard ground, sometime down the road they may start developing legs again. Why not? It wouldn’t be the first time something like that has happened.