When the whales first began, they were amphibious, crocodile-like creatures who lived in rainforests. A few million years later, whales evolved into something similar to their modern descendants. One such example is this creature: Basilosaurus. This animal was four times the size of a great white shark and ruled the oceans that existed after the dinosaurs. Their diet included smaller whales such as the dolphin-like Dorudon and any creature that was unfortunate enough to wander too far away from shore. Basilosaurus put the modern orcas to shame!