Daily Dose of Prehistory: Back from Extinction 61

Basilosaurus cetoides, meaning "King Lizard", is a genus of extinct cetacean that existed during the Late Eocene, approximately 40 to 35 million years ago. Originally thought to be a gigantic reptile, it was later discovered to be an early whale. Measuring up to 59 feet long, it was one of the largest animals to exist after the KT extinction event some 26 million years earlier until modern cetaceans began to reach massive sizes around 15 million years ago. Unlike modern whales, Basilosaurus has a long, snake-like body and vestigial hind limbs, hints at the legacy of the animal's terrestrial ancestors. Having a smaller brain and lacking a melon organ, it would've also lacked the social nature of its modern relatives as well as their echolocation abilities. The type species (aka the first species discovered), Basilosaurus cetoides is the state fossil of the American states of Alabama and Mississippi.