Basilosaurus
(Varies by Species)

Despite its name meaning "king lizard," Basilosaurus was no reptile — it was a whale, and one of the most formidable predators of its ancient ocean. It had a long, serpentine body stretching up to 20 meters and retained small, vestigial hind limbs. Fossil evidence suggests it was an active and aggressive predator that fed on large fish, sharks, and even other whales, with bite marks from its teeth found on the bones of its prey!