Mosasaurus

Mosasaurus was a large marine lizard that lived during the Late Cretaceous Period (70-66 million years ago) in shallow seas that covered what is now western Europe and North America. Mosasaurus was a top predator. A group of marine predators, the mosasaurs, are named after Mosasaurus.

History: The first Mosasaurus fossil was collected in 1764 in the Netherlands. Nothing like it had been seen before, and so the first people to examine it weren’t sure what it was - it was thought to be a fish, a whale, or possibly a crocodile. Eventually, paleontologists studied them more closely, and realized that these were fossils of an enormous lizard similar to modern monitor lizards.