Mosasaurus was a giant marine reptile that lived near the end of the Late Cretaceous about 82 to 66 million years ago. Some species may have reached around 15 meters long which is about 50 feet. It was a powerful ambush hunter with a strong tail used for rapid bursts of speed and jaws lined with sharp teeth for gripping slippery prey. Elasmosaurus lived during the same general period but belonged to a completely different group of marine reptiles called plesiosaurs. It had an extremely long neck

Species Field Guide - Mosasaurus - Jurassic World Evolution 2