Tylosaurus a species of Mosasaur

Tylosaurus was a species of Mosasaur. It was enormous, reaching more than 50 feet (15m) in length.
The tylosaurus was a meat eater with a very diverse diet. Stomach remains show signs of fish, sharks, smaller mosasaurs, plesiosaurs, and even some flightless birds.
 They lived during the late Cretaceous in the seas that covered North America, where they sat firmly atop the marine food chain for several million years.