A prehistoric shark swishes through an ancient sea. The fish doesn’t know that it’s being watched from the dark depths below. Without warning, the shark is snatched by a set of massive jaws belonging to a 45-foot-long marine reptile. The lizardlike beast, known as Tylosauraus proriger, gulps down its snack, then sinks back into the darkness to stalk more unsuspecting prey.


Related to modern day snakes and monitor lizards, Tylosaurus proriger lived during the Cretaceous period about 85 million years ago. It dwelled in an ancient body of water called the Western Interior Seaway, which once cut through what is now North America. The reptile propelled itself through the water with its powerful, flat tail and steered with its four paddlelike flippers.

Tylosaurus proriger was one of the deadliest hunters of its time. It had a long snout and hinged jaws, which gave it a fearsome bite. Its mouth was lined with rows of cone-shaped, razor-sharp teeth. And this colossal creature was always ready to chow down.


As it glided along the sea, sometimes surfacing above the waves, Tylosaurus proriger snapped up fish, seabirds, and even other marine reptiles such as the over 10-foot-long plesiosaurus. Given that this big beast was about the length of a school bus, it's no wonder it had a monster-size appetite!

Tylosaurus Ali and Sean travel back 80 million years to check out Tylosaurus, a prehistoric reptile that lived in what is now Kansas. They find out about life underwater for this enormous creature and get an up-close look at the Tylosaurus’ extra set of teeth!