Mosasaurs and Dinosaurs

The Dinosaurs emerged in the Triassic period. They were particularly numerous in the Jurassic and Cretaceous periods. At the end of the Cretaceous period, most Dinosaurs became extinct due to a large meteorite impact in Mexico.  Only the flying dinosaurs survived, and today's birds are descended from them. Mosasaurs do not formally belong to the dinosaurs, but they were the top predators of the sea.