Do Plesiosaurs Still Exist?

All plesiosaurs became extinct as a result of the K-T event at the end of the Cretaceous period, approximately 66 million years ago.

What time period did plesiosaurs live in?

Plesiosaurs thrived during the Jurassic and Cretaceous. Some evolved into the short-necked, large-headed pliosaurs, such as the enormous Predator X. They died out 66 million years ago, along with the dinosaurs.

How did the mosasaurs go extinct?

During the last 20 million years of the Cretaceous period (Turonian–Maastrichtian ages), with the extinction of the ichthyosaurs and pliosaurs, mosasaurs became the dominant marine predators. They became extinct as a result of the K-Pg event at the end of the Cretaceous period, about 66 million years ago.