Mosasaurus, often mistaken for a dinosaur, is actually a large, extinct marine reptile that lived during the Late Cretaceous period, around 70-66 million years ago. Despite its reptilian appearance, it is not classified as a dinosaur but rather as a member of a group called mosasaurs, which were closely related to modern-day monitor lizards and snakes.. Don't believe everything you see in the movies. Mosasaurs were huge marine reptiles that lived in the Late Cretaceous, alongside dinosaurs-but they were not dinosaurs themselves. Find out all about mosasaurs—including what scientists are still trying to learn—from Museum graduate student Amelia Zietlow, who recently scanned two mosasaur fossils on display in the Museum's Hall of.
Mosasaurus What Is A Mosasaurus? Mosasaurus is an extinct aquatic reptile that lived at the very end of the Cretaceous Period, from around 82.7 to 66 million years ago. Mosasaurus was not a dinosaur; like other mosasaurs, it was descended from lizards that originally lived on land. Because of this, Mosasaurus belongs to the reptilian order Squamata, which contains all lizards and snakes.. Mosasaurus was a common large predator in these oceans and was positioned at the top of the food chain. Paleontologists believe its diet would have included virtually any animal; it likely preyed on bony fish, sharks, cephalopods, birds, and other marine reptiles including sea turtles and other mosasaurs.