Discover: Did giant sea lizard rule oceans 66M years ago?

Nicholas Longrich of the University of Bath led a study about a newly identified species of mosasaur they called Thalassotitan atrox (which means merciless sea giant) found in Morocco that had conical teeth like a killer whale. It was as big as an orca, too, at 30 feet.

Konishi told Discover that the specimen resembles another mosasaur called Prognathodon overtoni.

“The bulk of the features are basically found in this other species of mosasaur,” Konishi told Discover. “It’s just 10 million years older. The morphological consistency between the two mosasaurs likely implies just a continuation of that same kind of niche for Prognathodon.”

When it comes to the world's largest marine reptiles, location might not be as important a factor to identification, he said.

“They are large predators, ​and 10 million years would've given ample time for any large marine reptiles to achieve global distribution, keeping their original niche wherever they ended up,” he told Discover.

Konishi and UC graduate Alexander Willman and University of Alberta professor Michael Caldwell in 2021 identified an 18-foot-long mosasaur they called Ectenosaurus everhartorum after paleontologists Mike and Pamela Everhart. The mosasaur inhabited the Western Interior Seaway 80 million years ago in what is now western Kansas. 

Read the Discover story.

Featured image at top: The teeth of a mosasaur. Photo/Joseph Fuqua II/UC