Mosasaurs may have terrorized rivers as well as oceans

The Late Cretaceous apex predator easily grew to the size of a great white shark. Breakthroughs, discoveries, and DIY tips sent every weekday. Nearly 70 million years ago, mosasaurs were the stuff of nightmares. Multiple species of the apex marine reptiles lived during the Late Cretaceous, often growing anywhere from 30 to 40 feet-long. But as dangerous as the ancient, great white shark-sized were for their prehistoric ocean prey, paleontologists have long assumed mosasaurs stuck to saltwater.