20,000-pound mosasaurs ambushed prey with sneak attacks

Mosasaurs are terrifying enough based on their fossils alone. The Cretaceous marine reptile family encompassed some of the undisputed apex predators of Earth’s ancient oceans (and possibly even some rivers ). Species like Mosasaurus hoffmanii easily reached nearly 50 feet long, while weighing as much as 20,000 pounds—and there are many more mosasaurs just like them. So what could possibly make them any scarier? Some of the ancient aquatic hunters employed speedy, “slam-start” sneak attacks…