Fact-O-Matic: cretoxyrhina

The Tylosaurus was top predator of the underwater Cretaceous. Now here is what this extremely powerful, monstrous, killing machine evolved from: believe it or not it evolved from these super small lizards that were trying to escape the dinosaurs in the Jurassic. And the lizard's only defense was to escape into the water and eventually it evolved to be built for the water. And the creature evolution just made was called Dallasaurus. And when did it evolve? The early Cretaceous.

When the late Cretaceous came, which was the time all the dinosaurs died out probably because of an asteroid, Tylosaurus became a fearsome predator. Probably because of its little special weapon: its teeth. The teeth point back into the mouth, so the only way the prey can go to escape is into the Tylosaurus, but it is hard for it to go inside. It has roof mouth teeth so it can hold the prey in place. Now there are many different types of Tylosaurus, but all of them are related to the snake. The Tylosaurus' future relative is the snake.

Now not all Tylosaurus are the biggest of predators. There is a small one called Platecarpus. And what makes it strange is that it has webbed feet, rather than fins. But Tylosaurus had some fearsome rivals. Now one of them is called the Ginsu Shark, also known as Cretoxyrhina. But Tylosaurus thinks the Ginsu Shark is an easy meal, even though the Ginsu Shark is even bigger than the sharks of today. But here is a really, kind of easy to munch meal. It's called Tusoteuthis, an enormous squid, probably related to today's colossal squid. Another rival of the Tylosaurus is called Squalicorax, another shark. Probably not as big as the Ginsu Shark, but believe me, the Squalicorax is quite a predator.

(Photo from animals.nationalgeographic.com)