Tylosaurus

***Tylosaurus*** (name meaning "*Knob Lizard*") is a genus of large mosasaur that originated during the Late Cretaceous period in what is now North America. The apex predator of the Cretaceous seas, measuring 18 meters long, and weighing 17 tons, this marine reptilian monster of the deep was the largest mosasaur of all time, having nothing to fear but others of its own kind when fully grown.

In the Series 2 finale "***Death of a Dynasty I: To Hell's Aquarium... And Back?!***", a family group of Tylosaurus were brought to the park from Late Cretaceous Montana, 65 million years ago. They reside in the Marine Enclosure.

## Facts

### Era & Discovery

*Tylosaurus* lived during the Late Cretaceous period, around 87 – 65 million years ago. While *Tyrannosaurus* ruled over the land, *Tylosaurus* was at the top of the food chain in the Cretaceous seas. *Tylosaurus* died out alongside the dinosaurs during the K/T extinction. Though not a dinosaur, *Tylosaurus* lived at the same time and region as them and went extinct at around the same time at the end of the Cretaceous period. Since their first discovery in 1868, many *Tylosaurus* remains have been found in several different countries in North America. Additionally, they have also become one of the most famous prehistoric creatures in the world.

### Physical Attributes

The dominant marine carnivore of the Late Cretaceous seas, *Tylosaurus* was a giant predator that grew to reach more than 45 – 60 feet (13 – 18 m) in length and weighing 15 – 20 tons (33,000 – 44,000 lbs.), making it the largest of the mosasaur family of marine reptiles and one of the largest carnivorous animals the world had ever seen. Their serpentine shape was no accident, as they were close relatives of snakes. However, they were far more ferocious and even much larger. Smaller species lived in shallow waters close to shore. However, offshore in the deep oceans lurked true giants.

Like all mosasaurs, a long and muscular, vertically flattened tail powered *Tylosaurus* through the water, allowing it to ambush its prey with rapid bursts of acceleration. Paddle-like limbs helped steer the slim body covered in lizard-like scales through the water. Preserved stomach contents indicate a diet heavy on fish, but seabirds, sharks, plesiosaurs, and other mosasaurs also failed to escape *Tylosaurus'* lethal grip. These sea monsters were feeding on fish (*Xiphactinus* and sharks), sea birds (*Hesperornis*), and other reptiles (*Archelon*), plesiosaurs and other - smaller - species of mosasaurs, as well as other prey items. Its immense head size meant that it could have swallowed medium-sized animals like *Squalicorax* whole.

*Tylosaurus* was the deadliest hunter of the ancient seas, ready to seize and kill just about any creature that crossed its path with true jaws of death—lined on each side with two rows of pointy, cone-shaped teeth. *Tylosaurus* used its snout to locate prey, which, once inside the mosasaur's menacing jaws, was swallowed whole or torn to pieces. When the sea monster opened wide for the final gulp, two extra rows of teeth on the roof of its mouth allowed crippled captives no escape.

### Behavior & Traits

*Tylosaurus* was an immensely dangerous ocean predator, by far the most dangerous that ever lived on planet Earth in the Cretaceous seas. It hunted slow-moving prey like ammonites, birds, and turtles as well as larger creatures like sharks and *Elasmosaurus*. *Tylosaurus* was not the fastest of predators. Instead of chasing its prey, Tylo*saurus* would stalk and then it ambushed its prey in a short burst of speed. Being caught in its jaw meant almost certain death.

And if there was anything worse than swimming with these carnivorous sea reptiles, it would be swimming with its family. Interestingly, *Tylosaurus* lived and travel in groups of around 20 individuals to provide protection to their offspring. They attacked and ate virtually anything that moved – sharks, turtles, giant squid, even other members of its kind, making *Tylosaurus* a cannibal as well as a predator.