Profile view of Tylosaurus pembinensis
Kingdom Animalia
Phylum Chordata
Superclass Tetrapoda
Class Reptilia
Subclass Diapsida
Order Squamata
Superfamily Mosasauroidea
Family Mosasauridae
Subfamily Tylosaurinae
Genus Tylosaurus
1st Species Tylosaurus proriger
2nd Species Tylosaurus nepaeolicus
3rd Species Tylosaurus pembinensis
4th Species Tylosaurus bernardi
Other attributes
Time Range 86.5-68 mya
Location United States of America, Canada, Belgium, Sweden, France, United Kingdom, Poland
Name Meaning Knob reptile
Physical Dimensions 12.2 meters long for T.proriger, T.pembinensis, and T.bernardi
Weight 5.6 tonnes for T.proriger, T.pembinensis, and T.bernardi
Dietary Classification Carnivore
Tylosaurus is a mosasaurid squamate reptile from the Late Cretaceous of the United States of America, Canada, Belgium, Sweden, France, the United Kingdom, and Poland. It was named in 1872 by Othniel Charles Marsh. It is one of the most studied mosasaurs, and it was a prominent aquatic apex predator for the time it inhabited the Earth.


Tylosaurus was a marine lizard with an elongated, streamlined body, 4 flippers, (likely) a long tail with a shark-like fin on its end, and a long, conical head with a mouth containing 2 rows of massive, conical teeth. Perhaps the most defining trait of this reptile was the extended bony knob on the tip of its snout, hence the meaning of its name, "knob reptile". Its body would have been covered in scaly skin.


Tylosaurus was a predator, preying on fish, cephalopods, turtles, diving birds, plesiosaurs, pterosaurs, and smaller mosasaurs. Its teeth had knife-like serrations from front to back, and were used to cut into the hides of large prey; as well as this, behind its huge jaws, it had a second set of teeth, mainly for capturing prey and ensuring it did not escape.


Tylosaurus was the apex predator of the Cretaceous seas it inhabited at the time, preying on any smaller animals it could find; bones of small plesiosaurs and diving birds have been found in its stomach cavity. In fact, it is also known to have attacked and preyed on smaller mosasaurs (perhaps being cannibalistic in extension), as fossilized skulls of smaller Tylosaurus had bite marks attributed to larger Tylosaurus, some of which were deep and did not heal. Tylosaurus' snout ended in a cylindrical knob, whose function remains open to debate, with some speculating that it may have been used for ramming into prey or intra-specific combat; neither prevalent theory seems to be especially likely, as mosasaur skulls are not built for taking heavy blows, and Tylosaurus most likely fought with other members of its species via face-biting. Finally, the diamond-shaped, keeled, snake-like scales on Tylosaurus' body would have cut the water around it as it moved, allowing it to swim faster.

In popular cultureEdit

Tylosaurus was first introduced to the public in the Rite of Spring segment of the 1940 Disney musical movie, Fantasia, where it jumps out of the water to snatch a Pteranodon flying overhead. Since then, it has appeared in many major pieces of media such as Chased by Sea Monsters, Sea Monsters: A Prehistoric Adventure, Monsters Resurrected, and Dinosaur Revolution; due to its many appearances in the media, it had overshadowed its close relative, Mosasaurus, for a while.

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