| Named By: | Othniel Charles Marsh in 1872 |
| Time Period: | Late Cretaceous, 86.5-75 Ma |
| Location: | Canada. USA, particularly the central states |
| Size: | Up to 15 meters long |
| Diet: | Carnivore |
| Fossil(s): | Many Specimens as well as numerous teeth |
| Classification: | | Chordata | Reptilia | Squamata | Scleroglossa | Anguimorpha | Mosasauridae | Tylosaurinae | |
Tylosaurus (Greek tulos/tylos "protuberance, knob" + Greek sauros/sauros "lizard") was a mosasaur, a large, predatory marine lizard closely related to modern monitor lizards and to snakes.