Late Cretaceous



Type of Animal

Sea Reptile


18 metres


20 tons

Top Speed

40 mph (64 km/h)

Bite Force

3 Metric Tons (4000 lbs)


Sharks, such as Squalicorax


Sea Monsters: to Hell...And Back? (Only Appearance)

Tylosaurus, AKA Giant Mosasaur was the largest mosasaur of all time. This monster of the deep would have had nothing to fear but others of its own kind when fully grown - they could eat giant fish,sharks, giant squid, giant turtles, Plesiosaurs, other Mosasaurs, Hespironis, and practically anything they could get their jaws around.


These fierce predators size average is about 60 feet.

Walking with DinosaursEdit

Tylosaurus was not in the main Walking with Dinosaurs series.


Sea Monsters Episode 3: To Hell...And Back?Edit


Tylosaurus in Sea Monsters

Tylosaurus featured in Sea Monsters: A Walking with Dinosaurs Trilogy. It was located in The Most Dangerous Sea Ever, along with other animals like Elasmosaurus, Xiphactinus, Hesperornis and Archelon, along with the equally vicious predators on land, including T. rex.  During the end credits, Nigel Marven's radar picks up a mob of Tylosaurus, who're preparing to attack the ship. We don't know if Nigel and his crew were eaten or not.

The thing that makes these animals so dangerous, is their adaptation for grouping behaviour - forming 'murders' (much like 'murders of crows') to provide protection for their vulnerable offspring in what were in fairness the worlds most deadliest seas of all time. However, for anything else living around them out in the open oceans, this defensive adaptation peversely turned the murders of Tylosaurus into mobile hunter-killer fleets; hence the term, 'murders' for their groups of individuals instead of just saying pod, pack or herd. The point is, you won't be 'lucky' enough to bump into just one 100 foot serpentine killing machine if you do so, you will be truly unlucky enough to bump into him and 60 or so of his friends. A terrifying force of nature no doubt, that ensured that even giant sharks, giant squid, huge killer fish and other (relatively) smaller mosasaurs wouldn't even dare to come near their babies.

Mosasaurus(19m) was nearly more bigger than Tylosaurus(18m)


  • Tylosaurus was identified as a Giant Mosasaur in the TV Series, which it sort of is.
  • In the opening of Sea Monsters, it shows Tylosaurus kill a Xiphactinus, but this is not shown in the actual story but it said the Xiphactinus suddenly dissappered after Nigel spotted it when he was on a Archelon so it is presumed it was deleted due to time.
  • Tylosaurus is the most dangerous pack predator of all time.
  • Tylosaurus is the second top predator to hurt Nigel Marvin, when he toppled the boat over. The first was Megalodon who knocked Nigel off the Ancient Mariner.
  • Tylosaurus is the second most dangerous predator of all time, beside humans. The third being Megalodon.
  • Tylosaurus is known to drive Cretoxhyrina, a prehistoric shark, to extinction via competition.
  • The Tylosaurus' species wasn't revealed in the epiosde where it appeared, but due to the place where we see it, plus the timescale, it is very probable that the species is Tylosaurus proiger, the biggest carnivore that ever lived.