Page 143 - Prehistoric Animals

Tile-O-Sorus

Tylosaurus

Tylosaurus (Knob lizard) is a genus of mosasaur*, which swam
the oceans in the Late Cretaceous, around 100 to 66 million years
ago. There are several species of the genus Tylosaurus and they vary
in size and weight, the largest have an average size of around 12 to 15
metres in length and weighing in around 7 tonnes. The smallest
measure around 5 to 7 meters in length and weigh in around 200 to
500 kilograms. Before and after it’s naming by Othniel Charles
Marsh, in 1872, many species added to the genus Tylosaurus have
since been moved to other genera. The result of this initial confusion
is older published lists of species belonging to the genus are much
longer than the shorter up to date published listings.

Tylosaurus was a very large marine reptile. It’s argued by
some, to have been the largest marine reptile to have ever inhabited
the oceans. Its large body was relatively thin and streamlined. It had
four large fins and a long lobed tail that could propel it through the
water at great speed. It had a large pointed head and huge jaws lined
with sharp cone shaped teeth. Its snout was rounded and fossils have
shown it was reinforce with bone. Fossils have also shown damage to
the snout that is believed to have been caused when Tylosaurus
rammed its prey. Being hit by an object several tons in weight would
have certainly disorientated its prey long enough for Tylosaurus to
grab the stunned animal in its huge jaws. Tylosaurus was a carnivore
and information gleaned from fossils has shown its prey consisted of
plesiosaurs, sharks, fish and even other Mosasaurs. Remains of dino-
saurs have also been found, suggesting Tylosaurus was eating the
dead bodies of animals that had drowned and sank to the seabed.

Tylosaurus is a mosasaur; mosasaurs being a genus containing
several groups or genera of similar marine reptiles. However, Tylo-
saurus is believed to be the first and earliest mosasaur. It’s also be-
lieved by some to be the largest marine reptile of these groups. Others
however, claim that honour should go to another group; Haino-
saurus. When a dispute or an unclear analogy is made relating to Ty-
losaurus it is the genus mosasaur that’s consulted for help, compari-
son and clarification, demonstrating how closely related these groups
are with one another and the possibility that they all had a single evo-
lutionary source. The disappearance of mosasaurs is also put down to
a single event and that is the Cretaceous–Paleogene extinction event.
This event was responsible for a large number of extinctions, the Mo-
sasaurs being just one of them.

*Mosasaurs (Meuse lizard) (Wikipedia)
Comprise a group of extinct, large marine reptiles from the Late Cretaceous.