Difficulty: Challenger (Level 2)
You may know of the Tyrannosaurus rex. This dinosaur was a huge land predator, but it was not the only unfriendly “T. rex”. There was also a marine reptile called Tylosaurus rex, and it was just as big and fierce.
Tyrannosaurus rex roamed land that is now part of North America roughly 66 million years ago.
The Tylosaurus rex (see graphic) lived in a sea that once divided North America about 80 million years ago.
A genus is a group of different species that are closely related. For example, lions and tigers are from the same genus but are different species.
The Tylosaurus genus has been known for centuries. But the species Tylosaurus rex was only formally named this year.
The largest Tyrannosaurus rex specimen is nicknamed Sue. It is about 12.3 to 12.8 metres long. It is held at the Field Museum of Natural History in the US city of Chicago.
The largest Tylosaurus rex specimen is even longer. Its name is Bunker, and it is 13.2 metres long. It lives at the University of Kansas Natural History Museum.
“The skull alone is as long as I am tall – 5-foot-7 inches [1.7 metres],” Amelia Zietlow said.
She is a palaeontologist from the History Museum at the Castle in the US state of Wisconsin.
She is also the lead author of a study published in the Bulletin of the American Museum of Natural History.
Tylosaurus is a member of a group of marine reptiles called mosasaurs. The group evolved from lizards that lived on land. They became sea-living predators during the final 30 million years of the age of dinosaurs.
Today, the Tylosaurus rex’s closest living relatives are probably monitor lizards, such as the Komodo dragon in Indonesia.
It is the largest living lizard. It can grow up to three metres long and weigh up to 150kg.
