Tyrannosaurus rex

Tyrannosaurus rex was a predatory dinosaur. This is probably the most famous and most fearsome predator of all times (Cretaceous, 85-65 million years ago), its name meaning 'terrible king lizard'. It is a very rare animal -- as of 2001 only 20 specimens are found, including only three complete skulls. This theropod dinosaur was first found by Barnum Brown, in the early 1900s.

T. rex could reach a length of up to 14 metres (45 feet) and could weigh up to 5 tonnes. Like all other therapods, T. rex had recurved teeth that ensured that meat was pulled free when biting their victims. All food was swallowed whole, since these dinosaurs never developed any chewing mechanism. T. rex had only its teeth as a weapon (in contrast to for instance raptors, who also used their toe claws). The arms of T. rex were exceptionally small, probably to make up for the weight of its enormous head.

Given the size of T. rex, and combined with the fact that they were almost certainly warm-blooded, paleontologist James Farlow calculated the number of lawyers a grown Tyrannosaurus had to eat (based on a scene from the movie Jurassic Park, in which a lawyer became T. rex fodder) to stay alive. Taken an average weight of 68 kilograms, 292 lawyers would be needed to keep one T. rex happy for a year!

The discussion about the feeding patterns of T. rex, and other large predatory dinosaurs hasn't finished yet. Some paleontologists called these dinosaurs 'Land sharks', and portrayed them as highly active predators, while others see them as scavengers. The available evidence of bite marks in other animals and even other T. rex, combined with the enormous serrated teeth and large jaw seem to speak in favour of a role as predator. Another theory is that their size and power allowed them to steal kills from smaller predators. Although not much is known about the vision of T. rex, the skulls clearly show that the eye sockets are positioned in such a way that they had binocular vision.

In contrast to common belief, T. rex was not the only Tyrannosaurus around. The following species have been identified:

(measurements given are based on found fossils and estimates)

T. torosus (Russel, 1970)

• Skull length : 1.1 m.
• Total length : 9 m.
• Hip height : 2.5 m.
• Weight : 2.3 tonnes

T. bataar (Maleev, 1955, in Mongolia)

• Skull length : 1.35 m.
• Total length : 10 m.
• Hip height : 2.9 m.
• Weight : 5 tonnes

T. rex (Osborne, 1905)

• Skull length : 1.75 m.
• Total length : 13.6 m.
• Hip height : 4.4 m.
• Weight : 12 tonnes

The classification of these varies a little (for instance, T. battaar is sometimes called Tarbosaurus).

Barnum Brown's T. rex fossil is now on display at the Carnegie Museum of Natural History in Pittsburgh, Pennsylvania.

The most complete and largest Tyrannosaurus rex fossil skeleton currently known, is exhibited at the Field Museum of Natural History

The Tyranosaurus rex is actually a member of the tyrannosaurids family of dinosaurs.

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Tyranosaurus Rex was also the original name of the 1970s pop group T. Rex founded by Marc Bolan.