The famous species Tyrannosaurus rex ('rex' meaning 'king' in Latin), commonly abbreviated to T.
The feeding habits, physiology and potential speed of T. Its taxonomy is also controversial, with some scientists considering Tarbosaurus bataar from Asia to represent a second species of Tyrannosaurus and others maintaining Tarbosaurus as a separate genus.
Several other genera of North American tyrannosaurids have also been synonymized with Tyrannosaurus.
Those in the upper jaw were larger than those in all but the rear of the lower jaw.
The largest found so far is estimated to have been 30 centimetres (12 in) long including the root when the animal was alive, making it the largest tooth of any carnivorous dinosaur.
Tyrannosaurus rex was one of the largest land carnivores of all time; the largest complete specimen, FMNH PR2081 ("Sue"), measured 12.8 metres (42 ft) long, and was 4.0 metres (13 ft) tall at the hips. rex formed a natural S-shaped curve like that of other theropods, but was short and muscular to support the massive head.
The forelimbs were long thought to bear only two digits, but there is an unpublished report of a third, vestigial digit in one specimen.
The tip of the upper jaw was U-shaped (most non-tyrannosauroid carnivores had V-shaped upper jaws), which increased the amount of tissue and bone a tyrannosaur could rip out with one bite, although it also increased the stresses on the front teeth.
The premaxillary teeth at the front of the upper jaw were closely packed, D-shaped in cross-section, had reinforcing ridges on the rear surface, were incisiform (their tips were chisel-like blades) and curved backwards.
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‘My mum came up to see me because of Sir Tom’, Olly said.
In contrast the hind limbs were among the longest in proportion to body size of any theropod.