Its taxonomy is also controversial, as some scientists consider Tarbosaurus bataar from Asia to be a second Tyrannosaurus species, while others maintain Tarbosaurus is a separate genus. The feeding habits, physiology, and potential speed of Tyrannosaurus rex are a few subjects of debate. The abundance of fossil material has allowed significant research into many aspects of its biology, including its life history and biomechanics. Soft tissue and proteins have been reported in at least one of these specimens. Specimens of Tyrannosaurus rex include some that are nearly complete skeletons. Most paleontologists today accept that Tyrannosaurus was both an active predator and a scavenger. The question of whether Tyrannosaurus was an apex predator or a pure scavenger was among the longest debates in paleontology. Some experts have suggested the dinosaur was primarily a scavenger. By far the largest carnivore in its environment, Tyrannosaurus rex was most likely an apex predator, preying upon hadrosaurs, juvenile armored herbivores like ceratopsians and ankylosaurs, and possibly sauropods. Although other theropods rivaled or exceeded Tyrannosaurus rex in size, it is still among the largest known land predators and is estimated to have exerted the strongest bite force among all terrestrial animals. rex could grow to lengths of over 12.4 m (40.7 ft), up to 3.66–3.96 m (12–13 ft) tall at the hips, and 8.87 metric tons (9.78 short tons) in body mass. The most complete specimen measures up to 12.3–12.4 m (40.4–40.7 ft) in length however, according to most modern estimates, T. Relative to its large and powerful hind limbs, the forelimbs of Tyrannosaurus were short but unusually powerful for their size, and they had two clawed digits. Like other tyrannosaurids, Tyrannosaurus was a bipedal carnivore with a massive skull balanced by a long, heavy tail. It was the last known member of the tyrannosaurids and among the last non- avian dinosaurs to exist before the Cretaceous–Paleogene extinction event. Fossils are found in a variety of rock formations dating to the Maastrichtian age of the Upper Cretaceous period, 68 to 66 million years ago. Tyrannosaurus had a much wider range than other tyrannosaurids.

It lived throughout what is now western North America, on what was then an island continent known as Laramidia. rex or colloquially T-Rex, is one of the best represented theropods.

The species Tyrannosaurus rex ( rex meaning 'king' in Latin), often called T. Tyrannosaurus is a genus of large theropod dinosaur. (Gilmore, 1946) Bakker, Williams & Currie, 1988 (Gilmore, 1946) Charig in Appleby, Charig, Cox, Kermack & Tarlo, 1967

Simple t rex skeleton drawing