Tyrannosaurus (/tɨˌrænəˈsɔrəs/ or /taɪˌrænəˈsɔrəs/; meaning «tyrant lizard», from Greek tyrannos (τύραννος) meaning «tyrant,» and sauros(σαῦρος) meaning «lizard») is a genus of coelurosaurian theropod dinosaur. The species Tyrannosaurus rex (rex meaning «king» in Latin), commonly abbreviated to T. rex, is a fixture in popular culture. It lived throughout what is now western North America, at the time an island continent termed Laramidia, with a much wider range than other tyrannosaurids. Fossils are found in a variety of rock formations dating to theMaastrichtian age of the upper Cretaceous Period, 67 to 65.5 million years ago. It was among the last non-avian dinosaurs to exist before theCretaceous–Paleogene extinction event.
Like other tyrannosaurids, Tyrannosaurus was a bipedal carnivore with a massive skull balanced by a long, heavy tail. Relative to the large and powerful hindlimbs, Tyrannosaurus forelimbs were small, though unusually powerful for their size, and bore two clawed digits. Although other theropods rivaled or exceeded Tyrannosaurus rex in size, it was the largest known tyrannosaurid and one of the largest known land predators, the most complete specimen measuring up to 12.3 m (40 ft) in length, up to 4 metres (13 ft) tall at the hips, and up to 6.8 metric tons (7.5 short tons) in weight. By far the largest carnivore in its environment, Tyrannosaurus rex may have been an apex predator, preying upon hadrosaurs,ceratopsians, and possibly sauropods. although some experts have suggested it was primarily a scavenger. The debate over Tyrannosaurus as apex predator or scavenger is among the longest running in paleontology.
More than 30 specimens of Tyrannosaurus rex have been identified, some of which are nearly complete skeletons. Soft tissue and proteins have been reported in at least one of these specimens. The abundance of fossil material has allowed significant research into many aspects of its biology, including life history and biomechanics. The feeding habits, physiology and potential speed of Tyrannosaurus rex are a few subjects of debate. Its taxonomy is also controversial, with some scientists considering Tarbosaurus bataar from Asia to represent a second species ofTyrannosaurus and others maintaining Tarbosaurus as a separate genus. Several other genera of North American tyrannosaurids have also beensynonymized with Tyrannosaurus.