Tyrannosaurus is a genus of tyrannosaurid theropod dinosaur. The species Tyrannosaurus rex (rex meaning "king" in Latin), often called T. rex or colloquially T-Rex, is one of the best represented of these large theropods. Tyrannosaurus lived throughout what is now western North America, on what was then an island continent known as Laramidia 68 to 66 million years ago. It was the last known member of the tyrannosaurids and among the last non-avian dinosaurs to exist before the Cretaceous–Paleogene extinction event.

Like other tyrannosaurids, Tyrannosaurus was a bipedal carnivore with a massive skull balanced by a long, heavy tail. 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. The most complete specimen measures up to 12.3 meters (40 feet) in length, and according to most modern estimates 6 metric tons (6.6 short tons) to 8 metric tons (8.8 short tons) in weight. 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.

The Devon Rex, the Cornish Rex and the Selkirk Rex are breeds of domestic cats. “Rex” cats have genetic mutations that give their fur a curly or wavy appearance. They are known for being talkative and very, very smart.

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