The Tyrannosaurus Rex, often abbreviated as T. rex, was a large carnivorous dinosaur that lived during the late Cretaceous period, around 68 to 66 million years ago. It was one of the largest land predators, measuring up to 40 feet long and standing about 12 feet tall at the hips. Its powerful jaws were filled with large, serrated teeth, capable of crushing bone. T. rex had strong hind limbs and relatively small forelimbs, which were not as useful for hunting. Fossils have been found primarily in North America, and it is one of the most well-known dinosaurs, often featured in popular culture, including movies like Jurassic Park.