T. rex (short for Tyrannosaurus rex) was one of the largest and most powerful meat-eating dinosaurs that ever lived. It stood about 12 feet tall at the hip, stretched 40 feet from nose to tail, and had a massive skull filled with teeth the size of bananas. Each tooth had edges like a steak knife, perfect for tearing through flesh and crunching bone.

T. rex lived during the late Cretaceous period, about 68 to 66 million years ago, in what is now western North America. Despite its fearsome reputation, T. rex had surprisingly small arms that couldn't even reach its mouth, though scientists still debate what those arms were used for. Its powerful legs and long tail helped it balance while moving, and research suggests it could run faster than a human but not quite as fast as movies sometimes show.

The name means “tyrant lizard king” in Latin, and for good reason. T. rex was an apex predator, sitting at the top of its food chain. Scientists have found dozens of T. rex fossils, making it one of the best-studied dinosaurs. When you visit a natural history museum and see that enormous skeleton with the giant skull, you're probably looking at a T. rex, the dinosaur that captures people's imaginations more than almost any other.