Tyrannosaurus Rex (meaning "Tyrant lizard king") was a huge, fierce, meat-eating dinosaur that lived during the late Cretaceous period, about 85 to 65 million years ago. This theropod dinosaur probably lived in forests, where its prey (large, plant-eating dinosaurs) could find plenty of food. Tyrannosaurus rex was named by paleontologist Henry Fairfield Osborn in 1905.
Diet: T. rex ate large dinosaurs, like Triceratops. This is known because fossilized T. rex dung was found containing crushed Triceratops bones.
Anatomy: Tyrannosaurus rex was up to 40 feet (12.4 m) long, about 15 to 20 feet (4.6 to 6 m) tall, and it weighed roughly 5 to 7 tons. A biped, it walked on two long hind legs. It had very short arms that each had two clawed fingers. The bird-like hind feet each had three large toes, all equipped with claws. T. rex's jaws were up to 4 feet (1.2 m) long and had 50 to 60 thick, conical, bone-crunching teeth that were up to 9 inches (23 cm) long.
Fossils: Dozens of T. rex fossils have been found in western North America and Mongolia. Fossilized specimens of T. rex's rough, scaly skin have been found. It was bumpy, like an alligator's skin, and has been described as a "lightly pebbled skin." Fossilized footprints and fossilized dung have also been found.