Until recently, Tyrannosaurus rex was the biggest known carnivorous dinosaur; Giganotosaurus and Carcharodontosaurus are slightly bigger.

ANATOMY
Tyrannosaurus rex was a fierce predator that walked on two powerful legs. This meat-eater had a huge head with large, pointed, replaceable teeth and well-developed jaw muscles. It had tiny arms, each with two fingers. Each bird-like foot had three large toes, all equipped with claws (plus a little dewclaw). T. rex had a slim, stiff, pointed tail that provided balance and allowed quick turns while running. T. rex's neck was short and muscular. Its body was solidly built but its bones were hollow.

SIZE
Tyrannosaurus rex was up to 40 feet (12.4 m) long, about 15 to 20 feet (4.6 to 6 m) tall. The arms were only about 3 feet (1 m) long. Tyrannosaurus rex was roughly 5 to 7 tons in weight.

T. rex left footprints 1.55 feet (46 cm) long (although its feet were much longer, about 3.3 feet (1 m) long; T. rex, like other dinosaurs walked on its toes). It had a stride length of up to 12 to 15 feet (3.7-4.6 m). T. rex may have run at up to 15 mph (24 kph).

TEETH, JAWS, AND SKIN
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 over 9 inches (23 cm) long; one T. rex was found with 13 inch (33 cm) long teeth. T. rex could eat up to 500 pounds (230 kg) of meat and bones in one bite!

Tyrannosaurus rex had a wrap-around overbite; when T. rex closed its mouth, the upper parts of the lower jaw's teeth fit inside the upper teeth.

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."

HABITAT AND DISTRIBUTION
Tyrannosaurus rex probably lived in forests, where its prey (plant-eating dinosaurs) could find plenty of food. T. rex fossils have been found in western North America and Mongolia.

SENSES
Sight: T. rex had large visual lobes in its brain that processed visual information. T. rex also had depth perception (since both eyes faced forwards on the front of its skull, and not placed on the sides), but it was not the only dinosaur that had depth perception.

Smell: T. rex's brain had a very large area for processing odors.

TAIL
Tyrannosaurus had a stiff, pointed tail (like other
The rear part of the tail was stiffened by interlocking vertebral zygopophyses (interlocking bony structures projecting forwards and backwards from the neural arches, interlocking one vertebra into another).