Research reviewed 30 July 2026. Scientific interpretations may change as new evidence is published.
Tyrannosaurus rex was a huge meat eating dinosaur that lived in western North America about 68 to 66 million years ago. Its fossils show a powerful predator and scavenger with bone crushing teeth, excellent senses and a body built for walking on two strong legs.
| Fact | Answer |
|---|---|
| Scientific name | Tyrannosaurus rex |
| Name meaning | Tyrant lizard king |
| Period | Late Cretaceous |
| Age | About 68 to 66 million years ago |
| Fossil locations | Western North America, especially the USA and Canada |
| Diet | Carnivore |
| Length | Commonly about 12 metres |
| Mass | Often estimated at 5 to 7 tonnes, with the largest known adults exceeding 8 tonnes |
Tyrannosaurus rex, usually shortened to T. rex, was one of the last non bird dinosaurs. It belonged to a group of two legged meat eaters called theropods. T. rex stands out because of its enormous skull, thick teeth, deep body and unusually powerful bite.
Henry Fairfield Osborn named the species in 1905. Its name means “tyrant lizard king”. Bone tissues and skeletons of different sizes have been used to study its growth, although the identity of some smaller tyrannosaur fossils is disputed.
T. rex lived near the end of the Late Cretaceous, about 68 to 66 million years ago. Fossils occur in rock formations across western North America, including Montana, Wyoming, the Dakotas and parts of Canada.
It shared these environments with Triceratops, Edmontosaurus, Ankylosaurus and smaller dinosaurs. T. rex disappeared during the mass extinction 66 million years ago, when all non bird dinosaurs died out.
A typical adult was around 12 metres long and stood roughly 3.5 to 4 metres high at the hips. Mass estimates often fall between 5 and 7 tonnes, although exceptional specimens such as Sue and Scotty were almost 13 metres long and may have exceeded 8 tonnes. Estimates change as researchers improve digital body models.
T. rex balanced its heavy head with a long, muscular tail. It walked with its back roughly horizontal, not upright with its tail dragging as older museum displays showed. Its two fingered arms were short but had strong muscle attachments. Their exact purpose remains uncertain.
Speed estimates also vary. Current biomechanical studies suggest that an adult was a capable walker but probably not a very fast runner.
T. rex was a carnivore. Its broad skull, strong neck and thick, serrated teeth allowed it to tear flesh and crack bone. Coprolites, which are fossilised droppings, contain crushed bone and show that it swallowed parts of its meals.
Tooth marks occur on Triceratops and Edmontosaurus fossils. One hadrosaur tail bone contains part of a T. rex tooth surrounded by healed bone. The animal survived long enough to heal, so the bite happened while it was alive. This is direct evidence that T. rex attacked living prey. Like most large predators, it would probably also have eaten an animal that was already dead.
Skeletons reveal how the body was built, while teeth and bite marks reveal feeding. Growth rings inside bones help researchers estimate age, but new studies continue to revise how quickly T. rex grew and how long it could live.
Skull spaces and casts of the braincase show large areas connected with smell. Forward facing eyes gave overlapping fields of view, which helped with judging distance. Skin impressions from several body regions show small scales. No direct T. rex feather fossil has been found, although some earlier tyrannosaur relatives had feathers.
Researchers continue to test how fast T. rex could move, how it used its arms and how much feathering it had at different ages. They also debate how often it hunted compared with scavenging. The evidence supports both behaviours, but fossils cannot provide a daily record of every meal.
Another question is whether young T. rex filled a different ecological role from adults. Some smaller tyrannosaur fossils are lighter, longer legged and have narrower teeth, but researchers now debate whether all of them are young T. rex or whether some belong to a separate genus called Nanotyrannus.
T. rex did not live in the Jurassic Period, and it did not need prey to move before it could see it. It was not simply a scavenger, because healed bite evidence shows an attack on living prey. Its tail was carried above the ground for balance rather than dragged behind it. The short arms were strongly muscled, but claiming one certain use goes beyond the evidence. It is also too definite to describe every T. rex as fully feathered or completely bare, because preserved skin covers only parts of the body.
The name means “tyrant lizard king”.
It lived about 68 to 66 million years ago, near the end of the Cretaceous Period.
They are found in western North America, particularly in the USA and Canada.
Many adults were about 12 metres long and weighed roughly 5 to 7 tonnes, but the largest known individuals were heavier.
It was probably both. A healed hadrosaur bone containing a broken T. rex tooth proves that it sometimes attacked living prey.
Its skull and teeth produced a bone crushing bite that was among the strongest known for a land animal.
Scientists do not yet know. The arms were short but strong, and several possible uses have been suggested.
Preserved skin shows scales in several areas, but other areas are unknown. No direct T. rex feather fossil has been discovered.
