Tyrannosaurus – T-Rex

Tyrannosaurus Rex – The T-Rex: profile and facts about the king of the dinosaurs

The Tyrannosaurus Rex - usually simply called T-Rex - was one of the largest meat-eating dinosaurs to ever walk the earth. He lived around 68 to 66 million years ago at the end of the Cretaceous period, before an asteroid impact finally ended the era of the dinosaurs. With a length of up to 13 meters and a weight of almost nine tons, Tyrannosaurus Rex is still one of the largest land predators known to science. On this page you will find out how big and heavy the T-Rex really was, how strong its bite was, whether it actually had feathers and where its fossils were found.

Profile: Tyrannosaurus Rex

How big and how heavy was a Tyrannosaurus Rex?

An adult Tyrannosaurus Rex reached a body length of 12 to 13 meters and stood about 3.7 to 4 meters high at the hip. Paleontologists' estimates vary when it comes to weight,  because the body mass of a dinosaur can only be reconstructed indirectly using bone measurements. Most studies place the weight of an adult T-Rex between 6 and 8.8 tons.

The largest and heaviest specimen discovered to date is nicknamed “Scotty” and was recovered in Saskatchewan, Canada. According to the  Analysis by Scott Persons and his team at the University of Alberta Scotty weighed more than 8.8 tons during his lifetime - more than any other known land-dwelling carnivore in Earth's history. This meant that it even exceeded the “Sue” from Chicago, which was previously the record holder, by around 400 kilograms.

How strong was the Tyrannosaurus Rex bite?

The Tyrannosaurus Rex is considered the land animal with the strongest bite force ever measured. Using laser scans of the skull, researchers at the University of Liverpool and the University of Manchester calculated that  a single molar could generate forces of up to 57,000 Newtons. This corresponds to a weight of around 5.7 tons acting on a single tooth tip - for comparison: an adult human only has 700 to 1,000 Newtons when biting. This enormous power probably allowed the T-Rex to crush even the thick bones of its prey,  because Crushed pieces of bone have repeatedly been found in fossilized Tyrannosaurus feces.

How fast could Tyrannosaurus Rex run?

The T-Rex's top speed has been controversial among paleontologists for decades. Previous estimates were up to 53 km/h, while newer biomechanical models give significantly lower values. One  University of Manchester study reached a realistic top speed of around 19 km/h in 2017,  there faster movements would have overloaded the animal's leg bones. One  further analysis by researchers at the University of Maryland calculated a slightly higher value of around 27 km/h. A Tyrannosaurus was therefore designed for endurance rather than pure sprint speed.

Did Tyrannosaurus Rex have feathers or scales?

For a long time it was considered likely that Tyrannosaurus Rex also had feathers, because close relatives such as the Chinese Yutyrannus huali were demonstrably feathered - at around 1,500 kilograms it was even the largest known feathered dinosaur to date.

One  Investigation by Phil Bell and his team However, refuted this assumption for Tyrannosaurus. The researchers analyzed fossil skin impressions of Tyrannosaurus  as well as from related genera such as Albertosaurus, Gorgosaurus and Tarbosaurus and found exclusively small, scaly structures. Adult T-Rexes were therefore predominantly scaled, although their smaller ancestors still had feathers.

As an explanation, scientists suspect that large tyrannosaurids lost their feathers during evolution because a massive body stores heat better and an additional layer of insulation would have been more of a hindrance at this size. Feathers on individual, non-preserved parts of the body cannot be completely ruled out, but according to current research, a continuous plumage is considered unlikely.

Why did Tyrannosaurus Rex have such short arms?

Despite its impressive overall size, the T-Rex had noticeably short forearms that were barely longer than a human arm. Each arm ended in two clawed fingers that could have been used to hold onto prey. However, its arms did not reach its mouth, which is why Tyrannosaurus primarily grabbed its prey with its jaws. Then he tore pieces of meat from the bone with powerful neck muscles and quick, swinging head movements.

How old did a Tyrannosaurus Rex live?

Paleontologists estimate the age at which a dinosaur died based on growth rings in its fossil bones - similar to tree rings. Most Tyrannosaurus individuals studied lived to be 20 to 28 years old before dying. The oldest known specimen is “Scotty”, which, according to researchers at the University of Alberta, was around 30 years old. Since mortality was particularly high in the first year of life, less than half of all hatchlings survived their first year of life.

One published in January 2026 in the journal PeerJ  Growth Curve Revision by Holly Woodward, Nathan Myhrvold and Jack Horner also calls into question previous assumptions about the rate of growth: Based on 17 histologically examined individuals, the researchers come to the conclusion that Tyrannosaurus grew significantly slower than previously assumed and could not have reached its full body size until around 35 to 40 years old - around 15 years later than previous models assumed.

Where and when did Tyrannosaurus Rex live?

Tyrannosaurus Rex lived in western North America during the Late Cretaceous Period, about 68 to 66 million years ago. Fossils have so far been discovered primarily in what are now the US states of Montana, South Dakota, Wyoming and New Mexico, as well as in the Canadian provinces of Saskatchewan and Alberta. During its lifetime, the region was subtropical, with floodplains, swamps and open forests where Tyrannosaurus encountered herbivores such as Triceratops and Edmontosaurus. The habitat ended abruptly around 66 million years ago, when an asteroid hit the Yucatán Peninsula and triggered the mass extinction at the end of the Cretaceous period - which also caused the last Tyrannosaurus population to die out.

The discovery of Tyrannosaurus Rex

The first Tyrannosaurus rex skeleton was discovered in 1902 by Barnum Brown, a fossil hunter for the American Museum of Natural History. Brown came across the remains of a previously unknown large predator in the Hell Creek Formation in the US state of Montana.

Six years later, he found another, much more complete skeleton with an almost intact skull at Big Dry Creek in Montana. According to that  American Museum of Natural History This second find, cataloged as AMNH 5027, is still on display in the museum in New York today. The name Tyrannosaurus rex comes from the Greek word for “bully", the Greek word for "lizard“ and the Latin word for “king“ together and therefore means “King of the tyrant lizards“.

Tyrannosaurus Rex compared to other predatory dinosaurs

Even though Tyrannosaurus Rex is considered the best-known predatory dinosaur, it was not in every respect the largest carnivore in Earth's history. Spinosaurus, for example, is classified as longer according to current estimates, but weighed less and had a significantly lower bite force.

You can read more about Spinosaurus in our  Spinosaurus profile. Also the North African one  Carcharodontosaurus was one of the T-Rex's biggest competitors for the title of largest carnivore.

Tyrannosaurus rex in Jurassic Park, Jurassic World & Games

Hardly any other dinosaur is as present in pop culture as the Tyrannosaurus Rex. In the Jurassic Park and Jurassic World film series he appears as a recurring antagonist, whose stature and behavior differ significantly from current scientific findings - for example in the top speed shown in the film or the scaly, smooth skin without any trace of feathers on the neck or back. In survival games like ARK: Survival Evolved, Tyrannosaurus Rex can also be used as a tamable mount, making it one of the most sought-after dinosaurs in museums and films as well as in the gaming sector.

Frequently asked questions about Tyrannosaurus Rex

Sources: American Museum of Natural History, scinexx.de, National Geographic Deutschland, forschung.de, PeerJ (Woodward, Myhrvold & Horner, 2026).

Image sources: KoprX, CC BY-SA 4.0 https://creativecommons.org/licenses/by-sa/4.0, via Wikimedia Commons