T. rex was a big dinosaur that ate meat. It could be about 40 feet long and stand about 13 feet tall at the hips. A grown T. rex could weigh about six tons, like an elephant. It lived near the end of the time of the dinosaurs, more than 60 million years ago. Its name means "tyrant lizard king." Scientists think T. rex was not very fast, perhaps 10 to 20 miles an hour at its top speed.

T. rex had about 60 teeth, and a T. rex skull could be five feet long. As of May 2017, scientists put its bite at about 8,000 pounds of force, like three small cars pressing on its jaws, which was strong enough to crunch bones. T. rex ate large plant-eaters with thick bones, such as horned and duck-billed dinosaurs. It was a top predator in its world.

T. rex had a very good sense of smell, and its large eyes could see very well. A 2006 study found that T. rex had a binocular range of 55 degrees, wider than a modern hawk's, so both eyes saw the same space ahead. T. rex had very small arms for its big body, but its back legs were big and strong, with three toes.

T. rex grew very fast when it was a teenager. Dinosaur bones have growth rings, like trees, and scientists count the rings to tell how old a dinosaur was. By this count T. rex grew fastest between about age 14 and age 18. Sue stopped growing at about age 19 and died at age 28. Then a giant asteroid hit Earth about 66 million years ago, and T. rex and the other big dinosaurs died out.

Barnum Brown found two early T. rex skeletons, in 1900 and 1902. Sue is a famous T. rex skeleton that you can visit at the Field Museum in Chicago. It was found in South Dakota in 1990, and it is named after Sue Hendrickson, who found the skeleton. As of November 2026, Sue is one of the most complete T. rex skeletons ever found, about 90 percent complete. The skeleton is about 13 feet tall at the hip and more than 40 feet long.

As of August 2004, more than 30 T. rex skeletons had been found. As of March 2019, a T. rex nicknamed Scotty, found in Canada, was the largest T. rex known so far, and it weighed an estimated 19,400 to 19,600 pounds, about 8,800 kilograms. T. rex fossils have been found in western North America. Birds are modern-day dinosaurs, and a pigeon is a distant relative of T. rex.

Words to know

• predator: a hunting animal
• fossils: stone-like old remains
• binocular: using both eyes