Questions people actually ask
Short answers, each with its source. Longer ones live on the topic pages.
When was T. rex named?
Tyrannosaurus rex was named in 1905 by Henry Fairfield Osborn, president of the American Museum of Natural History. Wikipedia: Tyrannosaurus
What does Tyrannosaurus rex mean?
The name means “tyrant lizard king”: tyrannos is Greek for tyrant, sauros is Greek for lizard, and rex is Latin for king. Wikipedia: Tyrannosaurus
When did T. rex live?
Its fossils come from rocks dated to the end of the Cretaceous period, 69 to 66 million years ago. Wikipedia: Tyrannosaurus
Where did T. rex live?
It lived in what is now western North America, which was then an island continent called Laramidia. Wikipedia: Tyrannosaurus Its fossils have been found from Canada in the north to at least New Mexico in the south. Wikipedia: Tyrannosaurus
How big was T. rex?
Sue, one of the largest and most complete T. rex skeletons, measured 12.3–12.8 m long and 3.66–3.96 m tall at the hips. Wikipedia: Tyrannosaurus · checked 24 Oct 2026 Recent studies estimate the biggest adults at about 8.4 to 9.2 tonnes. Estimates have varied a lot over the years, from 4.5 tonnes to more than 7.2 tonnes, and most modern estimates fall between 5.4 and 8 tonnes. Wikipedia: Tyrannosaurus · checked 24 Oct 2026
How strong was its bite?
A 2012 study by Karl Bates and Peter Falkingham estimated that an adult T. rex could bite with 35,000 to 57,000 newtons of force at the back teeth, the most powerful bite of any land animal that has ever lived. Other studies give different figures. Wikipedia: Tyrannosaurus · checked 24 Oct 2026
Why were its arms so small?
Nobody knows for sure what the arms were for. Ideas include gripping a mate, helping it get up off the ground, and holding struggling prey. Wikipedia: Tyrannosaurus A 2022 paper by Kevin Padian suggested the arms got smaller so they would not be bitten off by other tyrannosaurs during group feeding. Wikipedia: Tyrannosaurus · checked 24 Oct 2026
Did T. rex have feathers?
A 2017 study concluded that if big tyrannosaurids like T. rex had feathers at all, they were limited to the top of the back. Wikipedia: Tyrannosaurus · checked 24 Oct 2026
How fast could T. rex run?
Estimates of T. rex’s top speed vary a lot: mostly around 9 metres per second (about 32 km/h), but as low as 4.5 m/s and as high as 20 m/s. Wikipedia: Tyrannosaurus · checked 24 Oct 2026 One 2017 study suggested an adult T. rex could not run at all, because speeds above about 18 km/h would have broken its leg bones. Wikipedia: Tyrannosaurus · checked 24 Oct 2026
Was T. rex a hunter or a scavenger?
Was T. rex a hunter or a scavenger? It was one of palaeontology’s longest debates. Most palaeontologists today accept it was a predator that would also scavenge when it could. Wikipedia: Tyrannosaurus · checked 24 Oct 2026
What is the most famous T. rex?
Sue was found on 12 August 1990 by fossil hunter Sue Hendrickson, and is named after her. Wikipedia: Sue (dinosaur) Sue is over 90% complete by bulk, about 250 bones. Wikipedia: Sue (dinosaur) · checked 24 Oct 2026
Are birds really dinosaurs?
Birds are the only living dinosaurs. They evolved from earlier theropods, the same big group T. rex belongs to. Wikipedia: Bird Birds are the only dinosaur lineage known to have survived. Wikipedia: Dinosaur
What killed T. rex?
About 66 million years ago a mass extinction wiped out three-quarters of plant and animal species on Earth, including all the non-avian dinosaurs. Wikipedia: Cretaceous–Paleogene extinction event It is generally thought to have been caused by an asteroid 10 to 15 km wide, which made the Chicxulub crater in Mexico. Wikipedia: Cretaceous–Paleogene extinction event
Sizes, masses, speeds and bite forces for T. rex are estimates from fossils, and different studies get different answers. Where we give a figure, the source link says which study and the date we checked it.