Tyrannosaurus rex (T. rex)

Basic Information

Tyrannosaurus rex’s name means “Tyrant Lizard King” in Greek and Latin!

T. rex lived during the Late Cretaceous period, between 68 and 66 million years ago, right up until dinosaurs went extinct!

T. rex fossils have been found in western North America, from Canada down to New Mexico, showing they lived across a huge area!

The biggest T. rex ever found, nicknamed “Scotty,” weighed about 19,555 pounds (8,870 kg) — as much as three large elephants combined!

T. rex was one of the largest land carnivores (meat-eaters) of all time, reaching lengths of up to 40 feet (12 meters)!

Scientists have found about 50 T. rex specimens so far, with “Sue” being the most complete at 90% preserved!

T. rex belonged to a family of dinosaurs called theropods, which includes modern-day birds!

The most famous T. rex, “Sue,” was discovered in South Dakota in 1990 and sold for $8.4 million!

T. rex could probably run between 10–25 miles per hour (16–40 kilometers per hour), about as fast as a professional soccer player!

Scientists estimate there were about 20,000 T. rex alive at any given time during their existence!

Physical Features

T. rex had the strongest bite force of any land animal ever, with a bite force of about between 35,000 to 57,000 newtons (7,800 to 12,800 pounds-force) — strong enough to crush a car!

A T. rex tooth could grow up to 12 inches (30 centimeters) long, about the size of a banana!

T. rex had about 60 teeth, and could regrow lost teeth throughout its life, just like sharks do today!

T. rex’s arms were only about 3 feet (1 meter) long, but could probably lift around 400 pounds (181 kg) each!

T. rex’s eyes were about the size of oranges and faced forward like a hawk’s eyes, giving them excellent depth perception!

T. rex had a brain about the size of a loaf of bread, making it one of the smartest dinosaurs of its time!

Scientists think T. rex’s skin was covered in scales, similar to modern reptiles, not feathers like some of its relatives!

T. rex’s tail was about 40% of its total length and helped it balance while walking and running!

T. rex’s neck was short and S-shaped like a modern bird’s, allowing it to move its head quickly and precisely!

Hunting & Defense

T. rex could smell prey from several miles away, thanks to large areas in its skull dedicated to processing scent!

T. rex’s serrated teeth were designed to grip prey and strip meat from bones, working like steak knives!

T. rex might have hunted in family groups, as multiple T. rex fossils have been found near each other!

T. rex’s bite was so powerful it could crush bones like they were potato chips!

T. rex probably ate everything on its prey, including the bones, which provided extra nutrients!

T. rex had a special joint in its skull that absorbed shock while biting, preventing brain injury!

Habitat & Environment

T. rex lived in a warm, humid climate similar to today’s southern United States!

T. rex shared its environment with Triceratops, which was both its prey and neighbor!

T. rex lived in forests with giant redwood-like trees and primitive flowering plants!

T. rex inhabited coastal plains and river valleys, where prey was abundant!

T. rex lived during a time when flowers were just beginning to spread across Earth!

T. rex’s habitat experienced seasonal rainfall and occasional droughts, just like modern savannas!

T. rex lived alongside early mammals, which were mostly small and nocturnal (active at night)!

T. rex lived when the Earth was warmer than today, with no polar ice caps!

T. rex lived in all sorts of places — from lush, steamy jungles to dry, dusty deserts!

Discovery & Fossils

The first T. rex skeleton was discovered in Montana in 1902 by famous fossil hunter Barnum Brown!

Scientists can tell how old a T. rex was when it died by counting growth rings in its bones, like tree rings!

The largest T. rex skull ever found is 5 feet (1.5 meters) long — bigger than most kids are tall!

Scientists have found T. rex fossils with healed injuries, showing they could survive serious wounds!

Even teenage T. rexes were giants — 13–15 years old and already as long as a school bus!

Scientists have found T. rex teeth marks on Triceratops bones, proving they hunted these horned dinosaurs!

The most expensive T. rex fossil, “Stan,” sold for $31.8 million in 2020!

Some T. rex bones contain preserved protein molecules, teaching us about their biology!

Scientists recently discovered that T. rex had specialized nerve sensors in its jaws to feel its prey!