News Fossils

Let’s learn about Tyrannosaurus rex

Many open questions remain about this iconic dinosaur’s appearance, speed, brainpower and more

a tyrannosaurus rex opens its mouth on a roar as it prowls a barren landscape

Tyrannosaurus rex truly was a fearsome predator in its time.

Warpaintcobra/iStock/Getty Images Plus

By Maria Temming

An iconic scene in the classic 1993 film Jurassic Park begins with water glasses shaking on a dashboard. The vibrations sending ripples through the water turn out to be the stomping steps of a huge Tyrannosaurus rex. After escaping its enclosure, the dinosaur lumbers out onto a road. There, it uses its jaws — lined with knife-sized teeth — to tear apart a car, trying to eat the terrified park visitors huddled inside.

This scene gets some things about T. rex right. But other aspects don’t quite match what paleontologists know about this famous dinosaur.

Let’s get the word “Jurassic” out of the way first. Despite the name of the park in the film, T. rex did not live in the Jurassic Period. (That was about 201 million to 145 million years ago.) T. rex lived about 68 million to 66 million years ago. That puts it firmly in the Cretaceous Period (145 million to 66 million years ago).

In its time, T. rex truly was a fearsome predator, stalking prey across what is now western North America. Fossils have shown that T. rex could grow up to 12 meters (40 feet) long and 3.6 meters (12 feet) high. (Some scientists suspect T. rex could have gotten even bigger.) It may have weighed as much as a large elephant.

What’s more, a T. rex’s jaws really were jaw-dropping in size. They could be about 1.2 meters (4 feet) long and filled with roughly 15-centimeter-long (6-inch-long) teeth. Its bite packed a force of more than 6 metric tons, which was enough to crush bones — and maybe even a car.

But Jurassic Park’s depiction of the T. rex maw may not have been quite right. The movie monster’s teeth were on full display, even when its mouth was closed. This is similar to the setup in modern crocodiles’ mouths. But recent evidence suggests that T. rex teeth — like those of modern Komodo dragons — were hidden behind lips.

Science also casts doubt on how fast T. rex ran in the movie. In another famous Jurassic Park scene, a sprinting T. rex keeps up with a speeding car. But calculations based on fossilized footprints show that T. rex could only run about 20 to 40 kilometers (12 to 25 miles) per hour. Recent experiments with birds — the only dinos alive today — suggest that those estimates may be off.

There are still many other open questions about possibly the most famous dinosaur of all. Yet scientists — including curious teens — continue to uncover new insights into the terrifying T. rex.

Want to know more? We’ve got some stories to get you started:

Analyze This: How big was the biggest T. rex? Only around 80 fossil Tyrannosaurus rex skeletons have been found. They probably don’t include the biggest T. rex that ever lived. (11/20/2024) Readability: 6.2

Just how brainy was a T. rex? A debate rages over how to count brain cells in dinosaurs. At issue: figuring out how these extinct animals likely behaved. (7/25/2024) Readability: 7.9

The secret to T. rex‘s incredible biting force is at last revealed The force of a T. rex bite was roughly 6 metric tons. A new study points to what’s behind that mighty force. (6/1/2021) Readability: 7.3

Tyrannosaurus rex is far from the only dinosaur to star in the Jurassic Park movies. How do the films’ portrayals of T. rex and other dinos stack up to science? A paleontologist explains.

Explore more

Scientists Say: Dinosaur

Scientists Say: Jurassic

What is a dinosaur?

Explainer: The age of dinosaurs

Dinosaurs are still alive. Today, we call them birds

T. rex may have hidden its teeth behind lips

T. rex pulverized bones with an incredible amount of force

Newfound fossil is not a teen T. rex but a whole new species

This big dino had tiny arms before T. rex made them cool

New clues about dino speed come from birds strutting through mud

Cool Jobs: Bringing paleontology to the people

Activities

Word find

Test your knowledge and flex your creativity with T. rex- and other dino-related activities from the American Museum of Natural History. Build your own T. rex or T. rex roar, solve a fossil puzzle or print off an age of the dinosaurs card game.  

Power Words

More About Power Words

birds: Warm-blooded dinosaurs with wings that first showed up at least 150 million years ago. Birds are jacketed in feathers and produce young from the eggs they deposit in some sort of nest. Most birds fly, but throughout history there have been the occasional species that don’t.

Cretaceous: A geologic time period that included the end of the Age of Dinosaurs. Spanning 145 million to 66 million years ago, it was a time when the whole planet had a relatively mild climate, with forests growing near both the North and South Poles. It marked the emergence of flowering plants and massive volcanic eruptions, which triggered big shifts in ocean ecosystems. And some regions cooled, leading dinosaurs there to adapt by evolving a coat of insulating feathers. Finally, it all came to an end 66 million years ago when a giant meteorite crashed into Earth, changing the global climate overnight. This wiped out all the dinosaurs (except those that would survive as birds), along with half of all plant and animal species.

dinosaur: A term that means terrible lizard. These reptiles emerged around 243 million years ago. All descended from egg-laying reptiles known as archosaurs. Their descendants eventually split into two lines. For many decades, they have been distinguished by their hips. The lizard-hipped line are believed to have led to the saurischians, such as two-footed theropods like T. rex and the lumbering four-footed Apatosaurus. A second line of so-called bird-hipped, or ornithischian dinosaurs, appears to have led to a widely differing group of animals that included the stegosaurs and duckbilled dinosaurs. Many large dinosaurs died out around 66 million years ago. But some saurischians lived on. They are now the birds we see today (and who have now evolved that so-called “bird-hipped” pelvis).

family: A taxonomic group consisting of at least one genus of organisms.

force: Some outside influence that can change the motion of an object, hold objects close to one another, or produce motion or stress in a stationary object.

fossil: Any preserved remains or traces of ancient life. There are many different types of fossils: The bones and other body parts of dinosaurs are called “body fossils.” Things like footprints are called “trace fossils.” Even specimens of dinosaur poop are fossils. The process of forming fossils is called fossilization.

insight: The ability to gain an accurate and deep understanding of a situation just by thinking about it, instead of working out a solution through experimentation.

Jurassic: Lasting from about 200 million to 145.5 million years ago, it’s the middle period of the Mesozoic Era. This was a time when dinosaurs were the dominant form of life on land.

paleontologist: A scientist who specializes in studying fossils, the remains of ancient organisms.

predator: (adjective: predatory) A creature that preys on other animals for most or all of its food.

prey: (n.) An organism hunted by another, often for food. (v.) To attack and eat another organism.

species: A group of similar organisms capable of producing offspring that can survive and reproduce.

tyrannosaur: A line of meat-eating dinosaurs that began during the late Jurassic Period, about 150 million years ago. These species persisted into the late Cretaceous Period, about 65 million years ago. The best known member of these species: the late Cretaceous’ Tyrannosaurus rex, a 12-meter (40 foot) long top predator of its time.

Tyrannosaurus rex: A top-predator dinosaur that roamed Earth during the late Cretaceous period. Adults could be 12 meters (40 feet) long.

About Maria Temming

Maria Temming is the Assistant Managing Editor at Science News Explores. She has bachelor's degrees in physics and English, and a master's in science writing.

More Stories from Science News Explores on Fossils

  1. Animals

    Chicago’s Rat Hole? Science concludes it’s likely not from a rat

    By Amanda Heidt
  2. Fossils

    Here’s why ammolite gems have a rainbow shimmer

    By Maria Temming
  3. Fossils

    Newfound fossil is not a teen T. rex but a whole new species

    By Carolyn Gramling
  4. Fossils

    Baby pterosaurs likely died in violent Jurassic storms

    By Carolyn Gramling
  5. Fossils

    Fossil teeth reveal some dinos were fussy eaters

    By Tom Metcalfe
  6. Fossils

    New clues about dino speed come from birds strutting through mud

    By Sofia Caetano Avritzer
  7. Life

    Fungi have been ‘zombifying’ insects for 99 million years

    By Sofia Caetano Avritzer
  8. Fossils

    North American rhinos once gathered in large, hippo-like herds

    By Jake Buehler