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The Sciences

The T. Rex Dined on Huge, Plant-Eating Dinosaurs — and Each Other

What was on the T. rex menu? These fearsome predators devoured massive herbivores, juvenile dinosaurs, and even engaged in cannibalism.

By Alex OrlandoMay 1, 2024 8:00 AM
Tyrannosaurus eats Triceratops © Witton 2022 (2)
This illustration by paleoartist Mark Witton shows a Tyrannosaurus rex devouring a Triceratops. (Credit: © Witton 2022)

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The fearsome Tyrannosaurus rex, the undisputed king of the Cretaceous, is easily the most famous dinosaur to have ever lived. Since its first fossil was unearthed in the late 1800s, T. rex has been immortalized in academic research, museums, and the public imagination.

If your diet of T. rex knowledge comes strictly from pop culture, though, you might come away with a skewed perspective on what these titanic predators ate. (In the first Jurassic Park film, it's seen chomping on a live goat, a rubber tire, and a cowardly lawyer.) Yet for decades, scientists have been turning to the fossil record to unearth more and more about the most well-studied dinosaur, including its feeding habits.

All of which begs the question: What did T. rex eat?

"Tyrannosaurs were hypercarnivores, meaning they ate meat and lots of it," says Darla Zelenitsky, a paleontologist at the University of Calgary. "Throughout its lifespan, a T. rex would have dined on a variety of other dinosaurs in the ecosystem."

By following the trail left by coprolite, or fossilized poop, as well as bite marks and fractures in the bones of other dinosaurs, paleontologists have dug up key details about how the T. rex chowed down.

What Did T. Rex Eat?

A fully-grown T. rex, says Zelenitsky, would have hunted down massive, plant-eating dinosaurs, including Triceratops or the duck-billed Edmontosaurus — both of which would have dwarfed modern-day animals like elephants.


Read More: The T. Rex Was More Like a Smart Crocodile, Instead of a Bright Baboon


Indeed, scientists studying T. rex coprolite found crushed bone fragments that likely came from an ornithischian (meaning bird-hipped) dinosaur like Edmontosaurus, according to a 1998 study published in Nature. Other researchers, meanwhile, identified T. rex bite marks on the fossilized pelvis of a Triceratops in a 1996 study in the Journal of Vertebrate Paleontology.

Fossilized stomach contents, however, tell a different story. "When I looked at stomach contents, the number one thing [I saw] was juvenile dinosaurs," says David Burnham, a paleontologist at the University of Kansas. "The big, bad T. rex ate babies. It's going to eat whatever it can catch."

What Younger Tyrannosaurs Ate

It wasn’t just adult T. rexes that devoured babies. Younger tyrannosaurs, in particular, likely targeted smaller prey, from lizards and crocodilians to other juvenile dinosaurs.

“Juvenile tyrannosaurs were mainly chasing down small and swift prey while the adults were hunting large herbivorous dinosaurs that lived in herds,” says Francois Therrien, curator of dinosaur paleontology at the Royal Tyrrell Museum. “The teenagers were agile, so they were able to hunt fast-running prey the size of a baby ostrich or turkey.”


Read More: This Tyrannosaur Devoured Dinosaur Babies Around 75 Million Years Ago


Recent research backs this up, too: In a 2023 study led by Therrien and Zelenitsky, an international team of scientists analyzed the fossilized stomach contents of a juvenile tyrannosaur — Gorgosaurus libratus, a close cousin of the T. rex — and found hind limbs belonging to two small dinosaurs, both of them under a year old.

“Prior to this study, we really did not know what was on the menu for teenage tyrannosaurs,” says Zelenitsky. “[This] is the first good evidence we have for what juvenile tyrannosaurs were eating.”

T. Rex Could Have Been a Picky Eater

With jaws capable of delivering a bite force of 57,000 newtons (or roughly 12,800 pounds), the T. rex was a powerful feeder that pulverized bone and flesh alike.

"The adult [tyrannosaurs], with their wide and large snouts, were bone crushers," says Therrien. "These animals would have been less discriminate feeders, ripping off and swallowing large chunks of flesh from their massive prey.”


Read More: The Tyrannosaurus rex May Have Had More Brains Than You Think


Still, fossil evidence suggests that T. rex ate with precision, as well. In a 2010 paper, paleontologists found that a Tarbosaurus, another close T. rex relative, used its jaws to carefully strip apart flesh from bone while scavenging a hadrosaur carcass.

More recently, in a 2021 study, paleontologists in Japan revealed that the T. rex may have even had a somewhat discerning palate: Thanks to a snout populated with sensitive nerve endings, it may have been able to differentiate between different parts of its prey to select the most nutritious morsels.

Was T. Rex a Cannibal?

It’s clear that T. rex was a fierce predator. Yet, like many modern predators, it was both an active hunter and an opportunistic scavenger who wouldn’t turn down a free meal if it came across carrion. And the aptly named “King of the Tyrant Lizards” wasn’t above dining on its own kind, either.

Several studies have found evidence that T. rex engaged in cannibalism. In 2010, paleontologist Nick Longrich and colleagues analyzed four T. rex bones and found deep tooth marks that could only have been made by other T. rexes.

Several years later, in 2015, paleontologists documented gouges left on a T. rex limb bone that came from a large predator with serrated teeth — once again marking another T. rex as the culprit, as the only carnivore around capable of inflicting such damage.

“Given that this behavior has a low preservation potential,” write the authors of the 2010 study, “cannibalism seems to have been a surprisingly common behavior in Tyrannosaurus.”

The king of the dinosaurs may have not been the only Cretaceous carnivore to prey on its own kin. While the practice hasn’t been extensively documented, paleontologists found evidence that Majungatholus atopus, a 30-foot-long therapod that roamed the plains of Madagascar 65 million years ago, also ate other members of its own species.


Read More: Almost 2 Billion T. Rexes Once Stomped the Earth


“It’s a type of ultra-cannibalism,” says Burnham. “When the predators become overpopulated, they start killing each other and eating each other. As T. rex became more powerful, it began reaching the limits of its capacity. It can kill and eat anything it wants. How long before they start turning on each other?”


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Alex is a senior associate editor at Discover. Before he joined the Discover team in 2019, he worked as a reporter for the Half Moon Bay Review and as a staff writer for Houston’s Texas Medical Center. His work has also appeared in The Verge and San Francisco Magazine. Alex holds a master's degree in journalism from UC Berkeley.

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