The fearsome Tyrannosaurus rex, the undisputed king of the Cretaceous, is easily the most famous dinosaur that ever lived.
Since its first fossil was discovered at the end of the 19th century, it has been immortalized in academic research, museums and the public's imagination.
For decades, paleontologists have turned to the fossil record to discover everything, and its opposite, about the best-studied dinosaur - including its eating habits.
BBC Newsround
Well, what did T. rex eat anyway?
"Tyrannosaurs were hypercarnivores, which means they ate meat. A lot of meat," explains Darla Zelenitsky, a paleontologist at the University of Calgary in Canada, to Discover Magazine. "Throughout its life, a T. rex would have eaten a variety of other dinosaurs in the ecosystem."
By following the trail left by the fossilized remains of T. rex feces, as well as bite marks and fractures in the bones of other dinosaurs, the paleontologists unearthed important details about how the T. rex fed.
An adult T. rex, says Zelenitsky, would have hunted huge herbivorous dinosaurs, such as Triceratops or Edmontosaurus - creatures capable of putting a contemporary elephant in its pocket.
In a study published in 1998 in the journal Nature, the researchers found fragments of crushed bones in these fossilized remains that would have belonged to an ornithischian (i.e. duck-billed) dinosaur like Edmontosaurus.
Alex Orlando
Another study, published in 1996 in the Journal of Vertebrate Paleontology, identified T. rex bite marks on the fossilized pelvis of a Triceratops.
The fossilized stomach contents, however, tell a different story. "When I looked at the contents of the stomach, the first thing I saw were juvenile dinosaurs," paleontologist David Burnham, a researcher at the University of Kansas, told us. "The big, bad T. rex ate babies. It would eat anything it could get its hands on."
What the youngsters ate
It wasn't just adult T. rex that devoured babies. The younger tyrannosaurs targeted smaller prey, from crocodilian reptiles to other juvenile dinosaurs.
"Juvenile tyrannosaurs mainly chased small, fast prey, while adults hunted large herbivorous dinosaurs that lived in herds," says François Therrien, curator of dinosaur paleontology at the Royal Tyrrell Museum.
"The adolescents were agile, so they were able to hunt fast prey the size of an ostrich or a baby turkey," adds Therrien.
Recent research also confirms this. In a study published in 2023 in Science Advances, a team led by Therrien and Zelenitsky analyzed the stomach contents of a young tyrannosaur Gorgosaurus libratus, a close cousin of T. rex, and found the hind limbs of two small dinosaurs, both less than a year old.
"Before this study, we didn't really know what was on the menu for adolescent tyrannosaurs," says Zelenitsky. "This is the first good evidence we have about what juvenile tyrannosaurs ate."
With jaws capable of delivering a bite force of 57,000 newtons, Tyrannosaurus rex was a powerful chewer, pulverizing both bone and flesh. "Adult tyrannosaurs, with their large, broad snouts, were bone crushers," says Therrien.
Nevertheless, fossil evidence suggests that T. rex also ate with precision. In a study published in 2010 in Acta Paleontologica, paleontologists discovered that a Tarbosaurus, another close relative of T. rex, had used its jaws to carefully separate meat from bone while scavenging a hadrosaur carcass.
More recently, in a study published in 2021 in Historical Biology, a team of Japanese paleontologists revealed that Tyrannosaurus rex may even have 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 the T. Rex a cannibal?
It's clear that Tyrannosaurus rex was a ferocious predator. However, like many modern predators, it was both an active hunter and an opportunistic scavenger that wouldn't turn down a free meal if it found carrion.
But the aptly named "King of the Cretaceous" didn't stop at eating individuals of its own species either.
Several studies have found evidence that T. rex practiced cannibalism. In a study published in 2010 in PLOS One, paleontologist Nick Longrich and colleagues analyzed four Tyrannosaurus rex bones - and found deep tooth marks that could only have been made by other T. rex.
Several years later, in a study published in 2015 in The Geological Society of America, the paleontologists documented marks left on a T. rex limb bone that came from a large predator with serrated teeth - again, marking another T. rex as the culprit, 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 not have been the only Cretaceous carnivore to attack its own relatives.
Although the practice has not been extensively documented, paleontologists have found evidence that Majungatholus atopus, a 30-foot-long theropod that roamed the plains of Madagascar 65 million years ago, also ate other members of its own species.
"It's a kind of ultra-cannibalism," says David Burnham. "When you reach a situation where a population of predators is overpopulated, they start killing and eating each other."
Nicholas R. Longrich ,
