What did T. rex eat? Each other

Oct 15, 2010
T. rex was the only big carnivore in western North America 65 million years ago that was capable of making such large gouges, such as the ones seen here on a toe bone. Credit: Nicholas Longrich/Yale University

It turns out that the undisputed king of the dinosaurs, Tyrannosaurus rex, didn't just eat other dinosaurs but also each other. Paleontologists from the United States and Canada have found bite marks on the giants' bones that were made by other T. rex, according to a new study published online Oct. 15 in the journal PLoS ONE.

While searching through dinosaur fossil collections for another study on dinosaur bones with mammal tooth marks, Yale researcher Nick Longrich discovered a with especially large gouges in them. Given the age and location of the fossil, the marks had to be made by T. rex, Longrich said. "They're the kind of marks that any big carnivore could have made, but T. rex was the only big carnivore in western North America 65 million years ago."

It was only after discovering the bite marks were from a T. rex that Longrich realized the bone itself also belonged to the behemoth. After searching through a few dozen T. rex bones from several different museum fossil collections, he discovered a total of three foot bones (including two toes) and one arm bone that showed evidence of T. rex cannibalism, representing a significant percentage.

"It's surprising how frequent it appears to have been," Longrich said. "We're not exactly sure what that means."

The marks are definitely the result of feeding, although scientists aren't sure whether they are the result of scavengers or the end result of fighting, Longrich said, adding that if two T. rex fought to the death, the victor might have made a meal out of his adversary. "Modern big carnivores do this all the time," he said. "It's a convenient way to take out the competition and get a bit of food at the same time."

However, the marks appear to have been made some time after death, Longrich said, meaning that if one dinosaur killed another, it might have eaten most of the meat off the more accessible parts of the carcass before returning to pick at the smaller foot and arm bones.

While only one other dinosaur species, Majungatholus, is known to have been a cannibal, Longrich said the practice was likely more common than we think and that closer examination of bones could turn up more evidence that other species also preyed on one another.

The finding is a big clue into the obscure eating habits of these enormous predators. While today's large carnivores often hunt together in packs, T. rex likely acted on their own, Longrich said. "These animals were some of the largest terrestrial carnivores of all time, and the way they approached eating was fundamentally different from modern species," he said. "There's a big mystery around what and how they ate, and this research helps to uncover one piece of the puzzle."

Explore further: Paleolithic diet may have included snails 10,000 years earlier than previously thought

More information: Citation: dx.plos.org/10.1371/journal.pone.0013419

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User comments : 10

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Shootist
1 / 5 (1) Oct 16, 2010
What did T. rex eat?


I suspect the real answer is, "anything that want".
LuckyBrandon
4.2 / 5 (5) Oct 16, 2010
how are the bites for sure from feeding? Seems to me its just as likely that they were fighting...maybe mating season? that would explain a high frequency of tooth marks too...
StillWind
2 / 5 (4) Oct 16, 2010
I'd be interested in the evidence that these were made post mortem.
I'm also interested in what evidence we have of behaviour.
I realize that we can surmise all kinds of scenarios, but we have no real evidence of any kind of behaviour.
This is not science.
ultrasnow
not rated yet Oct 16, 2010
Maybe love bites ?
gmurphy
not rated yet Oct 16, 2010
T-Rex eroticism gone too far, hehe :-D
Valentiinro
1 / 5 (1) Oct 16, 2010
Maybe love bites ?

Love bites on bone? Sounds like they were doing it wrong!
LuckyBrandon
1 / 5 (1) Oct 16, 2010
no no im thinking fighting for their mates...
bhiestand
not rated yet Oct 17, 2010
I'd be interested in the evidence that these were made post mortem...This is not science.

Who are you to determine that this is not science? I assume you're a scientist, have read the actual article, and are willing to put your professional reputation on the line to back that assertion.

This isn't even remotely related to my field and I can tell you it's not that difficult to distinguish between feeding traces (marks left by gnawing, picking the meat off the bones, etc.) and normal injuries.

I imagine post-mortem is also fairly simple to determine since we've had that capability in forensic criminal investigations for quite some time. Just looking at some of those pictures, I can tell you it's quite unlikely they were made to an animal that was conscious and able to defend itself... these aren't little bites.

Of course, if you're so "interested", you could just read the full text article directly linked after the words "More information:"
bhiestand
not rated yet Oct 17, 2010
To pull a few quotes from the article and answer a few questions:

We argue that these traces result from feeding, rather than intraspecific combat. First, these traces would have been difficult to inflict on a live animal. In the case of MOR 1126, bite marks occur on both the proximal and distal ends of the bone and the shaft, suggesting that the bone was bitten two or three times. It seems unlikely that a small Tyrannosaurus would be allowed to repeatedly bite a much larger individual several times on a single toe.


...the absence of healing in any of these specimens is also consistent with the hypothesis that the tooth marks were made on carcasses.
Quantum_Conundrum
3 / 5 (2) Oct 18, 2010
Even if one T-Rex ate another, it doesn't prove all of them were cannibalistic. Some human groups have been cannibalistic in the past, does that mean all humans are cannibals? Of course not.

Maybe food was scarce or something.

Maybe, as already pointed out, the creatures were fighting over a mate.

Predatory animals often have self-destructive reproductive behavior.

Male cats of all sizes have been known to kill their own young, presumably so they can mate with the female again.