It looks like the most badass predator to have ever roamed the Earth, but paleontologists have struggled to prove that Tyrannosaurus rex actually hunted its prey, leading some to believe that it was a scavenger. Now, the discovery of a T-rex tooth embedded in the tail of a hadrosaur offers the first direct evidence.
Top image: Robert DePalma depicts the possible attack scenario between a T-rex and hadrosaur.
That T-rex may have been a scavenger isn’t as crazy a theory as it might appear; this is actually a longstanding debate that goes back nearly a century.
Paleontologists have uncovered tons of bones with tooth drag and puncture marks that would indicate predatory attacks, but these markings are difficult to attribute to a specific theropod. What’s more, some of these tooth marks could have been made on carcasses.
Yet other theories have speculated that there were too many Tyrannosauruses for the species to survive on hunting alone; it was more like a hyena than a cheetah or a lion, having to rely on opportunistic feeding to sate their appetites given their relative abundance.
Two Fused Vertebrae and a Tooth
But owing to a discovery made at a site in South Dakota by paleontologist David Burnham and his graduate student Robert DePalma, we now know that T-rex did indeed hunt its prey.
The scientists found a Tyrannosaurus rex tooth lodged in the tail vertebrae of a plant-eating hadrosaur (sometimes referred to as the “duck-billed dinosaur”). Moreover, their analysis of the fossil showed that there was fresh bone growth surrounding the tooth, an indication that the hadrosaur survived the attack.
Based on their analysis, the encounter likely happened in the Late Cretaceous about 66 million years ago. After the attack, bone grew over the wound, fusing the two vertebrae together. This healing process would have likely taken several years, so the herbivore lived long after the close call.
Image: CT scans showing cross-sections of the vertebrae. The teardrop-shaped object at bottom is the tooth, with bone growth enveloping it. Credit: PNAS/Burnham et al.
But not everyone is excited — or convinced — by this finding. In fact, paleontologist John Hutchinson says this is a non-issue as far as the science is concerned, and that this is more media hype than anything else. The whole “predator vs. scavenger” debate, he says, has distracted the public from more important controversies in paleontology.
Here’s his unedited response to Matt Kaplan of Nature News:
I find this very unfortunate. It is not like scientists sit around scratching their heads in befuddlement over the question, or debate it endlessly in scientific meetings. Virtually any palaeontologist who knows about the biology of extant meat-eaters and the fossil evidence of Late Cretaceous dinosaurs accepts that T. rex was both a predator and scavenger; it was a carnivore like virtually any other kind that has ever been known to exist.
While the discovery is nice evidence, it is not particularly exciting in a scientific sense and is only one isolated element from species that lived for hundreds of thousands of years, which to me changes nothing and allows no generalizations about the biology of any species, only the statement that at one point in time a Tyrannosaurus bit a hadrosaur that survived the encounter. There is no real substance to the controversy that T. rex was “either” a predator or scavenger. It is just something that scientists drum up now and then to get media attention. I hope that soon we can move on to more pressing questions about the biology of extinct animals, but the media needs to recognize that this is just hype and they are being played in a rather foolish way; likewise scientists that still feel this is an exciting question need to move on. Maybe this specimen will allow that. But somehow my cynical side leads me to suspect that this “controversy” will just persist because people want it to, regardless of logic or evidence.
Great galloping lizards, I am so tired of this nonsense. Maybe there is educational value in showing how science deals with provocative half-baked ideas about celebrity species, but scientists in the community need to speak up and say what the real science is about. It’s not about this “controversy”. Modern palaeontology is so much better than this.
Two things I’ll say about Hutchinson's rant.
First, I totally buy the argument that T-rex was probably both a predator and an opportunistic feeder. Why not? A monster like that could pretty much do as it pleases, both as a hunter and as a creature that fed on any scraps it could find, quickly dispatching any other animal who would dare encroach on its easy meal.
Second, Burnham and DePalma’s discovery is cool — no two ways about it. The fact of the matter is that it’s truly the first direct physical evidence of T-rex’s predatory inclinations. And regardless of the ensuing “media hype,” it’s still science — and it’s still important.
Read the entire study at PNAS: “Physical evidence of predatory behavior in Tyrannosaurus rex.”