Was the Tyrannosaurus Rex a Hunter or Scavenger?

Here's How Tyrannosaurus Rex Ordered Its Meals

Tyrannosaurus rex
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Tyrannosaurus Rex has so often been portrayed in Hollywood movies as a swift, merciless, savage hunter — witness that Porta Potty-chomping speed demon of the first Jurassic Park flick—that it's easy to lose sight of the fact that ravenous Rexes are strictly a Hollywood invention, and may or may not bear any connection to the actual truth.

The main reason so many paleontologists — and so many Hollywood moguls — subscribe to the fearsome hunter theory is Tyrannosaurus Rex's teeth, which were large, sharp, and extremely numerous, as well as the enormous size of Tyrannosaurus Rex itself (up to nine or 10 tons for a full-grown adult). It seems unlikely that nature would have evolved such a huge set of choppers for a dinosaur that feasted on already dead (or dying) animals, but then again, evolution doesn't always operate in a strictly linear or logical fashion.

Evidence in Favor of T. Rex as a Scavenger

There are four main strands of evidence in favor of the theory that Tyrannosaurus Rex happened upon, rather than hunted down, its food:

  • Tyrannosaurus Rex had small, weak, beady eyes, where you might expect an active predator to possess super-sharp vision.
  • Tyrannosaurus Rex had famously small, almost vestigial arms, which would have been near-useless in a close grapple with live prey. (However, these arms were only puny in proportion to the rest of T. Rex; in fact, they could bench-press 400 pounds!)
  • Tyrannosaurus Rex was none too fast, more a lumbering lummox than the sleek predator of Jurassic Park. It was once thought that this tyrannosaur could chase down prey at a blistering 40 miles per hour, but today, a relatively pokey 10 mph seems to be a better estimate.
  • Most convincing of all too many scientists, analysis of Tyrannosaurus Rex brain casts shows the presence of unusually large olfactory lobes, which would have been ideal for catching the scent of rotting carcasses from miles away.

T. Rex May Have Been Both a Hunter and a Scavenger

While the Tyrannosaurus Rex-as-scavenger theory has been surprisingly quick to catch on in the scientific community, not everyone is convinced. In the last analysis, this may not be an either/or proposition: like other opportunistic carnivores, T. Rex may have actively hunted at sometimes, and at other times it may have feasted on prey that had either died of natural causes or already been pursued and killed by other, smaller dinosaurs. 

Still not convinced? Consider an analogy from the jungles of Africa: even the most majestic lion, if it's starving, will not turn up its nose at the carcass of a days-old wildebeest, and many extant carnivores have been known to raid the kills of other meat-eaters if they themselves have been unsuccessful in the hunt. In other words, it's not only a dog-eat-dog out in the wild; it's a dog-scavenge-dog world as well!