Bones may reveal new eating behavior for T. rex

Dusting off scraps of hadrosaur bones from a museum collection, a UW undergraduate has found evidence for a previously unrecognized feeding behavior for Tyrannosaurus rex.

In a presentation here today (Nov. 9) at a meeting of the Geological Society of America, Daniel Hyslop, a senior, offered evidence that the mighty T. rex, the unchallenged king of the Cretaceous carnosaurs, may have scraped the meat off the ribs of its prey in much the same fashion a human might glean a meal from baby back ribs.

“The bite marks are very unusual,” says Hyslop who found the chewed-on bone scraps in the collections of the Geology Museum. “And they give us a few more hints about the mechanics of how this animal ate.”

For all its notoriety, T. rex and its behaviors are known from only a handful of complete skeletons and other fossil evidence. Superbly equipped as a predator with a mouth full of curving, dagger-like teeth, paleontologists suspect that T. rex was both a predator and a scavenger, taking advantage of any easy meal it came across.

The bite marks identified by Hyslop in no way resolve the argument over whether the animal was strictly a predator, opportunistic scavenger or both, but they do add to the fossil record a previously unknown behavior. They suggest that the most fearsome animal of its time may have gnawed and worried bones, in dog-like fashion, to obtain a tasty meal.

“This is just one of a very few pieces of evidence about T. rex feeding behavior,” says Hyslop, who has been an active volunteer for several years at the Geology Museum. “The literature mostly shows big punch holes” where the sharp, conical teeth of the dinosaur left impressions in bone that, in some cases, yielded near-perfect casts of T. rex teeth when filled with plastic. Evidence that T. rex may have, with some dexterity, scraped meat off the bones of the animals it consumed has never before been presented.

The tooth marks found by Hyslop on a few small scraps of bone, have proved to be a near-perfect match to the tooth of a Tyrannosaurus. Curving concentrically along the rib, the marks exhibit a series of small grooves, like neat furrows in a farm field, that fit the serrated edge of a T. rex tooth.

“Just from how uniformly spaced the marks are, you can tell they were not a result of weather or water. It pretty much has to be T. rex. The size is right on,” Hyslop explains, noting that the marks did not match the dentition of other known predators and scavengers.

Hadrosaurs, known more commonly as duck-billed dinosaurs, were contemporaries of T. rex and roamed in great herds across what is now the American West, where the rib fragments were found. Like the horned Triceratops, hadrosaurs were almost certainly on the menu for what was unquestionably the top predator in that environment 65 million years ago.

The new-found bite marks, Hyslop notes, are just small clues, found on otherwise inconspicuous fossils, that may help fill in the void of knowledge about how one of the Cretaceous world’s most fearsome animals behaved.