Fossil Proves T. Rex Wasn't Just a Scavenger

[Buster's Uncle]

Fossil Proves T. Rex Wasn't Just a Scavenger
Researchers Discover Dinosaur's Tooth in Spine of Giant Plant Eater That Lived Long After the Attack.
By ROBERT LEE HOTZ

A fossil from a failed kill 65 million years ago offers the first direct evidence that Tyrannosaurus rex did indeed hunt its prey, putting to rest recent arguments that the massive dinosaur may have been a scavenger, scientists said Monday.

In the sandstone of South Dakota, researchers discovered the distinctive crown of a Tyrannosaurus tooth, serrated like a steak knife, wedged in the spine of a 4-ton plant-eater called a hadrosaurus that once roamed the American West. The backbone, moreover, had grown over the tooth, indicating the animal had healed and likely lived for years after the encounter, the researchers reported in the Proceedings of the National Academy of Sciences.

"This is smoking-gun evidence that, in fact, Tyrannosaurus did attack animals and did not just go after carrion," said paleontologist Mark Norell at the American Museum of Natural History in New York, who was not involved in the find.

Scientists believe that the Tyrannosaurus rex had a bite stronger than any other known predator—able to tear off up to 500 pounds of flesh in one mouthful—but the broken tooth is a token of the prey that got away.

"The animal was attacked, survived and escaped," said paleontologist David Burnham at the University of Kansas Biodiversity Institute, who helped to analyze the fossil. "Until we found this specimen, people could say that T. rex was a scavenger; here is evidence it attacked living things."

Paleontologist Robert DePalma II at the Palm Beach Museum of Natural History in Florida discovered the telltale tooth stuck in a pair of fused hadrosaur vertebrae during a 2007 field expedition. "It was a very odd bone at first glance," he said. "As soon as I could see that tooth lodged in the side, I knew it was an extremely significant piece."

The researchers examined the embedded tooth using a medical X-ray CT scanner at Lawrence Memorial Hospital in Lawrence, Kan. To identify the species from which it came, they analyzed the fang's distinctive serrations under a microscope. "We were able to conclusively identify the tooth as coming from a Tyrannosaurus rex and no other dinosaur," said Mr. DePalma.

In recent years, some paleontologists had argued that T. rex only fed on the dead. Fossil hunters have previously found dinosaur bones scarred by tooth-marks and skulls punctured by bites, and they have also uncovered trails of fossilized footprints that recorded a predator's pursuit of its prey. Until now, though, they had nothing to identify the specific predators responsible.

"We see puncture marks and gouges from teeth, but the teeth themselves aren't there," said dinosaur expert Thomas Holtz at the University of Maryland. "There was a lack of positive evidence that Tyrannosaurus rex had done it."

Rarely is such evidence of ancient hunting behavior so well preserved, said Mr. Norell. "Here, we are lucky enough to have found a fossil that is a snapshot of things that happened millions of years ago."

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[Buster's Uncle]

Bitten by hungry T. rex, this dinosaur got away
Associated Press
MALCOLM RITTER 19 hours ago

FILE - This Thursday, April 28, 2011 file photo shows a Tyrannosaurus rex dinosaur replica at the Woodland Park Zoo in Seattle. Scientists have unearthed a dramatic remnant of an encounter between a Tyrannosaurus rex and a creature that got away, providing strong new evidence that the famous dinosaur hunted for food. Results were published in the Monday, July 15, 2013, issue of the Proceedings of the National Academy of Science. (AP Photo/Elaine Thompson)

NEW YORK (AP) — The fearsome bite of a hungry Tyrannosaurus rex left behind new evidence that the famous beast hunted for food and wasn't just a scavenger.

Researchers found a part of a T. rex tooth wedged between two tailbones of a duckbill dinosaur unearthed in northwestern South Dakota. The tooth was partially enclosed by regrown bone, indicating the smaller duckbill had escaped from the T. rex and lived for months or years afterward.

Since the duckbill was alive and not just a carcass when it met the T. rex, the fossil provides definitive evidence that T. rex hunted live animals, researchers say in Monday's issue of the Proceedings of the National Academy of Sciences.

The fossil, from around 67 million years ago, indicates the T. rex bit the duckbill from behind and "intended to take it for a meal," said David Burnham of the University of Kansas, an author of the report.

It's not clear whether there was a chase involved, he said.

Experts who didn't participate in the study said there was already ample evidence that T. rex went after live animals as well as scavenging carcasses. It brought a bone-shattering bite and teeth up to a foot long to each task.

The new fossil is the first to include a T. rex tooth embedded in the bones of its prey, giving "extremely strong physical evidence that the attacker was a tyrannosaur," said Thomas Holtz, Jr., of the University of Maryland.

"It's one other bit of evidence (for hunting) fully consistent with the other data already established from lots and lots of lines of evidence," Holtz said.

You might think a T. rex would take down anything in sight, but Jack Horner of Montana State University said it apparently preyed on the weak, the sick and the young instead.

It makes sense that T. rex also scavenged, said Kenneth Carpenter, curator of paleontology at the Utah State University East Prehistoric Museum.

"If there's a free meal, why not?" he asked. But decay can make carcasses toxic after a while, he said, and "at that point, T. rex is going to have no choice but to hunt."

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