New study, old find: T. rex was predator

Hollywood movies got it right. Tyrannosaurus rex hunted down and killed its prey, according to new evidence that disproves a long-debated theory that the dinosaur scavenged only from carcasses.

A recent discovery in South Dakota of a T. rex tooth lodged in the spine of a smaller plant-eating dinosaur provides "unambiguous evidence that the T. rex was an active predator," says a report yesterday in Proceedings of the National Academy of Sciences.

"It sends a chill down your spine, that T. rex was the monster in Jurassic Park that would hunt you down and kill you," said David Burnham, a lead researcher from the division of vertebrate paleontology at the University of Kansas.

Some scientists have argued that T. rex, 40 feet long and weighing about 7 tons, was too slow to capture prey and had the physical characteristics of a scavenger of dead animals rather than a hunter of live prey.

Healed wounds on smaller dinosaurs indicate where a predator attacked them. While paleontologists have seen marks that could have come from a T. rex attack, such as punctured bones or tooth marks, there had been no direct link. The new evidence is rare for good reason: prey rarely gets away, according to the report.

In this case, a hadrosaur, a 35-foot-long plant-eating dinosaur, escaped to tell the tale 65 million years later of its attacker through a tooth lodged in its back.

Paleontologist Robert DePalma from the Palm Beach Museum of Natural History in Fort Lauderdale found parts of the hadrosaur skeleton in the Hells Creek Formation of South Dakota. When scientists scanned its fused vertebrae, they discovered a crown tooth embedded in the old wound. An extensive database of dinosaur teeth enabled the team to identify the tooth as belonging to a T. rex.