In recent years there has been considerable debate within the scientific community about the lifestyle of the infamous dinosaur species the Tyrannosaurus rex — the two main camps have argued either for the idea that the T-Rex was an active apex predator that hunted, or for the idea that it was primarily a ‘bully’ scavenger that would search out kills made by other animals and then take over the kill. Obviously though both behaviors could have been exhibited by the species, or perhaps varied strategies based on age/size, environment, other factories, etc
New evidence though — a fossilized T-Rex tooth discovered embedded in a fossilized hadrosaur spine — is suggesting though that at the very least, the animal’s did occasionally hunt large prey, if not mor often.
“T. rex is the monster of our dreams,” stated David Burnham, preparator of vertebrate paleontology at the Biodiversity Institute at the University of Kansas. “But ever since it was discovered in Montana and named in the early 1900s, there’s been a debate about whether these large carnivores were scavengers or predators. Most people assume they were predators, but the scientific evidence for predation has been really elusive. Yes, we’ve found lots of dinosaur skeletons with tooth marks that had been chewed up by something. But what did that really prove? Yes, these large carnivores fed on other dinosaurs — but did they eat them while they were alive or dead? That’s where the debate came in. Where was the evidence for hunt and kill?”
The new fossil discovery is now providing some evidence though — in the Hell Creek Formation of South Dakota, the researchers “discovered the crown of a T. rex tooth lodged in the fossilized spine of a plant-eating hadrosaur that seems to have survived the attack.”
“Robert DePalma was a student here at KU doing his master’s thesis in the Hell Creek formation,” said Burnham. “He found a specimen that represents the tail of one of these hadrosaurs. It had a distorted-looking bone growth. He came to me and said, ‘What do you think is causing this?’ So we cleaned it and could see a tooth embedded in one of these duck-billed dinosaur vertebrae. Then we went to Lawrence Memorial Hospital and used a CT machine to scan the bones — and we saw all of the tooth.”
While this is good evidence, it isn’t the entirely the first — previous evidence includes finding T. rex fossils with preserved stomach contents that included the bones of a young ceratopsian (e.g., Triceratops or one of its kin). What wasn’t lear before though was whether or not the ceratopsian was killed by the T. rex or not.
The new fossil tooth though is a different story. “Lo and behold, the tooth plotted out just exactly with T. rex — the only known large theropod from the Hell Creek formation,” he said. “We knew we had a T. rex tooth in the tail of a hadrosaur. Better yet, we knew the hadrosaur got away because the bone had begun to heal. Quite possibly it was being pursued by the T. rex when it was bitten. It was going in the right direction — away. The hadrosaur escaped by some stroke of luck. The better luck is finding this fossil with the preserved evidence.”
“Because T. rex regularly shed its teeth, the predator went away hungry, but otherwise no worse for the encounter. It would have grown a new tooth to replace the one left behind in the hadrosaur’s tail. This could have been a typical example of T. rex’s hunting efforts, even if it didn’t result in a meal.”
“To make an analogy to modern animals, when lions go attack a herd of herbivores, they go after the sick and the slow,” Burnham stated. “Most of the time, hadrosaurs traveled in packs. This hadrosaur may have been a little slower, or this T. rex may have been a little faster — at least fast enough to almost catch a duck-billed dinosaur.”
The new research was just published in the most recent issue of the Proceedings of the National Academy of Sciences.