Largest meat-eating dinosaur discovered
Philip Currie views the dinosaur's razor-sharp teeth
Scientists have discovered the bones of what may be largest meat-eating dinosaur ever to walk the Earth - a razor-toothed beast more terrifying than the Tyrannosaurus rex.
This guy has a long snout and incredibly sharp teeth - I think it would have been terrifying
Philip Currie A team of palaeontologists from Argentina and North America unearthed the fossils in the Patagonian desert, on the eastern slopes of the Argentinian Andes. There may be as many as six creatures preserved at the site.
The predators' graveyard challenges the theory that the biggest meat-eaters were always loners. It suggests that these killers lived in packs, making them even more menacing to their prey.
Dissecting prey
"You always think of these things as being solitary. Now we know they travelled in packs," said Philip Currie, one of the team at the Royal Tyrrell Museum in Alberta, Canada.
Dr Currie said the newly-discovered species lived about 100 million years ago and was heavier, with slightly shorter legs, than the T-rex.
The dig which unearthed the dinosaur bones began in 1997
The dinosaur also had a long, narrow skull and a jaw shaped like scissors. That suggests it could have dissected its prey with almost surgical precision, Dr Currie added.
Researchers estimated the meat-eating giant was 13.7 metres (45 feet) long, bigger than the reigning king of the carnivores, the 12.5 m (41 ft) Giganotosaurus. The better-known T-rex was about 12.2 m (40 ft) long.
"I think it would look just as nasty, if not worse," Dr Currie said. "This guy has a long snout, long skull, incredibly sharp teeth - I think it would have been terrifying."
As big as it gets
Dr Currie believes the animal is related to the Giganotosaurus, but is a new species and genus, making the two creatures as closely related as a dog and a fox. The dinosaur is further removed from the T-rex, at least as different as a dog is from a cat.
"The bigness of it gets headlines but, scientifically, it's not that important. But the fact that they travelled together, that's very interesting," said Jack Horner, a palaeontologist from Montana State University.
Thomas Holtz, a palaeontologist at the University of Maryland, said future researchers are not likely to come upon carnivorous dinosaurs much larger than Dr Currie's find.
"I think we're getting close to the size limit you could be and still be an effective meat-eater," said Dr Holtz. "If you get too large, you won't be able to hunt down prey because you'll simply be too ponderous."