Mon, Jan 17, 2011 - Page 7 News List

Small Argentine dinosaur paved way for T-Rex: study


A small predator that hunted in South America 230 million years ago represents one of the earliest-known dinosaurs and foreshadowed later meat-eating beasts like Tyrannosaurus rex, according to scientists from Argentina and the US.

In findings published on Friday in the journal Science, they described the discovery of a dinosaur called Eodromaeus, meaning “dawn runner.” It was a modest creature — measuring about 1.2m long and weighing only 4.5kg to 6.8kg — that walked on two legs and possessed a long neck and tail, sharp claws and saber-shaped teeth.

However, the scientists said it paved the way for some true monsters like T-Rex. Tyrannosaurus, which lived at the very end of the age of dinosaurs 65 million years ago, approached 15m in length and weighed about 6 tonnes.

The scientists found the -fossilized remains of Eodromaeus in Argentina’s “Valley of the Moon,” a region that has provided a glimpse into some of the earliest days of the dinosaurs during the Triassic period.

Eodromaeus was very close to the root of the dinosaur family tree, but already boasted features typical of the later meat-eating dinosaurs.

“It really is the earliest look we have at the long line of meat eaters that would ultimately culminate in Tyrannosaurus rex near the end of the dinosaur era,” University of Chicago paleontologist Paul Sereno, who also took part in the study, said in a statement.

Two near-complete skeletons were found side-by-side in 1996 in a desert area in western Argentina, but scientists had to study the fossils thoroughly to determine that they belonged to a previously unknown dinosaur.

The scientists said Eodromaeus lived alongside another very early dinosaur called Eoraptor, a -similar-sized creature that ate plants whose descendants eventually would include giant, long-necked sauropod dinosaurs like Apatosaurus and the truly gargantuan Argentinosaurus.

Eodromaeus, with its stabbing canine teeth and sharp-clawed grasping hands, was a precursor to the dinosaur meat-eaters called theropods, like T rex, Allosaurus and Giganotosaurus, as well as to birds, the scientists said.

While dinosaurs eventually became the dominant land animals on Earth, these earliest ones were certainly not the masters of their universe. There were many larger reptiles living alongside them that would have easily turned them into a meal.

“We’re looking at a snapshot of early dinosaur life. Their storied evolutionary careers are just unfolding, but at this point they’re actually quite similar,” Sereno said.

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