Fossils Reveal a Rival to T. Rex
MOVE over, Tyrannosaurus rex. Newfound fossils reveal a beast that may be the biggest meat-eating dinosaur known, scientists reported in the current issue of the journal Nature.
Scientists estimate that the dinosaur, which resembled T. rex, was 41 to 43 feet long and weighed 6 to 8 tons when it roamed the plains in what is now Argentina looking for food to chomp with its huge serrated teeth.
It lived about 100 million years ago, which is about 30 million years before T. rex appeared, said Dr. Rodolfo Coria, one of the authors of the report and a paleontologist at the Carmen Funes Museum in Neuquen, Argentina. A bone-by-bone comparison with the remains of the largest known specimen of T. rex suggests that the newly discovered creature was slightly longer and maybe 3 tons heavier, Dr. Coria said.
The fossils were discovered by an automobile mechanic who hunts for dinosaur bones as a hobby, Dr. Coria said. In honor of the discoverer, Ruben Carolini, the huge dinosaur has been named Giganotosaurus carolinii.
Scientists have recovered about 70 percent of the skeleton. Without a complete skeleton scientists can only estimate the creature's size, Dr. Coria said. The dinosaur ran on its hind legs and probably had rather small arms, he said in a telephone interview. Exactly what it ate in its environment, which resembled the African savanna, is a mystery.
Despite the overall similarity to T. rex, Giganotosaurus was not closely related to it, and the two beasts arose independently in two places, isolated by time in space, where there were ecological niches for gigantic meat-eating dinosaurs, said.
T. rex lived in North America, and there was no land bridge from South America that could have let Giganotosaurus or its descendants move north to become ancestors of T. rex, Dr. Sereno said.
Jack Horner, curator of paleontology at the Museum of the Rockies in Bozeman, Mont., said that comparing the sizes of Giganotosaurus and T. rex is tricky because dinosaurs grew continuously until they died. As a result, scientists have no firm answer on how big T. rex got. Estimates range from about 40 feet to 50 feet.
Fossils of a meat-eating dinosaur from North Africa suggest another beast that may have been bigger than T. rex, Mr. Horner said. But no analysis of those bones has been published.
More important than determining its size will be finding out whether Giganotosaurus was a hunter or a scavenger, Mr. Horner said.