A Meat Eater Bigger Than T. Rex Is Unearthed
A new dinosaur species, one of the largest known carnivorous dinosaurs, has emerged from the red sandstone of Patagonia, in Argentina, where reptilian giants seem to have thrived 100 million years ago.
Paleontologists reported yesterday that they had found the fossils of seven to nine individuals of a species they are naming Mapusaurus roseae.
An analysis of the bones showed that an adult exceeded 40 feet in length, which the discoverers said was slightly larger than specimens of both its close relative, Giganotosaurus, and Tyrannosaurus rex. Some scientists think that a Spinosaurus species from North Africa is the largest meat-eating dinosaur, but that is still debated.
The discovery was made in sediments of a 100-million-year-old water channel at a site 15 miles south of Plaza Huincul, Argentina. It was reported at a news conference in Plaza Huincul and described in the French journal Geodiversitas.
Rodolfo A. Coria of the Carmen Funes Museum in Plaza Huincul and Philip J. Currie of the University of Alberta in Edmonton, co-leaders of the excavations, said they found hundreds of Mapusaurus bones in the sediments. Nearly all of the bones were scattered, and not in their original skeletal arrangements.
The skull is lighter than that of Giganotosaurus, but with the sharp, blade-shaped teeth that are the trademark of predatory dinosaurs. One of the most intriguing bones, the paleontologists said, was the longest known fibula, or shin bone, for any meat-eating dinosaur.
The fossils were excavated over five years, beginning in 1995, before scientists realized they were dealing with a new species of giant carnivores, members of the broader meat-eating carcharodontosaurids, Dr. Currie said.
'Preparation later revealed that skeletal parts represented more than a single individual,' the two scientists wrote in the journal. They estimated that the dinosaurs ranged in size from slender juveniles 18 feet long to a robust adult of at least 40 feet long.
The scientists said Mapusaurus apparently lived at the same time and place as the largest known dinosaur, the 125-foot-long Argentinosaurus plant eater that Mapusaurus presumably hunted. The genus name Mapusaurus is derived from the word for earth among the Mapuches, the native people of western Patagonia.
The discovery, along with other recent ones in Canada, Mongolia and the United States, appeared to support an emerging interpretation of the hunting behavior of predatory dinosaurs. Instead of being solitary hunters, as once thought, they may have operated in groups.
'The presence of so many animals in one quarry,' Dr. Currie said in a statement released by the University of Alberta, 'suggests that they were living together in a pack at the time leading up to their catastrophic death.'
Correction:  May 1, 2006, Monday  An article in Science Times on April 18 about the discovery of a species of dinosaur in Argentina included an incorrect reference to a fossilized bone described by paleontologists as the longest known fibula for any meat-eating dinosaur. The fibula is the calf bone, not the shinbone.