Path: bloom-picayune.mit.edu!snorkelwacker.mit.edu!americast.com!americast.com!americast-post Newsgroups: americast.twt.news From: americast-post@AmeriCast.Com Organization: American Cybercasting Approved: americast-post@AmeriCast.com Subject: Grandmother of all dinosaurs pieced together by scientists Date: Fri, 13 Nov 92 15:11:15 EST Message-ID: \SE A;NATION \SS (WS) \HD Grandmother of all dinosaurs pieced together by scientists \BY ASSOCIATED PRESS Researchers have assembled an almost-complete skeleton of a 400-pound reptile that ran on its hind legs, ripped prey apart with jaws and claws, and probably was the ancestor of Tyrannosaurus rex, the largest meat-eater to walk the Earth. University of Chicago paleontologist Paul Sereno said skeleton parts pieced together from a fossil find in Argentina show that a 230-million-year-old carnivore called Herrerasaurus is the earliest know meat-eater in the dinosaur family. "This represents the most primitive early phase of the carnivorous line of dinosaurs," Mr. Sereno said. In a study to be published today in the journal Science, Mr. Sereno said that characteristics of the Herrerasaurus show that the evolution of dinosaurs into specialized hunters and plant-eaters began very early in the 180-million-year dinosaur reign. "We see in these deposits that dinosaurs had already split into a couple of groups," he said. "Dinosaurs had already done a little branching already, even though they did not then dominate numerically. . . . This is a bit unexpected." The Herrerasaurus was first identified 30 years ago, said Mr. Sereno, but the proposed appearance of the animal was based on leg and pelvis bones. In 1988, he said, University of Chicago researchers found almost-complete skeletons of the animal in a valley in the Argentine foothills of the Andes Mountains. Mr. Sereno said the deposit was rich with fossilized remains and the researchers were able to put together the most complete skeleton of Herrerasaurus ever found. "We came up with five skeletons and though none of them are complete down to the last bone, it becomes very apparent after overlapping these things what kind of animal you have," he said. "It tells us what the dinosaurs looked like in this early phase." Distinctive features found in the completed skeleton showed that the animal had already developed adaptations that later would be found in Tyrannosaurus rex, the 40-foot hunter that ruled the final era of the dinosaur age. Herrerasaurus lived about 230 million years ago, near the very beginning of the dinosaur age, and Tyrannosaurus rex first appeared about 70 million years ago. Dinosaurs became extinct about 65 million years ago. Mr. Sereno said adult Herrerasaurus dinosaurs were 10 to 20 feet long and weighed 300 to 450 pounds. The animal had long, powerful hind legs and short forearms that ended in a hand with three dominant fingers. "Its hand is very large with recurved claws," said the Chicago researcher. "It is very well adapted for grasping and for raking flesh off of animals." The skull is dominated by a large mouth fitted with inward-curving teeth and a jaw designed for a hunter. "It has a flexible lower jaw that can bend around and hold a prey. It is for subduing something that is struggling," said Mr. Sereno. "That is an adaptation that is seen in the later carnivorous dinosaurs." This article is copyright 1992 The Washington Times. Redistribution to other sites is not permitted except by arrangement with American Cybercasting Corporation. For more information, send-email to usa@AmeriCast.COM