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|For immediate use||Aug. 16, 1999 No.491|
Geologists at UNC-CH discover states most spectacular fossils
By DAVID WILLIAMSON
UNC-CH News Services
CHAPEL HILL When Brian Coffey, a former University of North Carolina at Chapel Hill student, planned a field trip for an otherwise routine geology honors project in 1995, he had no idea hed help make what his professor called "the most spectacular and important fossil find in North Carolina history."
Casually scraping his pick along the ground at an undisclosed east-central N.C. site to expose fresh rock, he impaled the ankle bone of a prehistoric creature lying just below the surface of an ancient lake or river bed.
"Brian, whos now a graduate student at Virginia Tech, brought the bone to me and asked if it was anything interesting," said Dr. Joseph G. Carter, professor of geology at UNC-CH. "I was very curious because Id never seen anything like it in terms of how the bones joined together. We went back to look more carefully the next day and found and removed a lot more material."
Carter and his students have been working on the remains ever since. Other top paleontologists quickly agreed to join the effort.
"About a year after the initial discovery, we started realizing during the cleaning process that we had something really special," the geologist said. "It was like a series of Christmas presents that just kept getting bigger and bigger."
The late-Triassic Period animal turned out to be a new species and probably a new genus of rauisuchian, a 221-million-year-old reptile that was evolutionarily halfway between dinosaurs and crocodiles, Carter said. Its kind died out just after the first dinosaurs appeared.
"Unlike dinosaurs, which walked on their toes, these guys walked partially upright on their heels and toes like humans do and dominated the world until the dinosaurs took over," he said. "They dominated the early dinosaurs too, but then went extinct, possibly because of climate change and a global catastrophe such as a comet impact. Dinosaurs then got bigger, dominated mammals and went extinct themselves about 65 million years ago."
Because it has not been published yet, Carter cannot disclose the proposed scientific name of the new reptile. He promised, however, that it will be named in honor of Allison Chambers, the late champion of N.C. fossils. The creature -- the major predator on the U.S. East Coast -- was 10 to 11 feet long and weighed between 1,600 and 2,300 pounds. It resembled a Jurassic allosaurus.
"This guy was built something like a football player with a thick neck, powerful shoulders and long arms," the geologist said. "Unique for rauisuchians, it also had a thumb hooked into the base of his second finger to make a powerful pincer-like grip. When you put those together, youve got a really super predator."
The professor and his students also found "a whole suite of bones" where the reptiles stomach would have been, Carter said. Included was another new mammal-like reptile, which Drs. Hans-Dieter Sues of the Royal Ontario Museum, Dr. Paul Olsen of Columbia University and Carter have named Plinthogomphodon herpetairus.
Also in the stomach were armor plates from a 2- to 3-foot long creature called Aetosarus that had a pointed nose and tail and looked like "a little streamlined armadillo."
Beneath the larger animal were the remains of still another crocodile-like reptile known as a sphenosuchian. That creature, now being studied in Canada, walked on long, spindly legs like a dogs.
"We found it beneath the rauisuchians left leg like it had been pinned down," Carter said. "We arent sure what the relationship between the two was. It may be that they died together, or they may have been washed together."
The "superb" specimen is the most complete sphenosuchian from the late Triassic Period ever found, he said.
Unfortunately, Carter said, his team was able to recover only about 5 percent of the rauisuchians skull. Thats because a bulldozer operator scraped the area, also destroying part of the hip and tail before Coffey found the first bones.
Previously, the most famous North American rauisuchian, Postosuchus, was found near Lubbock, Texas. Saurosuchus, a close relative found in Argentina, was roughly twice as long as the Tar Heel reptile and weighed far more.
Growth banding in the new species bones showed it to be relatively young when it died, between 10 and 13 years. It appears to have had some form of systemic infection.
"We have evidence of abscesses in many of its bones and that something left fresh-looking tooth marks on its arms that had never healed," the geologist said. "It may have died because it was being attacked in or near the lake, or it was wounded just before it died. The body probably got washed into the lake or river and was then buried very quickly."
Among the 10 or so former and current UNC-CH students who have worked hard on the project, were Swiss native and masters candidate Karin Peyer, brothers David and Matthew Campbell and Margaret Moncure, he said. For nearly a year, Samantha Harlowe worked on a badly shattered arm that was a critical piece of the puzzle, he said. A freshman seminar will be held this fall using the fossils as the focus for a study group on dinosaurs and other reptile evolution.
"The Triangle Brick Company owns the land, and we are very grateful to company officials for their cooperation," Carter said. "We need to emphasize that there is nothing of this thing left at the site. We know that because we looked very carefully.
"This discovery, the first substantial find of a rauisuchian on the East Coast of North America, was in a way a remarkable fluke," he said. "Ive been going to these areas for 23 years, and the most Ive found are little bits and pieces of bones. Other faculty here have been going to the same counties for 30 or 40 years, and its been the same with them."
Note: Carter can be reached at (919) 962-0685. For a photo, call campus photographer Dan Sears at 962-8592.
Contact: David Williamson, (919) 962-8596. E-mail: David_Williamson@unc.edu or Dennis Baker, 962-0352.