Newswise — A Tyrannosaurus rex discovered during a lunch break in eastern Montana -- and the oldest T. rex on record -- has produced the latest major discovery in dinosaur paleontology, said Jack Horner, curator of paleontology at Montana State University's Museum of the Rockies. Researchers led by Mary Higby Schweitzer, formerly of MSU, found soft tissues preserved in both hind thigh bones of the dinosaur, according to an article in the March 25 issue of the journal Science.

The dinosaur known as B. rex also contained transparent, flexible and hollow blood vessels with round microscopic structures inside. The structures look like cells, leading the scientists to believe that some dinosaur soft tissues may keep a portion of their flexibility, elasticity and resilience even after 68 million years.

B. rex, found north of Jordan, Mont. in 2000, is estimated to be about 68 million years old. "I am quite aware that according to conventional wisdom and models of fossilization, these structures aren't supposed to be there, but there they are," said Schweitzer, lead author of the paper. "I was pretty shocked." She wouldn't believe the outcome until her technician repeated the experiments about eight times, said Schweitzer, assistant professor in the Department of Marine, Earth and Atmospheric Sciences at North Carolina State University in Raleigh and former doctoral student of Horner's. Horner, listed as third author of the paper, said, "I see this as a really important discovery that will change our methods of collecting and study. We can truly begin asking biomolecular questions. The discovery also means that our preconceived ideas about preservation were wrong." When dinosaur nests and babies were discovered at Egg Mountain near Choteau, Mont., scientists started looking at dinosaur parenting. Learning how dinosaurs might have behaved became a part of dinosaur paleontology. "Now, with these new discoveries of cellular preservation, we move to a new kind of paleontology: cellular and molecular paleontology," Horner said. Horner and a spokeswoman for Science predicted the paper would stir controversy. "It will be controversial because of those preconceived ideas about what can and cannot be preserved over long periods of time," Horner said. "It has always been thought that cells couldn't be preserved, but there really wasn't any evidence to back up those ideas, other than no one having found cellular preservation before."

B. rex was one of 31 dinosaurs found over four years in the Hell Creek Formation around Jordan and the Fort Peck Reservoir in Montana. All located on U.S. Fish and Wildlife Service property, they were discovered during a major effort to reconstruct the dinosaur-dominant ecosystem that existed there 65 million years ago. Bob Harmon, chief preparator of paleontology at the Museum of the Rockies, found B. rex after hiking into a steep box canyon. "I was out looking for dinosaurs and actually stopped to eat lunch along side a big 50-foot cliff and just turned around and looked behind, and one of the foot bones of a T. rex was sticking out of a cliff," Harmon said. "I went up and looked and could see some other bones sticking out." MSU crews went on to spend three summers, using jackhammers and rock-climbing harnesses, removing 46 feet of rocks and sediments above the dinosaur. Some bones were slightly deformed or crushed, but preservation overall was excellent, according to Science. "It's a beauty," Harmon said of the dinosaur named after him. To study its soft tissue vessels and cellular preservation, Schweitzer removed minerals from the bone and conducted chemical analyses. She dehyrdrated and rehydrated bone tissue. She stretched and restretched blood tissue. She used scanning electron microscopy to compare features of the dinosaur vessels with those found in ostriches. Ostriches are primitive birds known to be related to dinosaurs. She isolated transparent vessels from two other exceptionally well-preserved T. rexes and compared those to the B. rex.

An explanation for B. rex's condition is part of her ongoing research, Schweitzer said. Horner said he didn't think it was preserved any better than any other T. rex in sandstone.

"It's simply the first dinosaur that has been studied in this manner, and therefore the first dinosaur to have yielded this kind of information," Horner said. "I'm sure that many other dinosaurs are going to preserve the same material when people begin looking." Science is a weekly journal that publishes scientific news, as well as the most significant breakthroughs in global research. It is the world's largest circulation journal for a general science audience.

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Science, March 25, 2005 (25-Mar-2005)