July 30, 2008
New Research Has a Bone to Pick About Dinosaur Soft Tissue
By Dan Vergano
New research is challenging claims made three years ago that scientists had discovered soft tissue remnants in the thighbone of a Tyrannosaurus fossil.
Finding tissue preserved at least 65 million years shocked paleontologists who believed any such traces were lost forever.
Last year, the team reported a close link between birds and proteins from dinosaur fossils, as well as between birds and mammoth tissues. Birds and dinosaurs are related.
But a team led by Tom Kaye of the Burke Museum of Natural History in Seattle suggests that the researchers in 2005 mistook modern-day bacterial goo -- more properly called biofilm -- for dinosaur remnants.
Using high-tech microscopes, Kaye's team looked at the interiors of fossils from 17 dinosaur species discovered near the Tyrannosaurus fossil to check the finding about blood vessels.
If the material reported in the Science study had been soft tissue, it would have somewhat resembled modern-day collagen, the connective tissue in skin and blood vessels.
Instead, the coatings bear closer molecular resemblance to modern biofilms than to collagen, the team reported Tuesday in the journal PloS One.
But Schweitzer disagrees. "The idea that biofilms are completely and solely responsible for the origin or source of the structures we reported is not supported," she said by e-mail from a dinosaur dig in Montana.
Microscopic views of bones can't explain why the fossil tissues reacted to the immune cells of chickens, for example, and the mammoth ones reacted with elephant cells, she says.
"Although this revelation may seem like a major setback, we shouldn't lose heart," says paleobiologist David Martill of the United Kingdom's University of Portsmouth, who was not part of either study. "But we will have to be much more careful with our analyses."
Says Kaye: "If they had just reported proteins from one Tyrannosaurus rex, we could say they were fortunate in that one, but if they are finding them elsewhere, we should be seeing them all over. And we aren't."
However, Kaye acknowledges that his study does not refute the immune responses reported by Schweitzer's team. "They have single-handedly pioneered the use of sophisticated chemical analysis and have created a critical bridge between biology and paleontology," he says.
More analyses of the suspect tissues are underway, Schweitzer says. "I guess the best I can say is: Stay tuned!" (c) Copyright 2008 USA TODAY, a division of Gannett Co. Inc. <>>