July 31, 2008
T. Rex Tissue Discovery Questioned
By Zoe Elizabeth Buck, The News & Observer, Raleigh, N.C.
Jul. 31--A fossil researcher at a Washington state museum has triggered doubts about the discovery of Tyrannosaurus rex tissue by N.C. State paleontologist Mary Schweitzer.Three years ago, Schweitzer's team gained international headlines with the news they had uncovered the thigh bone of a 70 million-year-old dinosaur in Montana with what appeared to be blood vessels and maybe even whole cells embedded inside. The discovery shook the world of dinosaur paleontology. Until then, the only thing scientists had to understand the ancient giants were fossilized bones.
Now Schweitzer's findings are being challenged as little more than pond scum.
Thomas Kaye, a research associate at the Burke Museum of Natural History in Seattle, published a study online Tuesday in the journal PLoS ONE, published by the Public Library of Science. The paper, co-authored by researchers at Jagiellonian University in Poland and Microtechnics Inc., a California microscope company, suggests that Schweitzer's team mistook biofilm -- a type of modern bacterial goo -- for ancient dinosaur tissue.
"If you've ever left a bucket of water out in the backyard for a week and you feel the inside and it feels slimy, it's the same stuff," explained Kaye.
He suggests that the spaces where blood vessels once were act as channels inside dinosaur bones. When water gets into the bones, Kaye said, it coats the inside of these holes with slime, and then the slime dries in the shape of the vessels. He contends that's why, when Schweitzer's team melted away the bones, it looked as though there was soft tissue preserved inside.
Kaye's paper drew immediate attention in the science media and other publications. But Schweitzer remained unconvinced, and a little perturbed.
"While we welcome the skepticism of colleagues, we hope that the reviewers and readers hold them to the standards to which we are held," Schweitzer said in a lengthy e-mail response she sent from an excavation in Montana. "Science progresses by scrutiny and testing."
Schweitzer said Kaye's analysis doesn't hold up on many levels.
"Looking at all data together," she wrote, "the idea that biofilms are completely and solely responsible for the origin or source of the structures we reported is not supported."
Kaye says there are more questions to be asked about biofilm.
"It's like when you're investigating a crime scene," he said, "and one team takes specimens back to the lab, and another team looks at the body and the blood spatters. Their chemical results say one thing, our blood splatters say something else."
Kaye, an inventor who built a paintball equipment company while pursuing paleontology and astronomy as hobbies, said that his paleontological credentials are thin. But he has led expeditions to collect fossils for exhibits at the Burke Museum, and published scientific papers.
"I have no education that relates to this," he said. "I got involved in the early '90s when I was working with graduate students."
Kaye said he stumbled on his results in an effort to reproduce what Schweitzer found.
"I happen to like Mary Schweitzer, and I love her work, and I got very excited about it," he said. "I set out trying to find soft tissue, too."
The findings drew some level of skepticism from other scientists.
Rich Thompson teaches a class about dinosaurs at the University of Arizona, although his background is in crystallography. Thompson has met Kaye and listened to his biofilm theory with interest.
"I'm something of an amateur paleontologist, as well," he said. "It's too bad that more people aren't working on this. But if I were going to guess I'd say Mary's work is going to stand the test of time."
Larry Martin, a paleontologist at the University of Kansas, was careful not to jump to conclusions in an interview with ScienceNews magazine published Wednesday.
The findings are "an interesting wake-up call," Martin told the magazine. He said the 2005 results could very well have been "just a badly misinterpreted artifact."
Schweitzer remained steadfast.
"There are a lot of problems with the science behind the paper," Schweitzer wrote, noting that Kaye's explanation is not supported by rigorous data. She said he failed to address all the evidence her team had used to support their soft-tissue hypothesis.
Schweitzer insisted that her results were well supported and reproducible by other scientists.
"Our multiple analyses conducted in different labs by different investigators supported the hypothesis that material consistent with collagen was preserved in these dinosaur tissues," she wrote. "I guess the best I can say is -- stay tuned!"
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