[ComfortEagle]

WASHINGTON - A 70-million-year-old Tyrannosaurus rex fossil dug out of a hunk of sandstone has yielded soft tissue, including blood vessels and perhaps even whole cells, U.S. researchers reported on Thursday.

Paleontologists forced to break the creature's massive thighbone to get it on a helicopter found not a solid piece of fossilized bone, but instead something looking a bit less like a rock.

When they got it into a lab and chemically removed the hard minerals, they found what looked like blood vessels, bone cells and perhaps even blood cells.

"They are transparent, they are flexible," said Mary Higby Schweitzer of North Carolina State University and Montana State University, who conducted the study.

She said the vessels were flexible and in some cases their contents could be squeezed out.

"The microstructures that look like cells are preserved in every way," added Schweitzer, whose findings were published in the journal Science.

"Preservation of this extent, where you still have this flexibility and transparency, has never been seen in a dinosaur before." Feathers, hair and fossilized egg contents yes, but not truly soft tissue.

Studying the soft tissues may help answer many questions about dinosaurs. Were they cold-blooded like reptiles, warm-blooded like mammals, or somewhere in-between? How are they related to living animals?

"If we can isolate certain proteins, then perhaps we can address the issue of the physiology of the dinosaur," Schweitzer said.

Of course, the big question is whether it will be possible to see dinosaur DNA. "We don't know yet. We are doing a lot in the lab now that looks promising," Schweitzer said.

To make sure she was seeing what she thought she was seeing, Schweitzer, a biologist by training, compared the Tyrannosaur samples with bone taken from a dead ostrich. She chose an ostrich because birds are thought to be the closest living relatives of dinosaurs and ostriches are big birds.

Both the dinosaur and ostrich blood vessels contained small, reddish brown dots that could be the nuclei of the endothelial cells that line blood vessels.

Taking the minerals out of both ostrich bone and the Tyrannosaur bone — a simple experiment that can be duplicated by anyone using a chicken bone, for example, and vinegar — yielded flexible fibers. Microscopic examination showed what look like bone cells called osteocytes in both.


http://www.msnbc.msn.com/id/7285683/