Ungual claw from indeterminate theropod where the possible blood cells were found. (Laurent Mekul)

A 75 million-year-old dinosaur fossil -- and a poorly preserved one, at that -- may have yielded traces of intriguing soft tissue. Scientists believe they've spotted blood cells and collagen, the protein that makes up connective tissue in animals. Their findings were published Tuesday in Nature Communications.

[Dinosaurs aren’t really extinct (sorry, 'Jurassic Park')]

Years ago, researcher Mary Schweitzer found what she believed were preserved blood vessels in a T. rex bone, a finding that has since been supported by molecular analysis. But unlike the specimen Schweitzer worked with, the fossils used in the new study were poorly preserved, which suggests that soft-tissue preservation might not be as uncommon as we'd thought. However, further evidence is needed to confirm that the structures are what they appear to be.

[Scientists did an autopsy of a ‘T. rex’ on TV and it was awesome (and bloody)]

The fossils, the researchers explained, are "cr--" by necessity. To go looking for soft tissue and other interesting remnants, the researchers had to snap bits off fossils to look at their unexposed insides.

“It’s really difficult to get curators to allow you to snap bits off their fossils. The ones we tested are cr--, very fragmentary, and they are not the sorts of fossils you’d expect to have soft tissue,” Susannah Maidment, a paleontologist at Imperial College and one of the study authors, told The Guardian.


Possible collagen fibers, taken from a rib and imaged with a scanning electron microscope. (Sergio Bertazzo)

When the team first spotted something that looked like blood in the remnants of a claw of a theropod dinosaur, they  assumed it was a contamination -- that someone had gone and bled on the fossil. But they were able to rule that out, because human blood cells don't have nuclei within them -- which these blood cells seem to have. Another sample yielded possible fibers of the collagen you'd see in bird bones -- or at least fibers containing the amino acids that could make that collagen.

Other researchers will need to confirm these fantastic finds. But if the research group is correct, it could mean that run-of-the-mill fossil collections all over the world have soft tissue waiting to be discovered. If researchers could study the blood vessels and other soft tissues of the dinosaurs, it could help us learn new things about them -- including how their metabolisms worked, which could finally end the debate on whether dinosaurs were warm blooded, cold blooded, or both.

[Dinosaurs may have been warm-blooded after all]

But "Jurassic-Park"-like DNA retrieval? Don't hold your breath.

Scientists found structures that appear to be red blood cells and protein despite the fossil's poor preservation. A new study suggests that the survival of soft-tissue may be far more common than researchers originally thought. (Bertazzo, et al./Nature Communications)

“This opens up the possibility of loads of specimens that may have soft tissue preserved in them," Sergio Bertazzo, a materials scientist at Imperial, told The Guardian. "But the problem with DNA is that even if you find it, it won’t be intact. It’s possible you could find fragments, but to find more than that? Who knows?”

Maybe one day scientists will be able to find the genetic information they need within fossils and order up brand new dinosaurs. But if that's in our future, it's still pretty far off.

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Dinosaurs aren’t really extinct (sorry, 'Jurassic Park')

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