T-Rex 'Tissue' May Be the Real Deal After All

Scientists are puzzled by the purported discovery of something they thought couldn't possibly still exist — bits of soft tissue from a Tyrannosaurus rex. Fossil-hunters found the matter two years ago, and skeptics have challenged its authenticity. But now there's new evidence suggesting the tissue is the real thing.

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Scientists are puzzling over a find they believed couldn't be possibly exist -bits of soft tissue from a dinosaur. Fossil hunters retrieved the tissue from the broken leg bone of a Tyrannosaurus rex. Skeptics have challenged its authenticity. But now, there's new evidence suggesting that the tissue is the real thing.

NPR's Christopher Joyce reports.

CHRISTOPHER JOYCE: A bedrock rule of paleontology is that there's no way soft tissue - skin, blood vessels, organs - can possibly last millions of years. But in 2003, fossil hunters dug up a 68-million-year-old Tyrannosaurus rex in Montana. They accidentally broke one of its bones and gave some fragments to Mary Schweitzer at North Carolina Sate University, and she's been studying the pieces ever since. In 2005, she found collagen - a fibrous material that's common in connective tissue in bones. Lots of experts didn't believe it, but now, scientists have recovered a tiny sequence of proteins from that collagen.

Dr. MARY SCHWEITZER (Professor of Paleontology, North Carolina University): The ultimate controversy is, can anything really exist for this long? And, with sequence data, we've taken a gigantic step forward in saying, yes, that it can.

JOYCE: Not that only are the proteins recognizable, their chemical structure can be read much the way DNA can be read. It's like an animal's molecular signature, says John Asara from Harvard Medical School. He says that after comparing the sequence from the T-Rex to those from 21 present-day animals, the team could place T-Rex on what you might call the evolutionary tree of life.

Dr. JOHN ASARA (Department of Pathology, Harvard Medical School): Based on this molecular data, it really suggests that the T-Rex is clearly closer to a bird than a reptile.

JOYCE: The team also did a similar analysis on tissue from a mastodon that's hundreds of thousands of years old. They found it closely related to elephants. These findings confirm what fossil hunting scientists already believed, dinosaurs and birds are closely related and so are mastodons and elephants. But the technique finding intact microscopic proteins from such ancient material is a first. Asara says it's not likely to happen very often.

Dr. ASARA: So it brings us - in order to basically find this protein, you really have to start with the bone that has exceptional preservation. And it's really amazing that we can get sequence at all from something that old.

JOYCE: But if the sequencing technique proves reliable, says Mary Schweitzer, it would give scientists a remarkable tool for reconstructing the biological past.

Dr. SCHWEITZER: The evolutionary story of how dinosaurs are related to one another and how they're related to modern birds and other animals, we can only determine so far from markings on the bone.

JOYCE: Protein sequences might even provide insight into the animals themselves, how their bodies worked, for example. But scientists will need more dinosaur bones with a lot more intact tissue. Those are rare, though Schweitzer says she may have already found some from another dinosaur. She acknowledges that she'll need more evidence to convince skeptics that these proteins are from some modern animal that somehow contaminated the specimen. And she herself remains puzzled at how the dinosaur collagen survived so long.

Dr. SCHWEITZER: Does it have something to do with the fact that these things are incorporated into bone? Does it have something to do with the dinosaurs? Does it have something to do with the environment at the time? I mean, we don't know.

JOYCE: The research appears in this week's issue of the journal, Science.

Christopher Joyce, NPR News.

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