68 Million-Year-Old T-Rex Tissue Sparks Major DNA Debate

Can DNA stand the test of time? The oldest proteins ever found are contained within the soft tissue of a T-Rex. Now, a scientific debate is brewing over the longevity of DNA.

Scientists have discovered the bones of 68 million-year-old Tyrannosaurus rex with soft tissue still intact. The find represents the oldest protein ever found, and it has allowed researchers to link the T-Rex to chickens. But skeptics wonder if the link is even possible. Chemical structures of the T-Rex tissue were compared with other species, and chickens provided the best match. The evidence adds growing support to the idea that chickens and other birds evolved from dinosaurs.

"I mean can you imagine pulling a bone out the ground after 68 million years and then getting intact protein sequences?" said John Asara of Beth Israel Deaconess Medical Center and Harvard Medical School, lead author of one of the studies. "That's just mind boggling how much preservation there is in these bones." Before the most recent find, the oldest protein every found was from a bone of a 100,000 to 300,000-year-old mammoth. But the DNA discovery will have skeptics talking because questions surround the longevity of tissues like these. "It's very, very, very controversial because most people have gone on record saying there's an absolute time limit to anything that's protein or DNA," said Mary Schweitzer, a molecular paleontologist at North Carolina State University Smithsonian Institution's dinosaur curator, Matthew Carrano, says that proteins are robust. "Here are the pieces of the protein. If you're going to refute this you have to explain how these pieces got in there," Carrano said in a telephone interview. "It's not another molecule mimicking the protein and giving off a similar signal. This is the actual sequence."