"This information will help us learn more about evolutionary relationships, about how preservation happens, and about how molecules degrade over time, which could have important applications in medicine," Schweitzer said.
To see if the material had characteristics indicating the presence of collagen, which is plentiful, durable and has been recovered from other fossil materials, the scientists examined the resulting soft tissue with electron microscopy and atomic force microscopy. They then tested it against various antibodies that are known to react with collagen. Identifying collagen would indicate that it is original to T. rex--that the tissue contains remnants of the molecules produced by the dinosaur.
"This is the breakthrough that says it's possible to get sequences beyond 1 million years," said Cantley. "At 68 million years, it's still possible."
Asara and Cantley successfully sequenced portions of the dinosaur and mastodon proteins, identifying the amino acids and confirming that the material was collagen. When they compared the collagen sequences to a database that contains existing sequences from modern species, they found that the T. rex sequence had similarities to those of chickens, and that the mastodon was more closely related to mammals, including the African elephant.
The protein fragments in the T. rex fossil appear to most closely match amino acid sequences found in collagen of present-day chickens, lending support to the idea that birds and dinosaurs are evolutionarily related.
"Most people believe that birds evolved from dinosaurs, but that's based on the 'architecture' of the bones," Asara said. "This finding allows us the ability to say that they really a
Contact: Cheryl Dybas
National Science Foundation