T. Rex Closer to Gizzards Than Lizards

The results indicate that T. rex, chickens and ostriches are evolutionary siblings, all descended from a single unidentified predecessor. Alligator collagen is more distantly related, and lizard collagen is more distantly related still.

"Birds are a type of dinosaur the way Saint Bernards are a type of dog," Schweitzer said, "or like a poodle is a type of wolf."

A second analysis by the team backed up scientists' long-standing suspicions that extinct mastodons and modern-day elephants are close cousins.

Eddy Rubin, a geneticist and expert in ancient DNA who heads the Department of Energy's Joint Genome Institute in Walnut Creek, Calif., said he is "pleased to see" that the Harvard group was doing the hard work of duplicating and expanding upon its initial results, which were unusual not only because of the starting material but also because of the team's reliance on a novel method for analyzing tiny samples.

"Extraordinary results demand extraordinary evidence," Rubin said, conceding that in the past, at least, he "had some concerns" about the data.

"It's very exciting if they really are getting proteinaceous material from these terrifically ancient samples, because in some ways these sequences are time machines," Rubin said. "We can't go back in time, but these samples tell us things about these creatures that we can't tell from their bones and other features."

If further tests confirm a capacity to extract and accurately analyze smidgens of protein from fossilized remains, he and others said, it would be a boon to scientists who are trying to work out the branching pattern of the evolutionary tree of life.

Schweitzer said she welcomed challenges to their results. "If they can show our data are wrong, that's great," she said. "That is the way science progresses."

For his part, Asara said he is so sure of the results he can almost taste them.

"Based on this data," he said, "you can be very confident that T. rex would taste more like chicken than it did last year."