High-tech tools link T. rex to chickens

Call it the paleontological equivalent of squeezing blood from a stone.

Using highly sensitive instruments and techniques more typically employed to study human disease, scientists at Harvard Medical School have for the first time isolated and identified proteins from a dinosaur, a tyrannosaurus rex that roared its last 68 million years ago.

Some proteins identified in the ferociously fanged Cretaceous-era predator were a close match to protein found in modern-day chickens, which the authors say lends more credence to theories that birds are descended from dinosaurs.

The findings, being published in two articles in Science magazine today, shattered the long-held assumption that protein and other basic materials of life could not possibly survive in detectable amounts for more than a few hundred thousand years. The research also raised the possibility that scientists might eventually recover DNA from prehistoric beasts, allowing for an even more sophisticated analysis of ancient organisms and the processes of evolution.

"People are going to be looking differently at prehistoric bones because now we see they may carry tissue and information that nobody believed could still exist," said Mary Higby Schweitzer, a paleontologist at North Carolina State University and a coauthor of both articles.

Scientists at Harvard were able to isolate seven tiny strips of collagen protein from soft tissue found in the thigh bone of a tyrannosaurus rex fossil recovered earlier in the decade from beneath 60 feet of sandstone ledge in Montana's Hell Creek formation.

"At the very least, this breakthrough shows we can look at [protein] sequences that are many, many millions of years old," said John M. Asara, director of the mass spectrometry core facility at Beth Israel Deaconess Medical Center and a lead researcher on the experiments. "That's a first."

The same researchers also reported that they isolated 70 protein sequences from a mastodon that died more than 160,000 years ago. Until now, the oldest positively-identified proteins were recovered from the bones of a mammoth reckoned to be a couple of hundred thousand years old, according to Schweitzer. DNA has been taken from the 38,000-year-old bones of a Neanderthal, believed to be a prehistoric relative of modern humans.

Paleontologists not involved in the T. rex protein research said it represented an astonishing piece of scientific sleuth work.

But there was doubt whether the experiment will have much practical effect on the study of prehistoric life. There may never be enough dinosaur soft tissue discovered for meaningful scientific scrutiny.

"If there were regular opportunities for this kind of matching and comparison, [these] techniques might add important evidence to genuine conundrums -- outstanding questions about the origin and relationships of various vertebrate groups," said Farish A. Jenkins Jr., a Harvard zoology professor and internationally recognized specialist in vertebrate paleontology. "But the reality remains that finding soft tissues preserved with actual soft-tissue structure intact is outside the realm of common expectation."

Similar skepticism was expressed by Mark A. Norell, a paleontologist with the American Museum of Natural History: "This is a very cool experiment," he said, "but I don't think curators are going to start grinding up their fossil bones to obtain the really minuscule bits of protein that might be available. Science requires replication. You need thousands of comparisons. Not dozens."

Famed fossil hunter John Horner, a paleontologist at Montana's Museum of the Rockies and the discoverer of the T. rex fossil that yielded the protein, disagreed. "We're just going to have to look harder for bigger, exquisitely preserved specimens," he said.

Spurred by the protein identifications on the T. rex, Horner said, nine teams of more than 100 fossil seekers will fan out from Montana to Mongolia this summer in search of substantial dinosaur remains that might contain soft tissue.

The T. rex research marked an unusual collaboration between field paleontologists, famous for rough expeditions to remote places, and medical researchers more familiar with lab equipment than pickaxes.

The dinosaur femur at the center of the research was found in 2003. Schweitzer, analyzing the fossil, found evidence that it contained actual bone and vascular tissue -- not just the minerals that replace organic matter in the fossilization process.

Reading of her discovery, Lewis Cantley, a cancer specialist and professor of systems biology at Harvard Medical School, wondered whether protein sequences might be identified if dinosaur tissue was fed into Harvard's Thermo Scientific LTQ mass spectrometer, which measures and otherwise identifies proteins.

He put the challenge to Asara, whose main job is using spectrometry to study human disease.

"We were almost half-joking at the outset," said Asara. "But I also knew I wasn't going to stop until I found something."

Asara started with about 40 milligrams of gritty, brownish powder extracted from the T. rex tissue. Purging it of contaminants and the painstaking analysis of the resultant microscopic bits took a year and a half. Cantley said techniques used in sequencing the dinosaur protein from minuscule amounts of material could be useful for researchers who need to find the tiny molecular changes that lead to tumors.

Scientists were quick to discount any suggestion that the sequencing of protein from a T. rex might represent a first step toward cloning dinosaurs, as in Michael Crichton's novel "Jurassic Park" and the movies that followed. Cloning would require DNA, which deteriorates more rapidly than protein.

"The idea of cloning prehistoric animals from genetic materials remains science fiction," said Lawrence M. Witmer, an Ohio University paleontologist. "But keep in mind, until very, very recently, just the idea of obtaining any genetic material at all from animals so old was dismissed as pure science fiction."

Colin Nickerson can be reached at nickerson@globe.com.