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December 1, 2007

Molecular Paleontology — In search of the real Jurassic Park

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Paleontologist Jack Horner is determined to find traces of dinosaur DNA among the fossils of Montana's badlands.

Most scientists think that's an impossibility.

Once upon a time they thought that about time travel, too — until Kurt Gödel sorted them out.

Here's Robert Lee Hotz's August 24, 2007 Wall Street Journal front page story about Horner and his quixotic, determined search for the past, captured.

    Dinosaur Hunter Seeks More Than Just Bare Bones

    Prof. Horner Searches For Traces of Blood, DNA; Lucky Break From T. Rex

    Prospecting in Montana's badlands, rock ax in hand, paleontologist Jack Horner picks up a piece of the jawbone of a dinosaur. He examines the splinter, then puts it back and moves on. It isn't the kind of bone he is looking for.

    Prof. Horner is searching for something that many scientists believe no longer exists: dinosaur bones that harbor blood cells, protein and, perhaps, even DNA.

    "Most people looking for dinosaurs are looking for beautiful skeletons," he says. "We are looking for information."

    This summer, Prof. Horner, 61 years old, is overseeing nine field expeditions, from Montana to Mongolia, looking for specimens intended not just for museums, but also for molecular studies. For more than a decade, he has been searching for soft tissue in dinosaur bones 65 million years old or more.

    His search for soft tissue places his fieldwork at the center of one of the most provocative endeavors in biology — the emerging field of molecular paleontology. With its emphasis on recovering ancient cells, the field offers the possibility of a chemical key that can unlock a living past, for any surviving cell could contain an organism's entire genetic blueprint.

    Until recently, the field was foundering on laboratory errors and spurious claims of genetic antiquity. So fragile is the chemistry of life that it can break down in a few months. But under just the right conditions, research now suggests, it can hold up for hundreds of thousands of years or more.

    Prof. Horner, a curator at the Museum of the Rockies in Bozeman, is among the world's most influential and offbeat paleontologists. He pioneered studies of dinosaur parenting behavior, species variation and bone cells. He is dyslexic, a former Special Forces operative of the Vietnam War era, a MacArthur Foundation "genius" fellow, and a chaired professor of Montana State University who never finished a formal college degree.

    "The lenses that people normally use to look at stuff are broken in Jack," says Mary Schweitzer, an assistant professor of paleontology at North Carolina State University, who has worked with him for years. "That's what makes Jack such a good scientist. Every now and then, every field should get a renegade weirdo in it who challenges assumptions."

    By their nature, even scholarly dinosaur studies are leaps of imagination. So it was with Prof. Horner's search for dinosaur tissue.

    In 1993, just as the film "Jurassic Park" was making its debut, the National Science Foundation announced that Ms. Schweitzer, then one of Prof. Horner's graduate students, had found hints of red blood cells in the femur of a Tyrannosaurus rex that he had excavated in eastern Montana.

    "Nobody believed us," recalls Prof. Horner, who also was the film's technical adviser.

    Then in 2003, one of his colleagues spotted a bone jutting from a 40-foot sandstone cliff not far from that first site. It was another Tyrannosaurus rex. It took four members of Prof. Horner's team two weeks working with jackhammers to free the skeleton.

    Jacketed in a protective sheath of plaster, one leg bone weighed two tons — far more than the crew's borrowed helicopter could lift. It started snowing. At wit's end, they sawed the priceless specimen in two.

    "I had this terrible sinking feeling while I was breaking this bone," says field engineer Nels Peterson. From the bone's core, several brownish fragments fell. He wrapped them in tinfoil.

    It turned out to be a lucky break. Two years later, Prof. Schweitzer announced she had found veins in the specimens and what looked like intact blood cells preserved inside the leg bone. And this past April, she, along with researchers at Harvard Medical School, reported they had identified proteins found inside that massive dinosaur femur — the oldest such biochemical data ever recovered.

    The upshot: Against all scientific expectation, there was fresh meat -- in microscopic quantities, to be sure -- in the hind leg of a dinosaur that had been dead for 68 million years.

    Such discoveries can help researchers understand creatures dead so long that no one really knows exactly what they looked like or how they behaved. They can reveal relationships between species extinct and living. The proteins extracted from the Tyrannosaurus leg Prof. Horner's team discovered most closely resembled those of a chicken, solidifying the idea that modern birds are direct descendants of dinosaurs. Minus its minerals, the bone from an emu was virtually identical in structure, orientation and color to the Tyrannosaurus bone.
    [Dinosaur]

    Even so, the Tyrannosaurus leg bone, the best preserved found so far, didn't yield any DNA. So much time in the earth had degraded the fragile biomolecules. For the foreseeable future, the idea of cloning a dinosaur is still safely science fiction.

    In tissue of younger species, though, scientists recently have pushed the boundaries of molecular paleontology further into the past.

    From a fossilized mastodon tooth found in Alaska, molecular biologist Nadin Rohland of the Max Planck Institute for Evolutionary Anthropology in Germany, extracted DNA between 50,000 and 130,000 years old, she reported this month in science journal PLoS Biology.

    In silt buried a mile deep in the ice cap of South Greenland, researchers in Denmark found DNA from pine trees and insects between 450,000 and 800,000 years old, they reported in Science in July. Before making their work public, the scientists made sure two other independent laboratories matched the DNA results.

    Earlier this month, researchers at Rutgers University and Boston University made public genetic sequences from the oldest DNA found so far. They extracted it from microbes 1.1 million years old, thawed after having been frozen in Antarctica. The DNA in bacteria from ice any older deteriorated quickly, they reported in the Proceedings of the National Academy of Sciences.

    Researchers think ice may favor preservation of fragile tissues and molecules of DNA, as also might extremely hot, arid conditions, like those found in the Montana badlands where Prof. Horner's teams are searching for soft tissue.

    "The chances of finding any [dinosaur] DNA are pretty low," Prof. Horner acknowledges. "I am still hopeful."

    In a field mostly outside the mainstream of federal research funding, Prof. Horner has a knack for attracting private grants. Star Wars producer George Lucas, Qualcomm co-founder Klein Gilhousen and Wade Dokken, a developer of Montana real estate, have contributed toward his research, the university says. Nathan Myhrvold, formerly chief technology officer at Microsoft Corp. and co-founder of Intellectual Ventures LLC, is helping to underwrite this season's fieldwork.

    This summer, in Montana's Hell Creek Formation, Prof. Horner is searching the last landscape inhabited by dinosaurs. More than 65 million years ago, this plain was a wetland where herds of horned Triceratops watered. Today, it is an arid outwash of boulders, cactus and sage. The red and gray soil is littered with white shards of petrified wood that ring like bone china when tapped together and countless crumbs of dinosaur bone.

    Packing 40 pounds of collection tools in the searing heat, Prof. Horner examines bones. The yellow bill of his "I Dig Dinos" baseball cap offers the only shade.

    Nearby, his crew is brushing sediment from the skeletal cowl of a Triceratops, too weathered to yield the pristine organic material that Prof. Horner seeks for cellular studies. Still, it is only the second specimen of such a young horned dinosaur known. It is museum-bound.

    Prof. Schweitzer is convinced that prehistoric molecules of cell protein — which are more robust than DNA and harder to contaminate — offer the most promising line of research. Prof. Horner keeps an open mind.

    "As long as you are not bound by preconceived ideas of what you can find," Prof. Horner says, "there are an awful lot of things you can discover."

December 1, 2007 at 04:01 PM | Permalink


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