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Philadelphia Museum's Fossil Surgeon Reveals Ancient Past

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    Philadelphia Museum's Fossil Surgeon Reveals Ancient Past
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    The three crates full of rocks traveled more than 10,000 miles by air and sea, from a barren Antarctic moonscape to a hallway outside Fred Mullison's cluttered workroom in Philadelphia.

    Scientists dug up the rocks, but until Mullison got his hands on them, no one could truly see the details of what they contained:

    Bony, armorlike plates from fish that lived nearly 400 million years ago. Teeth and spines from primitive sharks. Remnants of aquatic creatures with muscular "lobed" fins, similar to modern lungfish.

    Mullison is a fossil preparator at the Academy of Natural Sciences of Drexel University. Wielding a carbide needle, he delicately chips away bits of sediment to reveal ancient bones trapped inside.

    "This is a simple process," he said. "You follow the bone and remove what's not bone."

    Simple in concept, maybe, but his scientific colleagues say there are few who could exceed his pinpoint precision and intense focus. Mullison sits for hours at a time, peering at rocks through a microscope as he exposes their secrets, his right hand guiding the needle with almost imperceptible movements.

    "He's taking the rock apart grain by grain," said academy paleontologist Edward B. Daeschler, a member of the team that dug up Antarctic rocks in December and January. "I don't have that kind of patience."

    No cellphone

    Mullison, 65, keeps distractions to a minimum. He has no cellphone. He drives from his home in Kennett Square every morning to start work at 7:30, slipping in through the academy's side door on 19th Street, long before the busloads of schoolchildren arrive to gawk at the celebrated dinosaurs and wildlife dioramas.

    After a first career as a commercial photographer, Mullison has been working on fossils for more than 20 years, a behind-the-scenes participant in discoveries that have reshaped the tree of life.

    The biggest, in 2006, came from the other end of the world, hundreds of miles north of the Arctic Circle. That was Tiktaalik roseae, a fishlike creature with muscled fins that likely enabled it to wriggle onto land for short stretches.

    Daeschler was part of that team, too.

    The big find meant Daeschler was in demand for media interviews and TV appearances. Research partner Neil Shubin, a paleontologist at the University of Chicago, followed with a book and PBS series titled Your Inner Fish. (A key point: certain fish from that era, the Devonian period, are the ancestors of humans and all limbed animals.)

    The man who gently scraped the rock off the fossils — so the scientists could tell what they had — was content with a mention in small type at the end: "Specimens were prepared by C. F. Mullison."

    He had no interest in going on the expeditions, either to the Arctic or the Antarctic.

    "I'm not a winter-type guy," he said, chuckling.

    Yet he is keenly interested in the science, having audited classes in anatomy and evolution at the University of Pennsylvania. He can point out the features of prehistoric creatures with ease, and he has accompanied Daeschler on fossil hunts in north central Pennsylvania, another rich source of prehistoric deposits.

    It all began in 1995. Mullison was growing weary of photography, which had started to seem too much like a job and less like the creative pursuit he enjoyed as a fine-arts major at Carnegie Mellon University. During a visit to the academy, a girlfriend suggested he volunteer there.

    He was given a shot at preparing fossils, and proved to be so good at it that they found grant money to pay him. The job was part-time at first, then became full-time in 1999.

    "It's all serendipity," he said. "Nobody goes to college and thinks they're going to be a fossil preparator."

    But a fine arts background is common in the field. It requires the innate talents of an artisan, said Mullison, who also studied goldsmithing and silversmithing in Carnegie Mellon's sculpture department.

    He likened it to that football maxim that you can't coach speed. Either you have the steady hand, dexterity, and discipline needed to work with fossils, or you don't.

    "When it comes to biology, you can learn that," he said.

    A millimeter at a time

    He demonstrated his technique recently with a specimen from Daeschler's Antarctic trip. First, he painted on a few dabs of solvent, dissolving a "consolidant" chemical that Daeschler and colleagues had applied in the field to hold the rock together.

    For removing large sections of rock — "large," by Mullison's definition, means an inch or two — he uses miniature, handheld jackhammers called air scribes. This specimen required fine-scale work, removing a millimeter of rock at a time, so Mullison used his needle.

    Though the exact species is still unclear, the team already can see enough bone to determine that it belongs to a broader category called Bothriolepis, a fish with a bony head shield that resembles the visor on a knight's helmet. Various species of these fish have been found all over the world, including the Canadian Arctic.

    Both the Antarctic and Arctic sites were located closer to the equator when these fish were alive, and the climate was much warmer than it is today. Studying the fossils enables scientists to reconstruct a picture of the world in eons past.

    Sometimes the bone is harder than the surrounding rock, but the Bothriolepis specimen was the opposite. "The bone is soft and punky," he said, picking at the surrounding "ornery" rock with extreme caution.

    At least the fossil was white, making it stand out against the hard, dark-gray stone.

    Sometimes, it is difficult to tell where rock ends and bone begins. It is a given that a fossil preparator will destroy 1 percent to 2 percent of the specimen when removing the surrounding rock, Mullison said.

    Daeschler is not concerned, as he waits to see what Mullison gives him so he can analyze the bones to see if a new species has been found.

    "We trust him 100 percent," the scientist said, "to pull as much information as possible from the rock."

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    Information from: The Philadelphia Inquirer, http://www.inquirer.com