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INTRO: When a radiologist at the Kodiak, Alaska, medical center needed to test a new, state-of-the art CT scanner, he enlisted the help of a most unlikely patient. As Doug Schneider reports in this week's Arctic Science Journeys Radio, this modern x-ray machine and the Internet recently joined forces to identify a 15-million-year-old fossil.
STORY: It started out innocently enough. Some five years ago, Kodiak, Alaska, residents Walter McFarland and his grandson, Lenni Hegli, found what looked like the fossilized skull of a Steller sea lion. Steller sea lions are common around Kodiak, so not much was made of the discovery. Instead, the 30-pound hunk of rock laid around the McFarland's home—more a conversation piece than anything else.
Then just recently, Dr. Hans Tschersich (pronounced: chair-sick), a radiologist at Kodiak's Providence Medical Center, heard about the fossil. A bit of a science buff himself, Tschersich got hold of the skull and asked Kate Wynne, a marine mammal expert at the University of Alaska Sea Grant Program, if it was that of a sea lion.
WYNNE: "It was definitely a mammal-looking skull, but it was a shape that I'd never seen before. It was a flatter, more triangular-shaped skull than I'd ever seen."
Being a radiologist, Tschersich decided to run the skull through the hospital's brand new CT scanner, a specialized x-ray machine usually reserved for imaging the insides of the human body.
TSCHERISCH: "Well, we had this new CT scanner and we needed to play around and practice with it. We used it as one of our practice patients, let's say."
Tschersich put the CT images, along with photographs he took of the skull, onto his personal web site. He then contacted Dr. Louie Marincovich, a paleontologist at the California Academy of Sciences in San Francisco. Instantly, Marincovich knew the fossilized skull was something special.
MARINCOVICH: "I think it is called Desmostylus, and it's an ancient sea cow that's no longer alive. It's an extinct species."
Marincovich says a molar tooth protruding from the skull was a dead giveaway. Large, flat, and worn, he'd found such teeth before, ironically, near the same beach where this skull was discovered. But Marincovich doesn't know much about the animal itself, other than that it lived some 15 million years ago. For more information, we called on Dr. Charles Repenning, a research associate with the Denver Museum of Natural History. Repenning says the skull is that of a juvenile, belonging to a group of early marine mammals called desmostylians.
REPENNING: "It had four legs but it was very marine-adapted. They legs were obviously adapted in peculiar angles to make the legs into flippers or paddles. There's been a lot of speculation as to how they may have walked on land, but nobody has ever established as fact that it actually did walk on land"
At least four kinds of desmostylians have been identified, two of them in Alaska. Repenning says further measurements of the molar tooth should confirm whether it is actually a desmostylus or another kind, called cornwallius.
But either way, desmostylians were vegetarians that foraged on the lush carpet of marine grasses that grew in shallow water along the sea's edge. That much was easy to figure out, says Repenning. Tracing the animal's exact lineage is more difficult. Turns out, while desmostylians bore superficial resemblance to today's hippopotamus, their distant relative is actually elephants.
REPENNING: "That gets a little unbelievable. The current thinking—that is for the past 100 years—is that it is fairly closely related to the elephant, but it is marine, although the fossil record doesn't trace it very well."
Although these ancient marine mammals lived throughout the North Pacific Ocean, finding anything more than their teeth is rare. Finding a skull is rarer still. Repenning says the National Museum in Washington, D.C., would likely want to have the skull in its collection.
While the skull is fascinating discovery in itself, there's another aspect of this story that's equally interesting. That's the role played by the Internet in identifying the skull.
REPENNING: If someone told me what they found, I wouldn't have been able to identify it, but after seeing it on the Internet I could tell what it was."
OUTRO: This is Arctic Science Journeys Radio, a production of the Alaska Sea Grant Program and the University of Alaska Fairbanks. I'm Doug Schneider.
For more information about Desmostylus, visit these web pages:
Read more about desmostyilians from Dr. Charles Repenning.
Thanks to the following individuals for help preparing this script:
Dr. Charles Repenning
Hans U. Tschersich, MD
Dr. Louie Marincovich
Kate Wynne, Marine Mammal Specialist
Arctic Science Journeys is a radio service highlighting science, culture, and the environment of the circumpolar north. Produced by the Alaska Sea Grant College Program and the University of Alaska Fairbanks.
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