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FALL, 2006
Volume 50,
Number 1


Making the grade

Digging history


The University of Iowa
Digging history: Sloth discovery puts student volunteers to work

Two students examine sloth bones under a magnifying glass.
Students Meghann Mahoney, left, and Dana Callahan examine baby sloth bones in a Museum of Natural History laboratory.

Meghann Mahoney spent a chunk of her childhood mining for arrowheads and dinosaur bones in her backyard near Wellman, Iowa. Although she always came up empty-handed, a recent discovery as a  volunteer at the University of Iowa Museum  of Natural History has whetted her appetite  for paleontology.

QuoteLast spring, the UI junior was part of a small delegation scrutinizing a site in southwest Iowa where a giant Ice Age sloth was discovered in 2001. They hoped to recover additional bones from the same sloth, but what they discovered was even better: the shoulder blade of a baby sloth.

“That first glimpse of bone buried beneath the clay—what a moment of excitement. We knew the bone was too small to belong to the adult sloth,” recalls the anthropology major. “All of a sudden it didn’t matter how many times I’d been up to my knees in the muck, out in the hot sun.”

Mahoney is one of about a dozen student volunteers at the museum. Although excavation work has drawn considerable attention since the 2001 sloth discovery, volunteers perform a range of duties, from greeting visitors and leading tours, to cleaning glass and creating exhibits.

The work is available to students of all majors, says museum curator David Brenzel, noting that many volunteers come from art and theater backgrounds. The experience, he says, is invaluable for undergraduates as they poise themselves for the job market.

“Show me a job anywhere in the world that doesn’t require communication, organization, accomplishing a goal, or being comfortable talking with people,” he says. “These are  priceless skills that our volunteers get to  practice again and again.… And we simply  could not operate without our volunteers.”

Despite a lifelong interest in dinosaurs and history, and multiple visits to the museum as a child, Mahoney says it didn’t occur to her to volunteer at the museum until a friend did.

“I wasn’t sure if I really wanted to do excavation work (as a career),” Mahoney says, “so this has given me a good opportunity to figure that out and experience the excitement.”

Working behind the scenes at the museum reinforced Matt Kilberger’s desire to pursue graduate study in anthropology. The 2005 UI graduate spent countless hours in his senior year organizing more than 1,000 bone  fragments from the adult sloth’s shattered  pelvis. The anthropology major also earned  academic credit in geology for his efforts.

“When I first saw that smashed pelvis, I knew I wanted to work on it,” says Kilberger, now in graduate school at the University of Texas at Austin. “The first step was to take the dirt away with a dentist’s probe, and then eventually I tried to piece it together. My work on it lasted about a year, and it’s still not done. More than anything, the experience helped me to build patience.”

Although bones and artifacts are unearthed frequently in Iowa, the discovery of the sloth bones is unusual, Brenzel says, because sloth skeletons in good condition are rare.

“We have tens of thousands of mammoth bones, because elephants go to the water to die. They’re buried in the mud and therefore preserved,” he explains. “Giant sloths were common and widespread from coast to coast, but they were forest dwellers and their bones were scavenged. If you have 30 bones, you have a major find, and there were only five of those until now. What we found are two sloths that died in water.”

Several of the 30-plus baby sloth bones discovered last spring are on display in the museum, in an exhibit designed and constructed by work-study employees and student volunteers. The others are carefully spread out on tables in the museum’s laboratories on the ground floor of Macbride Hall. The goal now, Brenzel says, is to determine the correct sequence of the bones and to further excavate the site.

Count Mahoney among the volunteers to visit the sloth site again this fall. She says she’s spent so many hours cleaning and piecing together the baby sloth bones that she often jokes that it’s her baby.

“I’ve learned a lot about sloths,” she laughs. “This kind of work is like doing a puzzle when you’re missing half the pieces. It’s challenging  but it’s also fun. Finding something that is 10,000 years old and then sharing it with the world is an amazing feeling.”

For more information about the museum or  the sloth excavation, see

by Sara Epstein Moninger


Published by University Relations Publications. Copyright The University of Iowa 2004. All rights reserved.

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