The University of Iowa Museum of Natural History will bring the Ice Age to life in Shenandoah, Iowa, on Saturday, May 30 with a day of free public activities based on the nearby Tarkio Valley Ice Age sloth excavations at the Greater Shenandoah Historical Society Museum, 800 West Sheridan Ave.

The day's events, which will be held from 10 a.m. to 3 p.m., are part of the museum's 150th anniversary celebration and include the first-ever public display of the Tarkio Valley sloth toddler with bones from the adult and baby. Other activities will include a video showing footage from the site, a slide show on the history and future of the Tarkio Valley, an "artifact road show" where visitors can bring fossils and artifacts to an expert for identification (no appraisals will be given), and a hands-on activity table for children.

The Tarkio Valley Sloth Project -- an ongoing excavation of three giant Ice Age sloths called Megalonyx jeffersonii -- recently identified a bone from a fourth sloth near the site, this one from a type of sloth never before recorded in Iowa, called Paramylodon harlani. Ice Age sloth expert Greg McDonald, the senior curator of natural history for the National Park Service's Park Museum Management Program and a consultant on the Tarkio Valley project, identified the approximately 5-inch long bone as the animal's fifth metacarpal, which once connected its wrist to its little finger, during a visit to the museum last week.

Both Paramylodon and Megalonyx were nearly elephant-sized Ice Age mammals that became extinct about 12,000 years ago. But Paramylodon sloths were equipped with broader, triangular claws for digging rather than the sharp claws of the Megalonyx, which were used for grabbing at woody vegetation like tree branches, McDonald said.

The new sloth identification came on the heels another major excavation discovery at the original site on April 25, when three more major Megalonyx bones were discovered. Holmes Semken, project leader and emeritus professor in the UI Department of Geoscience, and David Brenzel, another primary investigator for the project, identified the findings on site as a scapula (shoulder blade) from the baby sloth -- only the second recovery from this specimen -- and two rib bones from the older toddler sloth.

"Of all of the Megalonyx sites discovered, the Tarkio specimens will provide the basis for the most comprehensive analysis of sloth paleobiology and ecology of any to date," said McDonald, whose visit was made possible by a recent $20,000 National Science Foundation grant awarded to the project to complete excavation and begin more wide-ranging research on the discovery.

McDonald estimated that the approximately 110 bones recovered from the adult Megalonyx represent about 60 percent of the full skeleton, making it the second most complete of its kind. Only six other semi-complete skeletons of this species have ever been found, none of which are associated with younger animals. The older juvenile is also the second most complete of its kind, with more than 40 bones recovered.

The skeletons have the added research benefit of being buried in sediments that will provide valuable environmental data about the climate and ecology during the sloths' lives.