Mammoth Discovery--UI involved in ongoing excavation of mammoth skeleton

Two years ago, an Iowa farmer and his sons were out looking for berries near their home in Oskaloosa when they stumbled on what appeared to be an enormous bone sticking out of the dirt. It turned out to be a mammoth bone—and potentially the most important mammoth discovery in Iowa.

The family recently enlisted University of Iowa experts to aid in the excavation. The UI Museum of Natural History, with the cooperation of the Department of Geoscience and the Office of the State Archaeologist, has organized an ongoing excavation and scientific evaluation of the find. So far nearly 50 bones have been recovered, including an impressive femur, multiple ribs and vertebrae, and a few toe bones. The discovery of both large and small bones within the same area is important as it means the mammoth was buried where it died, with little bone displacement—the entire skeleton may still be in the same area.

Although mammoth bones aren’t too uncommon in this area, finding a mostly complete, largely undisturbed skeleton is extremely rare. While there are quite a few records of mammoths from Iowa, almost all are individual bones. To learn more about how this mammoth lived, researchers will test the bones for carbon, nitrogen, and oxygen isotopes. Soil and botanical samples also have been taken to help identify how the land looked when the animal roamed Iowa.

Click on the thumbnail images below to get a glimpse of the excavation and its discoveries.

—Miles Dietz
photos by Tom Jorgensen

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The dig site is located along a creek on a family farm near Oskaloosa, Iowa.Art Bettis, UI associate professor of geoscience, takes a core sample of the site with the help of Phil Kerr, an undergraduate studying geoscience.Frank Weirich, UI associate professor of geoscience, and graduate student Megan Schetter map the area below the surface using ground-penetrating radar, which allows them to construct a 3-D computer model of anything buried below.The group carefully digs by hand.Art Bettis, UI associate professor of geoscience, discovers a small bone fragment.

The fragment of mammoth bone will be positively identified later on the UI campus by Holmes Semken, UI professor emeritus of geoscience.Sarah Horgen, education coordinator at the UI Museum of Natural History, records the exact location where the bone was found.The landowner, identified only as John, compares notes with Horgen, describing where he thinks a rib is located.The two unearth the edge of the rib, which will be left in place to allow a group of children from the Indian Creek Nature Center in Cedar Rapids the opportunity to remove the specimen from the site.Holmes Semken (left), UI professor emeritus of geoscience, and David Brenzel (right), a teacher-naturalist at the Indian Creek Nature Center, discuss where the next excavation should be located.

John is guided by his son Jared as he uses a backhoe to remove soil to the depth where other mammoth bones have be found. He is also creating a level shelf for the next ground-penetrating radar survey.Holmes Semken, UI professor emeritus of geoscience, talks about pieces of tusk found on site and answers questions as scientists and volunteers arrive at the farm the morning of the dig.A mammoth scapula or shoulder bone was found at the site.The day's dig gets started.Two volunteers use probes to penetrate the surface. When the probe hits an object below, a flag is placed to mark the spot for excavation. Notice the pattern of holes created by the probe.

An object found by the probe is unearthed, and soil gently removed. In this case, it is just a rock.Red flags mark the spots where dense objects were located under the surface. The blue-grey clay layer seen next to the trowel and the red flag is the same material in which other bones have been found.Buckets of material removed while excavating are carried to be screened by volunteers who look for bone fragments and other objects.Tools used at the dig.



© The University of Iowa 2009