Hagerman's Giant Marmot
Anyone traveling through southern Idaho has seen them by the side of the road, or often, running across the road playing "chicken" with your car. They are the largest living member of the squirrel family and are known locally as rockchucks, a western relative of the well known woodchuck or ground hog, who gets national attention every February 2. The rockchuck or yellow-bellied marmot, Marmota flaviventris, is found throughout the western United States and can be found in a variety of environments from desert to mountain.
Many visitors to the area are amazed by the size of the largest of all ground squirrels, 3.9 kilograms (8.5 pounds) on the average although some individuals will get as large as 5.2 kg (11.5 pounds). Had people been visiting Hagerman Fossil Beds 3.5 million years ago they would have been even more amazed at the size of the fossil marmot, Paenemarmota barbouri, found here.
It was roughly twice the size of our living yellow-bellied marmot. The giant marmot was first described in 1948 based on a specimen found in Kansas. During the Pliocene, it was widely distributed in western North America and has also been found in Nebraska, Texas, Arizona and northern Mexico. It was not reported from Hagerman until 1969. The Hagerman record is currently the most northern and western record for the animal.
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This article originally appeared in The Fossil Record, Summer 1998
Did You Know?
Lake Bonneville overflowed its rim about 15,000 years ago in southeastern Idaho near the present day city of Pocatello. The Snake River cut down through the ancient flood plain sediments and deepened and widened the Hagerman valley.