American Mastodon

The American mastodon is Michigan's official state fossil, designated in 2002. Mammut americanum was a large proboscidean — related to mammoths and modern elephants but a distinct lineage — that browsed spruce and pine forests across North America during the Ice Age. Michigan is one of the richest states in mastodon remains, with hundreds of specimens recovered from glacial lake deposits and peat bogs.

The American mastodon stood about 8 to 10 feet tall at the shoulder and reached up to 15 feet in length, weighing between 8,000 and 12,000 pounds. It had long, slightly curved tusks and a heavy, low-slung body covered in thick brown fur. Its most distinctive trait was its teeth: mastodon molars had sharp cone-shaped cusps for chewing branches and leaves, unlike the ridged teeth of mammoths built for grinding grass.

Mastodons were browsers, feeding on the leaves, twigs, and shrubs of boreal forests. In Michigan they lived near the edges of glacial lakes and spruce swamps that covered the state as the last ice sheets retreated. They went extinct about 10,000 years ago along with most other large Ice Age mammals in North America.

Michigan school students played a direct role in the mastodon's designation. Students across the state petitioned the legislature in the late 1990s and early 2000s to give Michigan an official state fossil, pointing to the mastodon as the most fitting choice given how commonly its bones turn up in Michigan soil. The campaign succeeded in 2002 when the state legislature designated Mammut americanum.

The choice made scientific sense. Michigan sits atop some of the most productive mastodon territory in North America. The cold, boggy conditions left by retreating glaciers preserved mastodon bones for thousands of years, and ongoing construction, drainage, and farming continue to bring new specimens to the surface.

Mastodon remains have been recovered from nearly every county in Michigan's Lower Peninsula. The highest concentration comes from the southern tier of counties — Washtenaw, Oakland, Livingston, and Lapeer — where glacial kettle lakes and peat bogs preserved bones in waterlogged conditions. Farmers and construction crews continue to find mastodon teeth and bones during excavation.

The University of Michigan Museum of Natural History in Ann Arbor holds some of the state's most complete mastodon specimens and is the best place to see them up close. Michigan State University Museum in East Lansing also has notable material from the region.