The Dinosaurs and Prehistoric Animals of Wisconsin

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Which Dinosaurs and Prehistoric Animals Lived in Wisconsin?

The American Mastodon, a prehistoric mammal of Wisconsin. Wikimedia Commons

Wisconsin has a lopsided fossil history: this state teemed with marine invertebrates until the late Paleozoic Era, about 300 million years ago, at which point the geologic record comes to a screeching halt. It's not that life in Wisconsin went extinct; it's that the rocks this life would have been preserved in were actively eroded away, rather than deposited, up until the cusp of the modern era, meaning that no dinosaurs have ever been discovered in this state. Still, this doesn't mean that the Badger State was entirely devoid of prehistoric animals, as you can learn by perusing the following slides. (See a list of dinosaurs and prehistoric animals discovered in each U.S. state.)

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Calymene, a trilobite of Wisconsin. Wikimedia Commons

The official state fossil of Wisconsin, Calymene was a genus of trilobite that lived about 420 million years ago, during the Silurian period (back when vertebrate life had yet to invade dry land, and ocean life was dominated by arthropods and other invertebrates). Numerous specimens of Calymene were discovered in Wisconsin in the early 19th century, but this ancient arthropod didn't receive official government recognition until 150 years later.

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Small Marine Invertebrates

Fossilized brachiopods. Wikimedia Commons

Geologically speaking, parts of Wisconsin are truly ancient, with sediments dating back over 500 million years to the Cambrian period--when multicellular life was just beginning to flourish and "try out" new body types. As a result, this state is rich in the remains of small marine invertebrates, ranging from jellyfish (which, since they're composed entirely of soft tissue, are rarely preserved in the fossil record) to corals, gastropods, bivalves and sponges.

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Mammoths and Mastodons

woolly mammoth
The Woolly Mammoth, a prehistoric mammal of Wisconsin. Heinrich Harder

Like many other states in the central and western United States, late Pleistocene Wisconsin was home to thundering herds of Woolly Mammoths (Mammuthus primigenius) and American Mastodons (Mammut americanum), until these giant pachyderms were rendered extinct at the end of the last Ice Age. The fragmentary remains of other megafauna mammals, such as ancetral bison and giant beavers, have also been discovered in this state.