Which Dinosaurs and Prehistoric Animals Lived in Iowa?

A skeleton of the Woolly Mammoth, a prehistoric mammal that lived in Iowa

Sylvain Sonnet / Getty Images

Unfortunately for dinosaur enthusiasts, Iowa spent much of its prehistory covered with water. This means that dinosaur fossils in the Hawkeye State are scarcer than hen's teeth, and that Iowa doesn't have much to boast about when it comes to the examples of megafauna mammals of the later Pleistocene epoch, common elsewhere in North America. Still, that doesn't mean that Iowa was entirely bereft of prehistoric life.

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Duck-Billed Dinosaurs

The skeletons of two duck-billed dinosaurs, Hypacrosaurus altispinosus

Chesnot / Getty Images

You can hold all of the fossil evidence for dinosaur life in Iowa in the palm of your hand. A few tiny fossils that have been attributed to hadrosaurs like hypacrosaurus, duck-billed dinosaurs that lived during the middle Cretaceous period about 100 million years ago. Since we know that dinosaurs were thick on the ground in neighboring Kansas, South Dakota, and Minnesota, it's clear that the Hawkeye state was also populated by hadrosaurs, raptors, and tyrannosaurs. The trouble is, they left virtually no imprint in the fossil record!

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A plesiosaur reptile skeleton in a Canadian Museum

Richard Cummins / Getty Images

Similar to the case with Iowa's dinosaurs, plesiosaurs also left behind fragmentary remains in this state. These long, slender, and often vicious marine reptiles populated the Hawkeye State during one of its numerous times underwater, in the middle Cretaceous period. A typical plesiosaur, like elasmosaurus, resembles artistic depictions of the Loch Ness Monster. Sadly, the plesiosaurs discovered in Iowa are unimpressive indeed when compared to those unearthed in neighboring Kansas, which is famous for its fossilized evidence of an extremely rich and varied marine ecosystem.

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Whatcheeria deltae, a prehistoric animal named for What Cheer, Iowa

Dmitry Bogdanov / Deviant Art / CC BY-NC-ND 3.0

Discovered near the town of What Cheer in the early 1990s, Whatcheeria dates to the end of "Romer's Gap," a 20-million-year stretch of geologic time that has yielded comparably few fossils of any kind, including tetrapods (the four-footed fish that began evolving toward a terrestrial existence over 300 million years ago). Judging by its powerful tail, Whatcheeria appears to have spent most of its time in the water, only occasionally crawling up onto dry land.

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Woolly Mammoth

The Woolly Mammoth, a prehistoric mammal distantly related to the modern elephant, left fossil remains in Iowa

Flying Puffin/FunkMonk / Wikimedia Commons/Flickr / CC BY-SA 2.0

In 2010, a farmer in Oskaloosa made an amazing discovery: the four-foot-long femur (thigh bone) of a woolly mammoth, dating to about 12,000 years ago, or the very end of the Pleistocene epoch. Since then, this farm has been a beehive of activity, as researchers excavate the remainder of this full-grown mammoth and any companions that might happen to have fossilized nearby. Bear in mind that any area with woolly mammoths likely was home to other megafauna, the fossil evidence for which has yet to come to light.

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Corals and Crinoids

Pentacrinites fossilis, fossils of starfish-like crinoids

joeblogs8282 / Flickr / Public Domain


Around 400 million years ago, during the Devonian and Silurian periods, most of modern-day Iowa was submerged under water. The city of Coralville, north of Iowa City, is renowned for its fossils of colonial (i.e., group-dwelling) corals from this time period, so much so that the responsible formation is known as the Devonian Fossil Gorge. These same sediments have also yielded the fossils of crinoids like pentacrinites: small, tentacled marine invertebrates vaguely reminiscent of starfish.

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Strauss, Bob. "Which Dinosaurs and Prehistoric Animals Lived in Iowa?" ThoughtCo, Aug. 29, 2020, thoughtco.com/dinosaurs-and-prehistoric-animals-of-iowa-1092073. Strauss, Bob. (2020, August 29). Which Dinosaurs and Prehistoric Animals Lived in Iowa? Retrieved from https://www.thoughtco.com/dinosaurs-and-prehistoric-animals-of-iowa-1092073 Strauss, Bob. "Which Dinosaurs and Prehistoric Animals Lived in Iowa?" ThoughtCo. https://www.thoughtco.com/dinosaurs-and-prehistoric-animals-of-iowa-1092073 (accessed June 7, 2023).