The Dinosaurs and Prehistoric Animals of Iowa

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Which Dinosaurs and Prehistoric Animals Lived in Iowa?

woolly mammoth
The Woolly Mammoth, a prehistoric mammal of Iowa. Wikimedia Commons

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

Hypacrosaurus, a typical duck-billed dinosaur. Sergey Krasovskiy

You can literally hold all the evidence for dinosaur life in Indiana in the palm of your hand: a few tiny fossils that have been attributed to hadrosaurs, or 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 that they have left virtually no imprint in the fossil record!

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Elasmosaurus, a typical plesiosaur. James Kuether

Similar to the case with Iowa's dinosaurs, this state has yielded the fragmentary remains of plesiosaurs--the long, slender, and often vicious marine reptiles that populated the Hawkeye State during one of its numerous spells underwater, during the middle Cretaceous period. Sadly, the plesiosaurs discovered in Iowa are unimpressive indeed 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, a prehistoric animal of Iowa. Dmitry Bogdanov

Discovered near the town of What Cheer, Iowa, in the early 1990's, 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). To judge 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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The Woolly Mammoth

woolly mammoth
The Woolly Mammoth, a prehistoric mammal of Iowa. Wikimedia Commons

In 2010, a farmer in Oskaloosa, Iowa 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 mammals, the fossil evidence for which has yet to come to light.)

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Corals and Crinoids

Pentacrinites,a typical crinoid. Wikimedia Commons

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, small, tentacled marine invertebrates vaguely reminiscent of starfish.