Crinoid Capitol of the World

(A sign reads “Des Moines County Heritage Center, Des Moines County Historical Society.”)

[Abby Brown] Ten Iowa counties are located along the Mississippi River, but only one is the crinoid capital of the world. What's a crinoid and why are they here? Let's go investigate.

(Map marking Des Moines County in southeast Iowa.)

Millions and millions of years ago, a shallow sea covered Iowa. How do we know that? Because we have evidence.

These are crinoid fossils.

(An acorn-like shell, sand-like in color and texture with starfish-like cutouts all along the top and sides.)

(An acorn-like shell with a tan top and a bumpy, cottage cheese-like white underside.)

Crinoids are ancient marine animals that first appeared 300 million years before dinosaurs.

Over time, as they died, along with other sea organisms, their remains were fossilized, in the Earth, eventually helping to form limestone.

Lots of different kinds of ocean fossils can be found in the limestone in Iowa. So many were discovered here because when Iowa was first becoming a state, the limestone here was mined for building materials. Mining means digging, and digging revealed long-buried fossils.

Kenneth and Linda Tibbetts collected crinoid and blastoid fossils they found in a geological formation known as Burlington Limestone.

After 40 years of collecting, they had over 3,000 fossils, which was one of the biggest collections in the world.

A few years ago, they donated their fossils to the Des Moines County Heritage Museum, who created the Hall of Crinoids.

The Tibbits knew that donating their collection here was awesome, not only because this area is geologically famous for these types of fossils, but also because they knew it would be the world's largest public exhibit of crinoid fossils.

Admiring all these fossils and knowing they were removed from limestone that had formed layer by layer over millions of years, you'd think crinoids would be long extinct, right? Nope.

About 600 species of crinoids are alive today. They actually haven't changed too much over their millions of years of existence.

(A palm tree-like crinoid with many dark octopus-like tentacles waving in the ocean current.)

However, they now have the ability to move in search of favorable ocean currents. Pretty cool, huh?

(A skeleton, crab-like crinoid with many bone-like tentacles going every which way crawling across the ocean floor.)

Thanks to people who were determined to display the lifelong findings of fossil-loving collectors, Iowans are able to see firsthand what life forms inhabited the shallow sea that once covered the land we call home.

Every county in Iowa has science layered in its history. Here in Des Moines County, those layers are showcased in an amazing collection of sea fossils.

Funding for FIND Iowa has been provided by The Coons Foundation, Pella and the Gilchrist Foundation.