450 million years in the making. Discovered during a moment of engineering history. Celebrated as a state symbol.
In the spring of 1919, while digging deep into the bedrock for Huffman Dam’s outlet structure, a construction crew with the Miami Conservancy District made a truly extraordinary discovery: a perfectly preserved, 14-inch trilobite—the largest complete specimen of its kind ever found.
Nicknamed “Pete” by the press, this Isotelus trilobite is a relic of an ancient marine world that covered Southwest Ohio hundreds of millions of years ago during the Ordovician Period. The shale that once encased it had been buried far below the modern-day Mad River—until flood protection engineering brought it back to light.
The fossil quickly became a local and national sensation, drawing the attention of paleontologist August Foerste of Dayton. After months on display in downtown Dayton and at the Miami Conservancy District’s offices, Pete was carefully transported to Washington, D.C., where it remains in the collections of the Smithsonian Institution’s National Museum of Natural History.
This iconic fossil discovery is a powerful reminder of how MCD’s work—begun in response to the catastrophic 1913 flood—has unexpected connections not only to public safety, but also to science, education, and Ohio’s deep-time story.
Fun Fact: In 1985, thanks in part to this discovery, Isotelus was officially named Ohio’s State Invertebrate Fossil.
