2.3" Ordovician Cephalopod and Gastropod Association - Wisconsin

This is a 1.7" long example of the straight-shelled cephalopod, Proteoceras sp. and a Trochonema gastropod fossil. This specimen is part of a collection from the Grand Detour Formation in Rock County, Wisconsin. Proteoceras was one of few species of straight-shelled cephalopods. It is a partial shell embedded in stone. There are other marine fossils embedded in the rock as well.