The Kimmswick Limestone is an Ordovician geologic formation in Arkansas, Illinois, and Missouri that preserves fossils from an ancient marine environment. Its fossil record includes corals, bryozoans, brachiopods, conodonts, trilobites, crinoids, and mollusks. Reported trilobites from the formation include Eobronteus and E. slocomi. Because it contains such a broad range of fossil groups, the Kimmswick is an important unit for understanding Ordovician life in this part of the United States.