From Ohio History Central
Trace fossils (ichnofossils) consist of burrows, trails, track borings, and footprints found in marine and nonmarine rocks. Although the remains of the animal that made the particular trace fossil may not be present, they preserve a record of inorganic activity. Trace fossils are found in all of Ohio’s geologic systems and are very abundant in some rock units. Many burrows were probably made by soft-bodied marine worms that fed on organic detritus in the sediment. Bedding planes in some rocks have plant-like impressions that represent feeding activities by marine worms that probably swept the nearby sea floor with feeding structures. Tracks of trilobites have been identified. Non-marine rocks of Pennsylvanian age in eastern Ohio have yielded footprints of amphibians.
- Hannibal, J. T., 1996. "Ichnofossils," in Fossils of Ohio, edited by R. M. Feldmann and Merrianne Hackathorn. Ohio Division of Geological Survey Bulletin 70, p. 506-529.