Although a diverse, invertebrate fauna is characteristic of the Upper Devonian, Lime Creek Formation, in north central Iowa, fossil fish remains are sparse. A detached and incomplete shark spine with ctenacanthoid features is reported and described. The specimen is the best example of the first occurrences of its kind from Devonian of Iowa. Despite some asymmetry in shape, the spine is interpreted as the cutwater of a dorsal fin. Overall length of the shark is estimated at l-l.5m
