Ctenoptychius

Ctenoptychius (meaning "comb-folded", from the Greek κτείς or kteís meaning "comb" and πτυχή or ptychos meaning "fold") is an extinct genus of cartilaginous fish in the order Petalodontiformes. While Ctenoptychius was historically thought to encompass a large number of species with serrated tooth crowns, it is now considered to include only the type species, C. apicalis. This species lived during the Late Carboniferous period, and its fossils are known from the United Kingdom and potentially the United States. C. apicalis is known primarily from teeth, which have a flattened shape and serrated edges, although poorly-preserved specimens preserving the head, pectoral fins and scales of the body are also known. Based on this, it is believed that Ctenoptychius had a flattened, ray-like body.