Ctenacanthiformes

Ctenacanthiformes is an extinct order of cartilaginous fish. They possessed ornamented fin spines at the front of their dorsal fins and cladodont-type dentition, that is typically of a grasping morphology, though some taxa developed cutting and gouging tooth morphologies. Some ctenacanths are thought to have reached sizes comparable to the great white shark, with body lengths of up to and weights of , while others reached lengths of only . The earliest ctenacanths appeared during the Frasnian stage of the Late Devonian (~383-372 million years ago), with the group reaching their greatest divers

Glikmanius is an extinct genus of ctenacanth cartilaginous fish which lived in the Carboniferous of North America and Russia. Skeletal remains attributed to the genus are known from Nebraska, USA. Glikmanius is named in honour of the Russian palaeontologist, Dr. Leonid Glikman, who studied the genus and was "the first to propose its ctenacanthiform affinity". G. careforum may have reached lengths of , while G. occidentalis may have reached lengths of over , making it one the largest marine predators of its time. left|thumb|Tooth of Glikmanius occidentalis. ==References==

thumb|Front portion of the body of Ctenacanthus concinnus (originally described as "C. clarkii") from the Devonian-age [[Cleveland Shale]] Ctenacanthus (from , 'comb' and , 'spine') is an extinct genus of ctenacanthiform chondrichthyan. Remains have been found in the Bloyd Formation (Carboniferous Period) of Arkansas and the Cleveland Shale (Devonian Period) of Ohio in the United States and in South America.

Dracopristis (meaning 'dragon shark') is an extinct genus of ctenacanth (a group of shark-like cartilaginous fish) that lived during the Carboniferous period in North America, around 307 million years ago. The species was discovered in the Kinney Brick Quarry in New Mexico, USA. Like many fossils from the site, the fossils of Dracopristis are very well-preserved. A single species is known, Dracopristis hoffmanorum, which is named in honor of Ralph and Jeanette Hoffman, the owners of the quarry. Prior to being scientific named, D. hoffmanorum was informally referred to as the "Godzilla shark".

Goodrichthys is a Carboniferous genus of ctenacanthiform from the Glencartholm Volcanic Beds Formation (Upper Border Group) of Scotland.