Prehistoric cartilaginous fish genera

Helicoprion is an extinct genus of large shark-like cartilaginous fish that lived from the Early to the Middle Permian, about 290-270 million years ago. Helicoprion is a member of the Eugeneodontiformes, an extinct order of cartilaginous fish within the clade Holocephali, a group today represented only by chimaeras. It is also the type genus of the Helicoprionidae, a family of eugeneodonts characterised by distinctive tooth structures called tooth whorls. Helicoprion was first named in 1899 by Alexander Karpinsky on the basis of fossils discovered in Russia and Australia, the generic name mean

Hybodus (from , 'crooked' and 'tooth') is an extinct genus of hybodont. Numerous species have been assigned to Hybodus spanning a large period of time, and it is currently considered a wastebasket taxon that is 'broadly polyphyletic' and requires reexamination. It has been suggested that Hybodus sensu stricto only consists of two species, the type species H. reticulatus and H. hauffianus, both known from the Early Jurassic of Europe, with H. obtusus from the Middle-Late Jurassic of Europe possibly also being a true species of Hybodus.

Climatius (from , 'gradation') is an extinct genus of spiny shark. This genus is known from the Early Devonian (Lochkovian) of Europe, previously considered Silurian remains actually belong to Nostolepis instead.

Onchopristis is an extinct genus of sclerorhynchoid, or sawskate, from the Cretaceous of North Africa, Europe, North America, and potentially South America. The genus contains two valid species, O. numida and O. dunklei, though some researchers argue that both may be considered a single taxon with variation in morphology caused by a wide geographical range. Specimens of Onchopristis have been discovered in coastal and fluvial deposits dated from the Barremian to the Cenomanian ages (~125-94 mya), making this genus one of the oldest known sclerorhynchoids.

Xenacanthus (from Ancient Greek ξένος, xénos, 'foreign, alien' + ἄκανθος, akanthos, 'spine') is an extinct genus of xenacanth cartilaginous fish. It lived in freshwater environments, and fossils of various species have been found worldwide.

Orthacanthus is an extinct genus of fresh-water xenacanthiform cartilaginous fish, named by Louis Agassiz in 1843, ranging from the Upper Carboniferous into the Lower Permian. Orthacanthus had a nektobenthic life habitat, with a carnivorous diet. Multiple authors have also discovered evidence of cannibalism in the diet of Orthacanthus and of "filial cannibalism" where adult Orthacanthus preyed upon juvenile Orthacanthus. Synonyms of the genus Orthacanthus are Dittodus Owen, 1867, Didymodus Cope, 1883, Diplodus Agassiz, 1843, Chilodus Giebel, 1848 (preoccupied by Chilodus Müller & Troschel, 184

Edestus is an extinct genus of eugeneodontid holocephalian fish known from the Late Carboniferous (Pennsylvanian) of the United Kingdom, Russia, and the United States. Most remains consist of isolated curved blades or "whorls" that are studded with teeth, that in life were situated within the midline of the upper and lower jaws. Edestus is a Greek name derived from the word edeste (to devour), in reference to the aberrant quality and size of the species' teeth.

Fadenia is an extinct genus of eugeneodontid holocephalian chondrichthyan from the Carboniferous Period of Missouri (United States), the Permian period of Greenland, and the Early Triassic epoch of British Columbia, Canada (Sulphur Mountain Formation).

Parahelicoprion is an extinct genus of shark-like cartilaginous fish that lived during the Early Permian. The genus contains two species: P. clerci from the Arta Beds of the Ural Mountains of Russia, and P. mariosuarezi from the Copacabana Formation of Bolivia. Members of the genus possessed a row of large tooth crowns on the midline of the lower jaw, known as a tooth whorl. The characteristics of this whorl are unique to fishes of the order Eugeneodontida, and more specifically the family Helicoprionidae to which Parahelicoprion belongs. The genus name refers to Helicoprion, another eugeneodo

Listracanthus is a genus of extinct chondrichthyan with uncertain affinities. Species of Listracanthus are known primarily from their tremendous, feather-like denticles, which range up to four inches in length. The denticles had a large main spine, from which secondary spines emanate from the sides, like the barbs of a feather or a comb. Listracanthus first appeared in late Carboniferous strata in North America, and eventually disappear from the fossil record some time during the Early Triassic.

Ischyodus (from , 'power' and 'tooth') is an extinct genus of chimaera. It is the most diverse and long-lived chimaera genus, with over 39 species found worldwide spanning over 140 million years from the Middle Jurassic to the Miocene. Almost all species are only known from tooth plates, with the exception of the Jurassic species I. quenstedti. Complete specimens of I. quenstedti from the Late Jurassic of Germany most closely resemble the genus Callorhinchus amongst living chimaera genera. It is sometimes placed in the "Edaphodontidae", a unclearly defined group of chimaera with an uncertain p

Lissodus is an extinct genus of hybodont. While fossils attributed to this genus are known spanning from the latest Devonian (Famennian) to the very end of the Cretaceous (Maastrichtian), others consider the genus to have a more narrow range, spanning from the Early Triassic to the end of the Early Cretaceous (Albian). Lissodus is often placed in the family Lonchidiidae, though other authors consider it incertae sedis within Hybodontiformes. Lonchidion has often been regarded as synonymous, but many recent authors consider it to be a distinct but closely related genus. Some authors have propos

Asteracanthus (from , 'star' and , 'spine') is an extinct genus of hybodont, known from the Middle Jurassic (Bathonian) to the Early Cretaceous (Valanginian).

thumb|left|Restoration of T. sesselensis

thumb|left|Teeth of Janassa Janassa is an extinct genus of petalodont cartilaginous fish that lived in marine environments in what is now central United States of America and Europe during the Carboniferous and upper Permian.

Belantsea (named after a legendary ancestor of the Crow Tribe) is a genus of extinct petalodontiform cartilaginous fish that lived during the Early Carboniferous. Fossils of Belantsea montana have been found in the Bear Gulch Limestone lagerstätte, and are preserved in exceptional detail. Its body was tall and compressed, with large pectoral fins and a small tail fin. This body plan suggests a lifestyle similar to modern reef fish, and it is thought that Belantsea was adapted for life in reefs of sponges. Its few, large, triangular teeth suggest a diet of hard-shelled marine invertebrates. The

Caseodus is an extinct genus of eugeneodont from the Carboniferous of what is now the Midwestern United States, and potentially the Early Triassic of what is now British Columbia, Canada. The genus contains two Carboniferous species, C. basalis and C. eatoni, which are differentiated by the anatomy of their teeth but are otherwise identical. A third species, C. varidentis, is known from the Early Triassic Sulphur Mountain Formation, but due to its wildly different skull and tooth morphology it is questionable if it belongs in the genus. The genus name is in honor of paleoichthyologist Gerard C

Sphenacanthus (from , 'wedge' and , 'spine') is an extinct genus of a chondrichtyan xenacanthiform that belongs to the Sphenacanthidae family and lived from the Late Devonian, through Carboniferous until the Late Permian period in Scotland, Spain, Russia and Brazil. It lived 359 million years ago, and probably it was one of the first member of the elasmobranchians, the lineage that leads to the modern sharks. Sphenacanthus probably hunted small fishes and, unlike their modern-day relatives, it inhabited fresh water lagoons. Sphenacanthus had seven fins, two in the upper part and five in the un

Nostolepis is an extinct genus of acanthodian fish which lived from the Silurian (Wenlock) to the Middle Devonian (Givetian). Members of the genus include Nostolepis gracilis and Nostolepis striata.

Campodus is an extinct genus of eugeneodont holocephalans from the Carboniferous. Likely one of the earliest and most basal caseodontoids, it can be characterized by its broad, ridge-ornamented crushing teeth made of various types of dentine. The type species, C. agassizianus, was originally described in 1844 based on a small number of teeth from the Namurian of Belgium.

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.

Myledaphus is an extinct genus of guitarfish. It currently contains four valid species found in North America (M. bipartitus, M. pustulosus), South America (M. araucanus), and Central Asia (M. tritus). It is confirmed to have lived during the Late Cretaceous, with possible occurrences in the Paleocene and early Eocene. While the genus is mostly known from teeth, two partial skeletons of M. bipartitus have been found in the Dinosaur Park Formation of Alberta.

Micropristis is an extinct genus of ganopristid sclerorhynchoid that lived in the Middle East and Europe during the Late Cretaceous. The type specimen is known from the Cenomanian of Lebanon, and other specimens referrable to this genus have been found in Santonian-Campanian age rocks of Europe.

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".

Titanonarke is an extinct genus of large electric rays known from the Ypresian age of the Eocene epoch. It currently contains two species from the Bolca Lagerstatte of Italy, T. molini and T. megapterygia. The exceptional preservation of multiple entire individuals has allowed a detailed reconstruction of their lives. Specimens of both species have been found with various ontogenetic stages and with parasitic isopods preserved. One specimen contains a fossilized embryo, showing this species to be viviparous. This species seems to prefer shallow water habitats associated with coral reefs, not u

Doliodus is a genus of cartilaginous fish known from the Early Devonian period of what is now New Brunswick, Canada. It includes a single named species, either D. problematicus or D. latispinosus, which was originally described based on isolated teeth and potentially fin spines, but has since had a well-preserved body fossil assigned. The classification of the genus is uncertain, but it has been considered a member of the order Omalodontiformes. A more complete specimen that some authors assign to the genus shows features that are transitional between the extinct acanthodians and cartilaginous

left|thumb|Life reconstruction of Deltoptychius alongside the related Menaspiformes|menaspiform [[Menaspis]] Deltoptychius (from , 'triangle' and 'fold') is an extinct species of cartilaginous fish related to the modern chimaeras. It lived in the Carboniferous period in present-day United Kingdom. Fossils of the genus have been found in the Glencartholm Volcanic Beds Formation of the Upper Border Group in Scotland.

Echinochimaera ("prickly chimaera") is an extinct genus of chimaeriform fish, known from the Lower Carboniferous Bear Gulch Limestone in Montana, United States. It is one of the earliest Chimaeriformes known.

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

Spathobatis (from , 'blade' and 'ray') is an extinct genus of rays in the family Asterodermidae from the Jurassic period of Europe.

Meristodonoides is an extinct genus of hybodont known from the mid-late Cretaceous, with potential records dating back to the Jurassic. It is one of a number of hybodont genera composed of species formerly assigned to Hybodus.

left|thumb|212x212px|Life restoration of O. micropterygius

Squatinactis is a genus of extinct elasmobranch chondrichthyan known from the Carboniferous aged Bear Gulch Limestone in Montana. This fish was discovered in 1974 by Richard Lund. The type specimen, named CMNH 46133, consists of a brain case, poorly preserved jaws and gills, a pectoral fin, and a partial vertebral axis. This creature's most startling feature were its broad pectoral fins which resembled those of stingrays and angel sharks (Squatina). The holotype specimen has about 15 teeth in its jaw. This creature is named after the angel shark. Remains found in the South Urals of Russia and