Chondrichthyes is a class of jawed fish that contains the cartilaginous fish or chondrichthyians, which all have skeletons primarily composed of cartilage. They can be contrasted with the Osteichthyes or bony fish, which have skeletons primarily composed of bone tissue. Chondrichthyes are aquatic vertebrates with paired fins, paired nares, placoid scales, conus arteriosus in the heart, and a lack of opecula and swim bladders. Within the infraphylum Gnathostomata, cartilaginous fishes are distinct from all other jawed vertebrates.
The Lamniformes are an order of sharks commonly known as mackerel sharks. It includes some of the most familiar species of sharks, such as the great white, as well as more unusual representatives, such as the goblin shark and megamouth shark.
Elasmobranchii is a subclass of Chondrichthyes or cartilaginous fish, including modern sharks, rays, skates, and sawfish. Members of this subclass are characterised by having five to seven pairs of gill clefts opening individually to the exterior, rigid dorsal fins and small placoid scales on the skin. The teeth are in several series; the upper jaw is not fused to the cranium, and the lower jaw is articulated with the upper. The details of this jaw anatomy vary between species, and help distinguish the different elasmobranch clades. The pelvic fins in males are modified to create claspers for the transfer of sperm. There is no swim bladder; instead, these fish maintain buoyancy with large livers rich in oil.
The Dalatiidae are the family of kitefin sharks of the order Squaliformes. Members of this family are small, under 2 m (6.6 ft) long, and are found worldwide. They have cigar-shaped bodies with narrow heads and rounded snouts. Several species have specialized bioluminescent organs. Though eight genera are in this family, four of them are monotypic.
Rajiformes is one of the four orders in the superorder Batoidea, flattened cartilaginous fishes related to sharks. Rajiforms are distinguished by the presence of greatly enlarged pectoral fins, which reach as far forward as the sides of the head, with a generally flattened body. The undulatory pectoral fin motion diagnostic to this taxon is known as rajiform locomotion. The eyes and spiracles are located on the upper surface of the head and the gill slits are on the underside of the body. Most species give birth to live young, although some lay eggs enclosed in a horny capsule.
Hybodus is an extinct genus of hybodont, a group of shark-like euselachians that lived from the Late Devonian to the end of the Cretaceous. Species closely related to the type species Hybodus reticulatus lived during the Early Jurassic epoch. 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.
Hybodontiformes, commonly called hybodonts, are an extinct group of shark-like cartilaginous fish (chondrichthyans) which existed from the late Devonian to the Late Cretaceous. Hybodonts share a close common ancestry with modern sharks and rays (Neoselachii) as part of the clade Euselachii. They are distinguished from other chondrichthyans by their distinctive fin spines and cephalic spines present on the heads of males. An ecologically diverse group, they were abundant in marine and freshwater environments during the late Paleozoic and early Mesozoic, but were rare in open marine environments by the end of the Jurassic, having been largely replaced by modern sharks, though they were still common in freshwater and marginal marine habitats. They survived until the end of the Cretaceous, before going extinct.
Pristiophorus is a genus of sawsharks found in the Pacific, Atlantic and Indian oceans. Members of this genus differ from the Sixgill Sawshark (Pliotrema warreni) in having five gill slits. Their rostral sawteeth lack prominent transverse ridges on the basal ledges, and the large teeth are not posteriorly serrated.
Lonchidion is a genus of extinct hybodont shark in the family Lonchidiidae. The genus first appears in the fossil record during the Middle Triassic (Ladinian) and was among the last surviving hybodont genera, with its youngest known fossils dating to the very end of the Cretaceous (Maastrichtian).
Gladioserratus is an extinct genus of cow shark. It contains three species:
Dwardius is an extinct genus of cardabiodontid sharks which existed during the Cretaceous period in what is now Australia, England, France, and India. It was described by Mikael Siverson in 1999, as a new genus for the species Cretalamna woodwardi, which had been described by J. Hermann in 1977. Another species, D. siversoni, was described from the middle Albian of northeastern France by V.I. Zhelezko in 2000; the species epithet honours the author of the genus. A new species, D. sudindicus, was described by Charlie J. Underwood, Anjali Goswami, G.V.R. Prasad, Omkar Verma, and John J. Flynn in 2011, from the Cretaceous Karai Formation of India.
Eosqualiolus is an extinct genus of sharks in the family Dalatiidae. It was described by Sylvain Adnet in 2006, and the type species is E. aturensis, which existed during the middle Eocene of what is now France. A new species, E. skrovinai, which existed in what is now Slovakia during the Miocene period, was described by Charlie J. Underwood and Jan Schlogl in 2012, and named in honour of Michal Škrovina. E. skrovinai was described from 14 fossil teeth found in the Laksarska Nova Ves Formation; 9 upper and 5 lower, some of which were partial and some were complete.
Nanocetorhinus is an extinct genus of sharks in the subclass Neoselachii. The type and only described species is N. tuberculatus, which existed in what is now Slovakia during the Miocene epoch, and was described by Charlie J. Underwood and Jan Schlogl in 2011. It was described from 28 fossilized teeth.
Pristiophorus striatus is an extinct species of sawshark in the genus Pristiophorus. It existed in what is now Slovakia during the Miocene epoch, and was described by Charlie J. Underwood and Jan Schlogl in 2012.
Cretorectolobus is an extinct carpet shark. It was described by G.R. Case in 1978, and the type species is C. olsoni, which existed during the Campanian in Canada and the United States. Another species, C. gracilis, was described by Charlie J. Underwood and Mitchell in 1999, from the Hauterivian to Barremian strata of the Speeton Clay Formation of England. The species epithet refers to the shark's teeth, which Underwood and Mitchell described as gracile and narrow in form. A new species, C. robustus, was described from the Cenomanian of Canada by Underwood and Stephen L. Cumbaa in 2010.
Roulletia is an extinct genus of sand sharks. It was described by Romain Vullo, Henri Cappetta, and Didier Néraudeau in 2007, and the type species is R. bureaui, which existed during the upper Cenomanian of what is now France. The genus was named after its type locality, Roullet-Saint-Estèphe, while the species epithet honours Michel Bureau, an amateur paleontologist who gathered the material for the species. Another species, R. canadensis, was described from the Cenomanian of Canada by Charlie J. Underwood and Stephen L. Cumbaa in 2010. The species epithet refers to the country in which it was discovered. It has been suggested tentatively this genus may be related to Haimirichia, which has been placed in its own family (Haimirichiidae) based on soft-tissue preservation.
This list of fossil fishes described in 2013 is a list of new taxa of placoderms, fossil cartilaginous fishes and bony fishess of every kind that have been described during the year 2013. The list only includes taxa at the level of genus or species.
Paleotriakis is a genus of ground sharks that lived in the Late Cretaceous period of France.
This list of fossil fishes described in 2019 is a list of new taxa of jawless vertebrates, placoderms, acanthodians, fossil cartilaginous fishes, bony fishes, and other fishes of every kind that were described during the year 2019, as well as other significant discoveries and events related to paleoichthyology that occurred in 2019.
Parvodus is an extinct genus of hybodont, known from the Mesozoic era.
