Chondrostei is a group of non-

neopterygian Neopterygii (from Greek νέος ''neos'' 'new' and πτέρυξ ''pteryx'' 'fin') is a subclass of ray-finned fish (Actinopterygii). Neopterygii includes the Holostei and the Teleostei, of which the latter comprise the vast majority of extant f ...

ray-finned fish Actinopterygii (; ), members of which are known as ray-finned fishes, is a class of bony fish. They comprise over 50% of living vertebrate species. The ray-finned fishes are so called because their fins are webs of skin supported by bony or h ...

, while the term originally referred to a

paraphyletic In taxonomy, a group is paraphyletic if it consists of the group's last common ancestor and most of its descendants, excluding a few monophyletic subgroups. The group is said to be paraphyletic ''with respect to'' the excluded subgroups. In ...

group of all non-neopterygian ray-finned fish, it was redefined by Patterson in 1982 to be a clade comprising the

Acipenseriformes Acipenseriformes is an order of basal ray-finned fishes that includes living and fossil sturgeons and paddlefishes (Acipenseroidei), as well as the extinct families Chondrosteidae and Peipiaosteidae. They are the second earliest diver ...

(which includes

sturgeon Sturgeon is the common name for the 27 species of fish belonging to the family Acipenseridae. The earliest sturgeon fossils date to the Late Cretaceous, and are descended from other, earlier acipenseriform fish, which date back to the Early ...

and

paddlefish Paddlefish (family Polyodontidae) are a family of ray-finned fish belonging to order Acipenseriformes, and one of two living groups of the order alongside sturgeons (Acipenseridae). They are distinguished from other fish by their titular elong ...

) and their extinct relatives. Taxa commonly suggested to represent relatives of the Acipenseriformes include the Triassic marine fish ''

Birgeria ''Birgeria'' is a genus of carnivorous marine ray-finned fish from the Triassic period. ''Birgeria'' had a global distribution. Fossils were found in Madagascar, Spitsbergen, Germany, Switzerland, Italy, Slovenia, China, Russia, Canada and Ne ...

'' and the Saurichthyiformes, but their the relationship with the Acipenseriformes has been strongly challenged on

cladistical Cladistics (; ) is an approach to biological classification in which organisms are categorized in groups (" clades") based on hypotheses of most recent common ancestry. The evidence for hypothesized relationships is typically shared derived cha ...

grounds.

Coccolepididae Coccolepididae is an extinct family of ray-finned fish, known from the Early Jurassic to Early Cretaceous, most of which were originally referred to the type genus '' Coccolepis.'' They had a widespread distribution, being found in North and S ...

, a group of small weakly ossified Jurassic and Cretaceous fish found in both marine and freshwater environments, have been suggested to be close relatives of the Acipenseriformes, however, this has never been subject to cladistical analysis.

Classification

Acipenseridae Sturgeon is the common name for the 27 species of fish belonging to the family Acipenseridae. The earliest sturgeon fossils date to the Late Cretaceous, and are descended from other, earlier acipenseriform fish, which date back to the Early ...

— sturgeons **

Polyodontidae Paddlefish (family Polyodontidae) are a family of ray-finned fish belonging to order Acipenseriformes, and one of two living groups of the order alongside sturgeons (Acipenseridae). They are distinguished from other fish by their titular elongl ...

— paddlefishes **

Chondrosteidae Chondrosteidae is a family of extinct marine actinopterygian fishes in the order Acipenseriformes. Three genera are known from the Early Jurassic of Europe, ''Chondrosteus'', '' Gyrosteus'', and ''Strongylosteus''. Included species were of la ...

(†) ** Errolichthyidae(†) * Cheirolepidiformes(†) *

(†) *

Guildayichthyiformes Guildayichthyidae is a prehistoric family of marine fish from the Mississippian Bear Gulch Limestone of Montana. It is the only family in the order Guildayichthyiformes. Guildayichthyids possess an uncommon mixture of primitive and modern chara ...

(†) *

Luganoiiformes ''Luganoia'' is an extinct genus of prehistoric bony fish that lived during the early Ladinian stage of the Middle Triassic epoch. See also * Prehistoric fish * List of prehistoric bony fish A ''list'' is any set of items in a row. List or lis ...

(†) *

Palaeonisciformes The Palaeonisciformes (Palaeoniscida) are an extinct order of early ray-finned fishes (Actinopterygii). Palaeonisciformes ''sensu lato'' first appeared in the fossil record in the Late Silurian and last appeared in the Late Cretaceous. The name ...

(†) **

Acrolepidae Acrolepididae is an extinct family of ray-finned fish. Genera referred to Acrolepididae existed from the Early Carboniferous period to the Early Triassic epoch. They were nektonic carnivores with a fusiform body. Acrolepididae may be closely re ...

(†) **

Birgeriidae ''Birgeria'' is a genus of carnivorous marine ray-finned fish from the Triassic period. ''Birgeria'' had a global distribution. Fossils were found in Madagascar, Spitsbergen, Germany, Switzerland, Italy, Slovenia, China, Russia, Canada and N ...

(†) **

Palaeoniscidae Palaeoniscidae is an extinct family (biology), family of ray-finned fishes (Actinopterygii) ascribed to the order (biology), order Palaeonisciformes. The family includes the genus ''Palaeoniscum'' and potentially other Palaeozoic and Mesozoic ear ...

(†) *

Perleidiformes Perleidiformes are an extinct order of prehistoric ray-finned fish from the Triassic period Although numerous Triassic taxa have been referred to Perleidiformes, which ones should be included for it to form a monophyletic group is a matter of on ...

(†) * Phanerorhynchiformes(†) *

Pholidopleuriformes Pholidopleuriformes is an extinct order of ray-finned fish. Classification ** Family †Pholidopleuridae Abel 1919/Wade 1932 *** Genus †'' Gracilignathichthys'' Bürgin 1992 **** †'' Gracilignathichthys microlepis'' Bürgin 1992 *** Genus � ...

(†) *Polypteriformes **

Polypteridae Bichirs and the reedfish comprise Polypteridae , a family of archaic ray-finned fishes and the only family in the order Polypteriformes .Helfman GS, Collette BB, Facey DE, Bowen BW. 2009. The Diversity of Fishes. West Sussex, UK: Blackwell Pu ...

- bichirs and reedfish * Ptycholepiformes(†) * Saurichthyiformes(†) *

Tarrasiiformes Tarasiiformes is an extinct order of prehistoric ray-finned fish. Taxonomy * Order †Tarrasiiformes sensu Lund & Poplin 2002 aplistiaref name="mikko"> ** Family †Tarrasiidae Traquair 1881 emend. Woodward 1891 *** Genus †'' Apholidotos'' ...

(†)

References

{{Taxonbar, from=Q275646 Extant Silurian first appearances Paraphyletic groups