Actinopterygii, members of which are known as ray-finned fish or actinopterygians, is a class of bony fish that comprise over 50% of living vertebrate species. They are so called because of their lightly built fins made of webbings of skin supported by radially extended thin bony spines called lepidotrichia, as opposed to the bulkier, fleshy lobed fins of the sister class Sarcopterygii. Resembling folding fans, the actinopterygian fins can easily change shape and wetted area, providing superior thrust-to-weight ratios per movement compared to sarcopterygian and chondrichthyian fins. The fin rays attach directly to the proximal or basal skeletal elements, the radials, which represent the articulation between these fins and the internal skeleton.
Bichirs and the reedfish comprise Polypteridae, a family of archaic ray-finned fishes and the only family in the order Polypteriformes.
Euteleostomi is a successful clade that includes more than 90% of the living species of vertebrates. Both its major subgroups are successful today: Actinopterygii includes most extant bony fish species, and Sarcopterygii includes the tetrapods.
Polypterus is a genus of freshwater fish in the bichir family (Polypteridae) of order Polypteriformes. The type species is the Nile bichir. Fish in this genus live in various areas in Africa. Polypterus is the only known vertebrate to have lungs, but no trachea.
The Palaeonisciformes, commonly known as "palaeoniscoids" are an extinct grouping of primitive ray-finned fish (Actinopterygii), spanning from the Silurian/Devonian to the Cretaceous. They are generally considered paraphyletic, but their exact relationships to living ray-finned fish are uncertain. While some and perhaps most palaeoniscoids likely belong to the stem-group of Actinopteryii, it has been suggested that some may belong to the crown group, with some of these possibly related to Cladistia and/or Chondrostei. Many palaeoniscoids share a conservative body shape and a similar arrangement of skull bones.
Birgeria is a genus of carnivorous marine ray-finned fish from the Triassic period. Birgeria had a global distribution, with fossil known from Madagascar, Spitsbergen, Germany, Switzerland, Italy, Slovenia, China, Russia, Canada and Nevada, United States. The oldest fossils are from Griesbachian aged beds of the Wordie Creek Formation of East Greenland. Birgeria existed throughout the entire Triassic period, from the very beginning just after the Permian-Triassic mass extinction, up to the very end with its extinction during the Triassic-Jurassic mass extinction.
The barred bichir, armoured bichir, bandback bichir, or banded bichir is a species of fish belonging to the class Actinopterygii, or the ray-finned fish, which constitute an order of the class of the bony fish. an elongated fish found in the Congo River, specifically in the upper and middle portions. This species is one of the more commonly available in commercial pet stores.
Scanilepis is an extinct genus of prehistoric bony fish that lived during the Rhaetian-?Hettangian ages. The type species, S. dubia, is known from the Rhaetian freshwater deposits of the Bjuv member of the Höganäs Formation, southwestern Sweden. A second species, S. spitzbergensis was mentioned from the Hettangian of the Festning section of the Grøfjorden area in Spitsbergen, Norway but was never described.
Boreolepis is an extinct genus of prehistoric marine ray-finned fish that lived from the Late Kungurian to the Wuchiapingian of the Permian period. It inhabited the high northern latitudes in what is now Greenland and European Russia.
Boreosomus is an extinct genus of Triassic marine ray-finned fish. It was first described from the Arctic island of Spitsbergen, hence its genus name, but was later also discovered in other parts of the world. The type species is Boreosomus arcticus.
Prohalecites is an extinct genus of ray-finned fish from the Ladinian and possibly Carnian (Triassic) of Italy. It is the oldest known teleosteomorph, a group that includes extant teleosts and their close fossil relatives.
Saurichthyiformes is an extinct order of ray-finned fish which existed in Asia, Africa, Australia, Europe and North America, during the late Permian to early Middle Jurassic. Saurichthyiiformes comprise two families, Saurichthyidae and Yelangichthyidae. Yelangichthyidae is monotypic, containing only the genus Yelangichthys. The gar or needlefish-like Saurichthyidae is primarily known from the genus Saurichthys. Additionally, the subgenera SaurorhynchusCostasaurichthys, Eosaurichthys, Lepidosaurichthys, and Sinosaurichthys are frequently used to group species, and are sometimes considered separate genera. Species are known from both marine end freshwater deposits. They had their highest diversity during the Early and Middle Triassic. Their phylogenetic position is uncertain, while they have often been considered members of Chondrostei, and thus related to living sturgeons and paddlefish, phylogenetic analysis of well-preserved remains has considered this relationship equivocal. They may actually belong to the stem-group of Actinopterygii, and thus not closely related to any living group of ray-finned fish.
Beishanichthys is an extinct genus of freshwater ray-finned fish which existed in Gansu Province, China during the Olenekian age of the early Triassic period. It contains a single species, B. brevicaudalis, first named by Guang-Hui Xu, Ke-Qin Gao in 2011 based on fossils from the Lower Triassic lake deposits exposed in Beishan area. It is considered a scanilepiform, a group of early cladistians related to the modern bichirs, although Beishanichthys was not incorporated into the analyses that found this phylogenetic placement among the cladistians.
Polypterus palmas, also called the shortfin or marbled bichir, is a fish in the family Polypteridae found in freshwater environments throughout West Africa.
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.
Polypterus mokelembembe is a species of the fish genus Polypterus, found in the central basin of the Congo River. It was once considered a morph of the closely related Polypterus retropinnis, but was given species status in 2006 with a description that reclassified both fishes. Because of the recency of the species' description and the fact that P. mokelembembe is the paralectotype of P. retropinnis, they are often mistaken for one another in the aquarium trade.
Polypterus polli, Poll's bichir, is a species of bichir from the Malebo Pool and the lower and central basins of the Congo River. It was named in honor of Belgian ichthyologist Max Poll.
Parasemionotiformes is an extinct order of neopterygian ray-finned fish that existed globally during the Triassic period. It comprises the families Parasemionotidae and Promecosominidae. Many of the included genera are monotypic and most species lived during the Early Triassic epoch.
Serenoichthys is an extinct genus of small bichir from the Late Cretaceous (Cenomanian) of southeastern Morocco. The genus is monotypic, the type and only species being Serenoichthys kemkemensis. Only known at first from postcranial skeletons, complete specimens were later discovered.
Acropholis is an extinct genus of prehistoric marine bony fish that lived during the Wuchiapingian age in what is now Greenland and Hesse (Germany).
