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.
Neopterygii 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 fishes, and over half of all living vertebrate species. While living holosteans include only freshwater taxa, teleosts are diverse in both freshwater and marine environments. Many new species of teleosts are scientifically described each year.
Pholidophorus is an extinct genus of stem-teleost fish. Numerous species were assigned to this genus in the past, but only the type species Pholidophorus latiusculus, from the Late Triassic of Europe, is considered to be a valid member of the genus today.
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 Nevada, United States. The oldest fossils are from Griesbachian aged beds of the Wordie Creek Formation of East Greenland.
Pachycormus is an extinct genus of pachycormiform ray-finned fish known from the Early Jurassic of Europe. The type species P. macropterus was first named as a species of Elops by Henri Marie Ducrotay de Blainville in 1818, it was placed into the newly named genus Pachycormus by Louis Agassiz in 1833. Fossils have been found in marine deposits from France, Germany and England. Pachycormus has recently been considered monotypic, only containing P.macropterus, with other species considered junior synonyms of the former, though this has subsequently been questioned. Pachycormus has generally been considered basal among Pachycormiformes, with a recent phylogeny finding it to be the second most basal pachycormiform after Euthynotus. It grew up to 1 m (3.5 ft) in length. The teeth are short and designed for grasping. Its ecology has been interpreted as that of a generalist predator.
Pteronisculus is an extinct genus of prehistoric ray-finned fish that lived during the Early Triassic and Middle Triassic epochs of the Triassic period worldwide.
Acrolepis is an extinct genus of prehistoric marine bony fish that lived from the Tournaisian stage of the Mississippian to the late Permian epoch. Some species from the Early Triassic of Tasmania are also ascribed to Acrolepis.
Styracopterus is an extinct genus of prehistoric bony fish that lived during the Tournaisian stage of the Mississippian epoch of Scotland and Eastern European Platform, Russia.
Euthynotus is an extinct genus of prehistoric bony fish that lived during the early Toarcian stage of the Early Jurassic epoch. It is generally considered the basalmost pachycormiform.
Cyranorhis is an extinct genus of prehistoric bony fish that lived during the Serpukhovian age of the Carboniferous period in what is now Montana, United States.
Dialipina is an extinct genus of prehistoric, marine osteichthyan. It was initially thought to be an early, basal actinopterygian, but recent phylogenetic analyses suggest that it may instead be a stem-osteichthyan.
Strepheoschema is an extinct genus of prehistoric bony fish that lived during the early Mississippian (Tournaisian–Visean) in what is now Berwickshire, Scotland, and Northumberland, England. Fossils were recovered from the Ballagan Formation.
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.
Ichthyokentema ("fish-goad") is an extinct genus of stem-teleost fish that lived during the Late Jurassic. It contains one species, I. purbeckensis, which is known from the Purbeck Group of Dorset, England. I. purbeckensis was originally described as a species of Pholidophorus by William Davies in 1887, but was moved to its own genus by Arthur Smith Woodward in 1941.
Igornella is an extinct genus of prehistoric bony fish that lived during the Gzhelian (Stephanian) to Asselian ages in what is now France (Burgundy).
Saurorhynchus is an extinct genus of carnivorous bony fish that lived during the Early and Middle Jurassic epochs. Fossils have been found in Europe and North America (Canada). It is commonly found in pelagic and lagoonal deposits, but mostly marine. Largest specimens can grow up to 1.9 metres (6.2 ft).
Phanerosteon is an extinct genus of prehistoric bony fish from the Carboniferous period. The type species, P. mirabile, was recovered from the Calciferous sandstone series (Pennsylvanian), Scotland. A second species, P. phonax was described from the Serpukhovian aged Bear Gulch Limestone lagerstätte in Montana, United States.
Archaeomaenidae is an extinct family of stem-teleost fish found in freshwater environments of Jurassic New South Wales of Australia, China, and Antarctica, and in Lower Cretaceous New South Wales and Mongolia.
Ohmdenia is an extinct genus of prehistoric bony fish that lived from the Toarcian stage of the Early Jurassic period. Ohmdenia was first described in 1953 by Bernhard Hauff, based on a fossil found in the well-known Posidonia Shale in Holzmaden, Germany. For a long time this animal has been considered a close relative of Birgeria, a great predator typical of the Triassic period with an uncertain systematic position. Further studies have shown similarities with the Pachycormiformes, a group considered close to the origin of teleosts and also including giant forms and planktives. Some studies have erroneously indicated Ohmdenia as a synonym of Saurostomus, other studies have instead placed Ohmdenia as an important evolutionary passage between the basal pachicormiforms and the more derived planktivore pachicormiformes.
Dorsetichthys is an extinct genus of stem-teleost ray-finned fish from the Early Jurassic period of Europe.
