Boschung, Herbert T. Formerly, Department of Biological Sciences, University of Alabama, Tuscaloosa, Alabama.
Grande, Lance Field Musuem of National History, Chicago, Illinois.
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A class of teleostom fishes commonly known as the ray-finned fishes, which are distinguished by the structure of the paired fins that are supported by dermal rays. The class Actinopterygii comprises the subclasses Cladistia [Polypteriformes (bichirs and reedfishes) and fossil orders], Chondrostei [Acipenseriformes (sturgeons and paddlefishes) and fossil orders], and Neopterygii (the remaining actinopterygian orders) [Fig. 1]; however, it should be noted that some recent taxonomies now place the cladistians within the chondrosteans. The members of the Neopterygii, minus the Holostei [consisting of members of the Lepisosteiformes (gars), Amiiformes (bowfins), and several fossil taxa], comprise the Teleostei. Overall, the members of the Actinopterygii make up about half of all vertebrate species and approximately 96% of all currently existing fishes. Collectively, the class Actinopterygii is considered to be a nonmonophyletic group that is derived from more than one lineage when tetrapods are excluded. The Actinopterygii and the Sarcopterygii, minus the Tetrapoda, comprise the Osteichthyes (the bony fishes). The Actinopterygii includes more than 40 orders, about 430–480 families, more than 4000 genera, and about 27,000 described extant species. Many species are known to science, but are not yet described; furthermore, in regions such as the Amazon and Congo basins, species are probably becoming extinct before they are discovered and described in the scientific literature. See also: Acipenseriformes; Amiiformes; Holostei; Lepisosteiformes; Ostariophysi; Osteichthyes; Polypteriformes; Sarcopterygii; Teleostei; Teleostomi; Tetrapoda
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