A class of teleostom fishes commonly known as the ray-finned fishes comprising the subclasses Cladistia (Polypteriformes and fossil orders), Chondrostei (Acipenseriformes and fossil orders), and Neopterygii (the remaining actinopterygian orders). The Neopterygii, minus the Lepisosteiformes, Amiiformes, and several fossil taxa, comprise the Teleostei (see illustration). The Actinopterygii comprise about half of all vertebrate species and about 96% of all currently existing fishes. It is considered a nonmonophyletic group that is derived from more than one lineage when tetrapods are excluded. The Actinopterygii and the Sarcopterygii, minus the Tetrapoda, comprise what was previously called Osteichthyes (the bony fishes). The class includes 44 orders, 453 families, 4289 genera, and about 27,000 described extant species. Many species are known to science but are not yet described; further, in regions such as the Amazon and Congo basins, species are probably becoming extinct before they are discovered and described in the scientific literature.