any member of the subclass, or infraclass, Chondrostei, a group of primitive, ray-finned bony fishes represented by the sturgeons and paddlefishes and many fossil species. They comprise one of the three major subdivisions of the class Actinopterygii, the other two being the holosteans and the teleosts. Fossilized chondrosteans first appear in rocks of the Middle Devonian Period (about 375,000,000 years ago). The only living representatives are the sturgeons and paddlefishes; the living bichirs (polypterids and the closely related reedfish) of Africa are also considered to be chondrosteans by some ichthyologists.
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