Boschung, Herbert T. Formerly, Department of Biological Sciences, University of Alabama, Tuscaloosa, Alabama.
Bailey, Reeve M. Formerly, Division of Fishes, Museum of Zoology, University of Michigan, Ann Arbor, Michigan.
Last reviewed:July 2015
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- Family Acipenseridae (sturgeons)
- Family Polyodontidae (paddlefishes)
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An order of actinopterygian (ray-finned) fishes represented by the sturgeons and paddlefishes. The order Acipenseriformes, the only extant order of about 10–12 orders of chondrosteans (subclass Chondrostei), probably originated from palaeonisciform ancestors during the Triassic or Jurassic periods. Acipenseriform fishes are characterized by a largely cartilaginous skeleton, a heterocercal tail, fins with more than one ray per pterygiophore, a spiral valve intestine, a reduced or absent myodome, a reduced or absent preopercle, and an absent gular plate. The cartilaginous skeleton of the members of the Acipenseriformes, long regarded as primitive, was taken as indicative of an alliance with the Chondrichthyes (cartilaginous fishes); however, cartilage is secondary and the true relationship is with the Osteichthyes (bony fishes). See also: Actinopterygii; Osteichthyes; Palaeonisciformes
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