Group of marine and freshwater bony fish including many fossil species, e.g. Lepidotes (Triassic–Cretaceous), and Dapedius (Jurassic). Holosteans arose at the end of the Permian from palaeoniscid ancestors and are particularly abundant in marine Jurassic deposits. The main characteristics shown by the group relate to improvements in swimming and feeding: the use of the air sac to control buoyancy; a reduction in the bony fin rays, now unjointed; the development of a shorter and more mobile jaw; the gradual reduction in scale thickness; and the development of an almost symmetrical tail. Holosteans are represented today only by the garpike (Lepisosteus), and the bowfin (Amia), both freshwater.