Holostei- a superorder of fishes of the subclass Actinopterygii of the class Osteichthyes. The axial skeleton is completely ossified. The jaw arch is attached to the skull by means of the hyomandibularis (amphistylium). The body is covered with bony or ganoid scales. The swim bladder is two-chambered, cellular, and performs respiratory functions. There is a spiral valve in the intestine and an arterial cone in the heart. All modern fishes are grouped into two orders: Amiiformes and Lepisosteiformes.
An infraclass of ray-finned fishes with a number of primitive features. Occupy an intermediate position between cartilaginous ganoids and bony fishes. The skull, jaw and gill apparatus has the same structure as in bony fishes. The caudal fin is constructed according to the type of cartilaginous ganoids (heterocercal). The scales are ganoid. Bony ganoids are known from the Late Permian. In the Mesozoic, bony ganoids numbered 7 orders, before the beginning of the Paleogene, almost all of them became extinct.