Subphylum of the phylum Chordata. The Gnathostomata are jawed vertebrates. One pair of visceral arches modified as biting jaws; 2 nasal capsules or tubes; 3 pair of semicircular canals; usually with paired appendages (fins or limbs); sexes separate.
There are two super classes: Pisces (fishes) and Tetrapoda (four-legged "land" vertebrates).