Gnathostomata
1. A superclass of jawed vertebrates that includes the fishes, Amphibia, Reptilia, Aves, and Mammalia. Recently it has been proposed that Gnathostomata should comprise the Elasmobranchii (sharks, rays, etc.) and the Teleostomi (i.e. Osteichthyes and Sarcopterygii). In this classification Pisces becomes redundant.

2. (phylum Echinodermata, class Echinoidea) A superorder of echinoids in which the periproct is outside the apical system, there are no compound ambulacral plates, an Aristotle's lantern and girdle are present, and the teeth are keeled. It includes the orders Holectypoida and Clypeasteroida.

Gnathostomata
1. Superclass comprising all vertebrates with true jaws.

2. (phylum Echinodermata, class Echinoidea) Superorder of echinoids, in which the periproct is outside the apical system, there are no compound ambulacral plates, a lantern (see ARISTOTLE'S LANTERN) and girdle are present, and the teeth are keeled. It includes the orders Holectypoida (Jurassic–Recent), and Clypeasteroida (sand dollars, Palaeocene—Recent).

Gnathostomata A subphylum or superclass of chordates consisting of all vertebrates that possess jaws. It contains six extant classes: Chondrichthyes (cartilaginous fishes), Osteichthyes (bony fishes), Amphibia, Reptilia, Aves (birds), and Mammalia. Compare Agnatha.