<BGSOUND src="premaxilla.wav"> premaxilla

premaxilla

noun

One of the paired, superficial, usually toothed, dermal bones of the upper jaw, proximal or anterior to the maxillaries; in primitive Teleostomi they comprise the middle, in more advanced forms they may comprise the whole, of the oral edge of the upper jaw. Teeth may be present. In Diodontidae, the premaxillae are ankylosed and form a single bone. Absent in Chondrostei. In Holostei (Lepisoteus and Amia) the bone has two ossification centres and therefore is a double bone. Holostei and Teleostei have an ascending process anteriorly but these may not be homologous. Posterior to the ascending process in Teleostei there may be an articular and a postmaxillary process, and a posterior extension, the caudal process. Also called premaxillary, surmaxillary, bimaxillary or intermaxillary.