 The majority of teleost species belong to the clade Euteleostei ; which consists of 17 @,@ 419 species classified in 2935 genera and 346 families . Shared traits of the euteleosts include ; similarities in the embryonic development of the bony or cartilaginous structures located between the head and dorsal fin ( supraneural bones ) , an outgrowth on the stegural bone ( a bone located near the neural arches of the tail ) and caudal median cartilages located between hypurals of the caudal base . The two major groups of euteleosts are Protacanthopterygii , which consists of fish like salmon , pike and smelts and Neoteleosti which contain the majority of euteleosts . A derived trait of neoteleosts is a muscle that controls the pharyngeal jaws , giving them a role in grinding food . Within neoteleosts , the Acanthopterygii have a spiny dorsal fin which is in front of the soft @-@ rayed dorsal fin . This fin helps provide thrust in locomotion and may also play a role in defense . Acanthomorphs have developed spiny ctenoid scales ( as opposed to the cycloid scales of other groups ) , tooth @-@ bearing premaxilla and greater adaptations to high speed swimming . 
