Supernumerary median fin-rays in teleostean fishes

Abstract

Supernumerary fin-rays in the dorsal and anal fins are those that articulate directly with the head of the first proximal radial; they lie in front of the ray serially associated with the first radial. The argument presented here is that just as the number of fin-rays per dorsal and anal radial has decreased in actinopterygian history, so the number of dorsal and anal supernumeraries has decreased in teleosts. It is proposed that D > 3 and A > 3 (more than three dorsal and anal supernumeraries) is the condition primitive for teleosts, and that D2 and A3 are primitive for acanthomorphs.