Evolution of the sense of hearing in vertebrates

Abstract

This paper briefly recapitulates work on the preterrestrial phase of the evolution of hearing which was published in detail elsewhere. Following this, the problem of the origin of the terrestrial middle ear is examined in some detail, and it is demonstrated that Eusthenopteron, and probably other rhipidistians as well, possessed an eardrum. This drum was formed by the fusion of the distal surface of a spiracular diverticulum and a ligament between parietal shield and squamosal. It is further demonstrated that the geometry of this eardrum in relation to the middle-ear cavity was adequate to allow the fish to make the transition from aquatic hearing to terrestrial hearing without loss of sensitivity. © 1966 by the American Society of Zoologist.