The origin of the primitive tetrapod limb

Abstract

Arhipidistian paired fin, made to assume the position of a primitive tetrapod limb, would suffer certain modifications which throw light on the origin of the latter and on the homology of its elements. The new theory here stated , and that of Gregory and Raven (from which it differs in several points), are radically different from all hitherto proposed. The proto -tetrapod pectoral and pelvic fins were of similar structure. Each consisted of five axial mesomeres, each bearing distally a simple preaxial radial and an actual or potential postaxial process; a rudimentary sixth mesomere may have been present.