The Stapes of Acanthostega gunnari and the Role of the Stapes in Early Tetrapods

Abstract

Acanthostega gunnari is a tetrapod from the Upper Devonian of East Greenland, and is therefore one of the earliest tetrapod taxa for which skeletal remains are known. It was exactly contemporary with Ichthyostega (Jarvik 1952, 1980), a much more widely known form, but recent discoveries in Greenland (Bendix-Almgreen, Clack, and Olsen 1988) have shown that in many ways Ichthyostega and Acanthostega are quite different (Clack 1988a,b). Apart from primitive characters, they have little in common, suggesting early diversification among tetrapods.