a1 Royal Scottish Museum, Edinburgh
a2 Department of Geology, University of Newcastle upon Tyne.
Well preserved material of the crossopterygian fish Eusthenopteron enables fresh reconstructions and interpretations of its postcranial skeleton to be given. Comparisons throughout with other bony fishes show that it may be primitive in many features. Similarities with early amphibians such as the screw-shaped glenoid, the form of the humerus (on which an attempt to restore the pectoral musculature is based), the dorsal bicipital ribs and the possibility of a sacral attachment, throw much light on the origin of the tetrapod postcranial skeleton, particularly of the cheiropterygium. A functional analysis of the skeleton of Ensthenopteron is attempted, suggesting that it resembled the pike (Esox) in its mode of life and that it may have been capable of short journeys “walking” overland. The possible selective factors stimulating the evolution of such a fish, and further evolution to the tetrapod stage are discussed.
(Received June 09 1969)
(Revised July 23 1969)
* This paper was assisted in publication by a grant from the Carnegie Trust for the Universities of Scotland.