Devonian osteolepiform fishes from East Greenland.

Abstract

The Middle and Upper Devonian deposits of East Greenland have yielded several osteolepiform fishes, of which only two, the osteolepid Gyroptychius groenlandicus Jarvik, 1950 and the rhizodontid Eusthenodon waengsjoei Jarvik, 1952 have been described previously. This paper gives new information on the structure of these two species. Three new forms are described: two osteolepids and a rhizodontid. The squamation is described and analysed, and evolutionary trends in osteolepiforms are discussed. The large collections of Remigolepis from East Greenland are discussed taxonomically, the importance of knowledge of variation in palaeontological species is emphasised, and the validity of the antiarch genus Hillsaspis Stensio and the osteolepiform genera Ectosteorhachis Cope and Eustenopteron Whiteaves is tested. In order to emphasise the fundamental differences between the Porolepiformes and the Osteolepiformes, the endoskeletal shoulder girdles in the porolepiform Glyptolepis groenlandica and the osteolepiform Eustenopteron foordi are illustrated. -from Author