A primitive dipnoan fish from the Lower Devonian of Germany.

Abstract

A detailed description of a partial skull of the earliest yet known dipnoan, Dipnorhynchus lehmanni Westoll from the Hunsriickschiefer (Upper Siegenian, Lower Devonian) of the Bundenbaeh area, is given. This skull shares with D. sussmilchi (Eth. jfil.) from the Middle Devonian of Australia a number of features believed to be primitive, and in its palatal structures shows features apparently intermediate between those of Dipnoi and Rhipidistia. Analysis of many features of resemblance and difference between Dipnoi and Rhipidistia is undertaken, and it is shown that these groups show divergent modification from a common ancestral pattern, and that Dipnorhynchus shows many annectent features.