A new species of Protopterus and a revision of Ceratodus humei (Dipnoi: Ceratodontiformes) from the Late Cretaceous Mut Formation of eastern Dakhleh Oasis, western desert of Egypt

Three lungfish species are recognized from tooth plates recovered from shales of the Mut Formation (Qusseir Group) in eastern Dakhleh Oasis. Ceratodus humei Priem, 1914 is identified on characters shared with the type specimen, and Neoceratodus africanus Haug, 1905 on characters shared with the type specimen and specimens assigned to this species by subsequent authors. Protopterus crassidens sp. nov, is represented by two recently found plates, as well as two plates previously considered to represent Ceratodus or Protopterus humei. These plates all bear three ridges and crests, unusually heavy mesial ridges, crushing bollard-like buccal cusps to the mesial ridges and thick, robust buccal margins. The status and characteristics of C. humei are reviewed and the general problems of interspecific variation of fossil lungfish tooth plates and species recognition based on tooth plates are discussed. The diagnosis of C. humei is revised and the species returned to its original generic assignment, based mainly on the broad sample of tooth plates from Dakhleh Oasis. This sample demonstrates that many tooth plates assigned to this species subsequent to its original description do not belong within C. humei. New specimens of N. africanus are described from Bahariya Oasis.