A new selenosteid arthrodire (‘Placodermi’) from the Late Devonian of Morocco

Abstract

A new genus and species of selenosteid arthrodire is described from the Late Devonian of Morocco. Driscollaspis pankowskiorum, gen. nov. sp. nov., is defined as a selenosteid with a shallow preorbital plate embayment of the central plate, a paranuchal plate embayment of the central plate as a deep embayment determined by the lateral and posterior lobe, a central plate expanded at the contact with the pineal plate as transverse anterior border, and a suborbital plate overlapping the postorbital plate. The dermal ornamentation is tubercular, forming patches of reticular ridges clustered around sensory-line canal junctions in plate centers. The sensory-line canals are distinctly raised just above the level of the dermal ornamentation, a unique character not previously recognized in any arthrodire but seen in some ptyctodontids. A new phylogenetic hypothesis supports the monophyly of the Selenosteidae within which this new taxon is resolved, but emphasizes also unresolved relationships among aspinothoracid arthrodires. The paleogeographic distribution of the Frasnian vertebrates from Morocco and especially the seleonsteids on the western margin of Gondwana and Laurussia are discussed, and the indication for a contact of both continents during the late Frasnian is emphasized.