Plicatodus jordani n. g., n. sp., a new xenacanthid shark from the Lower Permian of Europe (Saar-Nahe Basin, Germany)

By means of a partial anterior skeleton within a nodule, a new xenacanthid shark, Plicatodus jordani n. g., n. sp., is described from the Lower Permian of the SW-German Saar-Nahe basin. Its tricuspidate teeth show wavy cristae of hybodontoid pattern, and an extremely flattened base with a coronal button, histologically made of orthodentine. These characteristics are different from the currently known xenacanthid genera. The Bohemian "Orthacanthus" plicatus belongs to the same genus and is reviewed here. A cladogram of the order Xenacanthida is given, based only on hard parts, using ctenacanthids for outgroup comparison.