The Late Jurassic neoselachian Macrourogaleus Fowler, 1947 is a palaeospinacid shark (Elasmobranchii; Synechodontiformes)

The taxonomy of palaeospinacid sharks (Chondrichthyes, Neoselachii) is reviewed. New skeletal material from the famous Late Jurassic lithographic limestones of southern Germany (Solnhofen area and Nusplingen) enables identification of the morphological and dental differences between Synechodus and Paraorthacodus. These taxa were hitherto known mainly by isolated teeth or a few mostly fragmentary skeletal remains from the Early and Late Jurassic and Late Cretaceous. Differences not only include dental features but also the presence of a single dorsal fin in Paraorthacodus compared to two in Synechodus. Fin spines are restricted to Early Jurassic specimens. A detailed examination of the small neoselachian shark, Macrourogaleus hassei, from the lithographic limestones of the Solnhofen area revealed that this taxon displays the characteristic synechodontiform tooth root morphology (pseudopolyaulacorhize) and a single dorsal fin as seen in Paraorthacodus. Consequently,Macrourogaleus is assigned to the Palaeospinacidae. It differs from Paraorthacodus, however, in the presence of a single row of enlarged placoid scales on the caudal crest.