The oldest Gondwanan record of the extinct durophagous hybodontiform chondrichthyan, Strophodus from the Bajocian of Morocco

Abstract

Abstract Strophodus is a speciose and geographically widespread taxon of large durophagous hybodontiform chondrichthyan, with a stratigraphic range extending from Middle Triassic to the Early Cretaceous. Here, we describe a new species of Strophodus, S. atlasensis sp. nov., based on an incomplete articulated dentition recovered from marine Bajocian deposits of the eastern High Atlas Mountains in Morocco. The new species is diagnosed by a unique combination of dental characters that includes, among others, the presence of triangular first lateral teeth, mesio-distally wide and bulbous second lateral teeth without an occlusal crest or dome and uniquely shaped first posterior teeth that are shorter mesio-distally than being labio-lingually long, as well as small second posterior teeth whose roots protrude below the crowns to meet each other in an efficient interlocking manner. The holotype and only specimen of Strophodus atlasensis sp. nov. represents the hitherto oldest known record of Strophodus from Gondwana and the first record of that genus from the Bajocian, thus adding valuable novel information to our incomplete understanding of the evolutionary history of extinct hybodontiform chondrichthyans.

Keywords

• Chondrichthyes
• Middle Jurassic
• Taxonomic diversity
• Palaeobiogeography