A shark turns into an undetermined crocodylian: the case of Acanthias bicarinatus Sismonda, 1849

- The holotype and only specimen referred to the Early Miocene shark Acanthias bicarinatus Sismonda, 1849 is housed in the collections of the Museo di Geologia e Paleontologia dell'Universit & agrave; degli Studi di Torino and was collected from the serpentinite sandstone of the middle-late Burdigalian Termofour & agrave; Formation of the Torino Hill. The specimen, formerly interpreted as a fragment of a squalid dorsal -fin spine, is reinterpreted herein as an isolated crocodylian tooth. The validity of the species Acanthias bicarinatus is therefore reconsidered and referred to as a nomen dubium. The tooth, replaced while the crocodylian was alive, was deposited in a near-shore marine environment at a time when modern crocodylian lineages were already widespread along the northern sector of the Mediterranean area.