Article: A systematic review of the placoderm genus Cosmacanthus and a description of acanthodian remains from the upper Devonian of Scotland

A number of fin spines were described by Duff (1842) from the Upper Devonian locality of Scat Craig, Scotland. Only one of these specimens was described by Agassiz (1845) as a fin spine. This was the holotype of Cosmacanthus malcolmsoni Agassiz, 1845. Denison (1978) later removed C. malcolmsoni from the Acanthodii and placed it in the Placodermi, but without a full systematic description. In this paper, Denison's (1978) opinion as to the affinity of C. malcolmsoni is confirmed. A full systematic description of C. malcolmsoni is presented, including a complete synonymy list. New material has recently been collected from Scat Craig, which can be ascribed to the Acanthodii, but is not well preserved and so is kept in open nomenclature. With C. malcolmsoni being placed within the Placodermi, the acanthodian remains represent the only known record of this group from the Upper Devonian of Scotland.