Article: Morphology and relationships of the Upper Carboniferous aïstopod amphibian Ophiderpeton nanum

The holotype and only recorded specimen of the Carboniferous aistopod amphibian Ophiderpeton nanum Hancock and Atthey 1868 is described in detail and figured for the first time. The vertebrae, ribs, dermal squamation, and premaxilla are characteristic of Ophiderpeton and confirm that O. nanum is a member of that genus. The relationship of O. nanum to other described Ophiderpeton species is obscured by the absence of most of the skull in the holotype and by the apparently sub-adult nature of the specimen. The ventral osteoderms are, however, unusually filamentous for Ophiderpeton and it is suggested that O. nanum be retained as a distinct species, pending revision of the Ophiderpetontidae. A small isolated bone in the holotype may be an interclavicle, suggesting the retention of a vestigial pectoral girdle in ophiderpetontid aistopods.