Article: On Crassigyrinus scoticus Watson, a primitive amphibian from the Lower Carboniferous of Scotland

The unique holotype of Crassigyrinus scoticus Watson is almost certainly from the Visean Gilmerton Ironstone of Scotland, as suggested by Watson. It consists only of the right side of a large primitive amphibian skull with a very long postorbital region. The pattern of dermal bones, which includes a well-developed preopercular, is intermediate in configuration between that of a rhipidistian fish and the earliest Amphibia, the ichthyostegids. Crassigyrinus may also have a rhipidistian-like course of the infraorbital lateral line system, but in the amphibian form of open sulci. The configuration of bones round the nostril is probably also similar to that of osteolepiform Rhipidistia. 'Macromerium' scoticum Lydekker, a lower jaw from Gilmerton, formerly attributed to Crassigyrinus, is more probably Loxomma allmanni. Crassigyrinus is too large and far too late to be anything but a distant relict of the ancestral tetrapod stock. A new order of labyrinthodont Amphibia, the Palaeostegalia, is proposed for Crassigyrinus.