Article: The axial skeleton of the Carboniferous amphibian Pteroplax cornutus

The vertebrae and ribs of the Carboniferous amphibian Pteroplax cornutus Hancock and Atthey, 1868 are described. The vertebrae are embolomerous and in most respects similar to those of the much-larger embolomere Eogyrinus attheyi Watson, 1926. Pteroplax vertebrae differ from those of Eogyrinus in possessing intercentra which are as thick dorsally as ventrally and in the presence of a supraneural canal in at least the anterior trunk vertebrae. The supraneural canal may have housed a longitudinal ligament serving to strengthen an elongate presacral vertebral column. The trunk centra of sub-adult individuals exhibit large notochordal foramina, and the intercentra lack a ventro-lateral covering of periosteal bone. The precocious development of the lateral boss in such juvenile intercentra suggests that this structure, rather than the depression ventral to it in the fully formed centrum, formed the site of the capitular articulation.