Bransonelliformes - A new order of the Xenacanthimorpha (Chondrichthyes, Elasmobranchii)

Abstract

The order Bransonelliformes is erected for the genera Bransonella Harlton, 1933 and Barbclabornia Johnson, 2003 based on the distinct characters of an inverted V-nested pattern of ornamentation preliminary on the labial aspect at the tooth cusps, the presence of labial foramina, and the occasional occurrence of a centrally positioned lingual opening of a main nutrient canal at the bases of the teeth. The Bransonelliformes comprises the primitive sister group to the Xenacanthiformes within the Xenacanthimorpha.