Cornuata

Abstract: The Osteostraci are a morphologically diverse group of jawless fishes considered as sister taxon to jawed vertebrates. Fossil Osteostraci therefore have wide-reaching ramifications for our understanding of the origin and evolution of gnathostomes. Their utility in this context is currently impeded by rudimentary taxonomy of faunas from the United Kingdom. Principal among these is a well-preserved, previously undescribed fauna from the Early Devonian (Lochkovian) of Wayne Herbert Quarry, Herefordshire. Here we provide a description of new osteostracan material from this fauna. Anatomical observations of the character-rich, taxonomically informative headshield, combined with quantitative measurements, have permitted identification of 15 variable characters. From these, seven discrete morphogroups are recognized and used to establish the taxonomy of the material. This includes two new species of Zenaspididae (Zenaspis waynensis and Diademaspis janvieri), two new species of Cornuata incertae sedis (J...