Article: Cephalaspids from the Lower Devonian of Prince of Wales Island, Canada

A Lochkovian vertebrate assemblage from the Peel Sound Formation of northern Prince of Wales Island, Northwest Territories, Canada, includes numerous headshields resembling the osteostracan Parameteoraspis, together with several fragments suggesting Machairaspis. Five specimens of the former, distinct in their extended and diverging pectoral cornua, may be regarded as a conspecific variety. A possible advantage afforded by such cornua, in this and other species, may be their use in swimming and in disturbing the substrate during feeding. A similar role for the rostra of other osteostracans and eugaleaspids is suspected.