Class †Placodermi McCoy, 1848 Order †Arthrodira Woodward, 1891 see [unranked] Arthrodira Woodward, 1891 Genus †Homosteus Woodward, 1891 see Genus Homostius Asmuss, 1856 1 †Homosteus sulcatus Kutorga, 1837 see Homostius sulcatus Kutorga, 1837