†Placodermi McCoy, 1848 †Arthrodira Woodward, 1891 †Brachythoraci Gross, 1932 †Eubrachythoraci Miles, 1971 †Coccosteomorphi Stensiö, 1944 - coccosteomorphs Family †Coccosteidae Asmuss, 1856 Genus †Coccosteus Agassiz, 1844 †Coccosteus cuspidatus Miller, 1841 ex Agassiz