†Placodermi McCoy, 1848 †Arthrodira Woodward, 1891 †Brachythoraci Gross, 1932 †Eubrachythoraci Miles, 1971 †Pachyosteomorphi Stensiö, 1944 - pachyosteomorphs ?Family †Rachiosteidae "Stensiö, 1963" see Family Rhachiosteidae Stensiö, 1963