†Placodermi McCoy, 1848 Status: fossil †Arthrodira Woodward, 1891 Status: fossil †Brachythoraci Gross, 1932 Status: fossil †Eubrachythoraci Miles, 1971 Status: fossil †Pachyosteomorphi Stensiö, 1944 - pachyosteomorphs Status: fossil †Aspinothoracidi Stensiö, 1959 Status: fossil Genus †Heintzichthys Whitley, 1933 Status: fossil 1 †Heintzichthys gouldii (Newberry, 1885) Status: fossil