†Placodermi McCoy, 1848 †Arthrodira Woodward, 1891 †Brachythoraci Gross, 1932 †Eubrachythoraci Miles, 1971 †Pachyosteomorphi Stensiö, 1944 - pachyosteomorphs Genus †Kiangyousteus Liu, 1955, incertae sedis [monotypic] 1 †Kiangyousteus yohii Liu, 1955