Vertebrata Cuvier, 1812 - vertebrates see Infraphylum Vertebrata Lamarck, 1801 Gnathostomata Class †Placodermi McCoy, 1848 Order †Arthrodira Woodward, 1891 see [unranked] Arthrodira Woodward, 1891 Suborder †Brachythoraci Gross, 1932 Superfamily †Heterosteoidea Denison, 1984 [monotypic] Family †Heterosteidae Jaekel, 1903