Class †Placodermi McCoy, 1848
   Order †Arthrodira Woodward, 1891 see [unranked] Arthrodira Woodward, 1891
     Suborder †Brachythoraci Gross, 1932
       †"Migmatocephala"
         Family †Homostiidae Eastman, 1907
           ?Genus †Atlantidosteus H. Lelièvre, 1984
             1 †Atlantidosteus pacifica G.C. Young, 2003
             2 †Atlantidosteus hollardi H. Lelièvre, 1984