Chordata Bateson, 1885 - chordates
   Class †Arthrodira Woodward, 1891 - arthrodires see Order Arthrodiriformes Grande & Eastman, 1986
     Order †Arthrothoraci see Order Arthrodiriformes Grande & Eastman, 1986
       26 Family †Coccosteidae Asmuss, 1856
       27 Family †Dinichthyidae Newberry, 1885
       28 Family †Titanichthyidae Dean, 1901
       29 Family †Mylostomidae Dean, 1901, nom. illeg. see Family Mylostomatidae Woodward, 1891
       30 Family †Selenosteidae Dean, 1901
       31 Family †Phyllolepidae Woodward, 1891 see Family Phyllolepididae Woodward, 1891, nom. praeval.