Chordata Bateson, 1885 - chordates
   Class †Ostracophori
     Order †Heterostraci Lankester, 1868 - heterostracans see Subclass Heterostraci Lankester, 1868
       08 Family †Thelodontidae see Family Coelolepididae Pander, 1856
       09 Family †Psammosteidae Traquair, 1896
       10 Family †Astraspidae [monotypic]
       11 Family †Drepanaspidae [monotypic] see Family Psammosteidae Traquair, 1896
       12 Family †Ceraspidae nom. illeg. [monotypic]
       13 Family †Pteraspidae see Family Pteraspididae Claypole, 1885