[Phylum] Chordata Bateson, 1885 - chordates
   Subphylum Craniata auct.
     Infraphylum Vertebrata Lamarck, 1801 - vertebrates
       Superclass †Pteraspidomorphi Goodrich, 1909 [monotypic]
         Class †Pteraspidomorpha
           Subclass †Heterostraci Lankester, 1868
             Order †Pteraspidiformes Berg, 1940
               Suborder †Psammosteoidei Kiaer, 1932
                 1 Family †Drepanaspididae Traquair, 1900, nom. praeval.
                 2 Family †Guerichosteidae Tarlo, 1965
                 3 Family †Obrucheviidae Tarlo, 1965, "nom. praeval."
                 4 Family †Pycnosteidae Tarlo, 1962
                 5 Family †Psammolepididae Tarlo, 1962
                 6 Family †Psammosteidae Traquair, 1896