[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
                 Family †Psammosteidae Traquair, 1896
                   1 Genus †Psammosteus Agassiz, 1844
                   2 Genus †Placosteus Agassiz, 1845