[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 †Cyathaspidiformes Kiaer, 1930
               1 Suborder †Amphiaspidoidei
               2 Suborder †Hibernaspidoidei
               3 Suborder †Siberiaspidoidei [monotypic]
               4 Suborder †Cyathaspidoidei