Superphylum Deuterostomia Grobben, 1908 - deuterostomes see Infrakingdom Deuterostomia Grobben, 1908
   Phylum Chordata Bateson, 1885 - chordates
     Subphylum Craniata auct.
       Vertebrata Lamarck, 1801 - vertebrates see Infraphylum Vertebrata Lamarck, 1801
         Superclass †Pteraspidomorphi Goodrich, 1909 [monotypic]
           Class †Pteraspidomorphi Goodrich, 1909 see Class Pteraspidomorpha
             Subclass †Heterostraci Lankester, 1868
               Order †Cyathaspidiformes Kiaer, 1930
                 1 Family †Amphiaspididae Obruchev, 1939
                 2.1 [plesion] Genus †Nahanniaspis Dineley & Loeffler, 1976
                 2.2 Family †Cyathaspididae Kiaer, 1932, nom. praeval.