[Phylum] Chordata Bateson, 1885 - chordates
   Subphylum Craniata auct.
     Infraphylum Vertebrata Lamarck, 1801 - vertebrates
       Superclass †Pteraspidomorphi Goodrich, 1909 [monotypic]
         Class †Pteraspidomorpha
           Subclass †Heterostraci Lankester, 1868
             01 Family †Ariaspididae Elliott & Swift, 2010
             02 Order †Cardipeltiformes Bryant, 1933 [monotypic]
             03 Order †Corvaspidiformes Stensiö, 1964 [monotypic]
             04 Order †Lepidaspidiformes Halstead, 1993 [monotypic]
             05 Order †Tesseraspidiformes Halstead, 1962 [monotypic]
             06 Order †Traquairaspidiformes Stensio, 1958 [monotypic]
             07 Order †Tolypelepidiformes [monotypic]
             08 Order †Cyathaspidiformes Kiaer, 1930
             09 Order †Pteraspidiformes Berg, 1940