[organisms] see Clade Biota Wagner 2004 [Wiemann, de Queiroz, Rowe, Planavsky, Anderson, Gogarten, Turner & Gauthier 2020]
   Eukaryotes see Domain Eukaryota Chatton, 1925
     Metazoa Haeckel 1874 - multicellular animals see Kingdom Animalia Linnaeus, 1758
       Bilateria Hatschek, 1888 - bilaterians see Subkingdom Bilateria Hatschek, 1888
         Deuterostomia Grobben, 1908 - deuterostomes see Infrakingdom Deuterostomia Grobben, 1908
           Phylum Chordata Bateson, 1885 - chordates
             Subphylum Vertebrata Cuvier, 1812 - vertebrates
               Class "Agnatha" Cope, 1889
                 Subclass †Pteraspidomorphi Goodrich, 1909 see Class Pteraspidomorphi Goodrich, 1909
                   1 Order †Astraspida (Berg, 1940) see Subclass Astraspida (Berg, 1940)
                   2.1 Order †Arandaspida see Subclass Arandaspida
                   2.2 Order †Heterostraci Lankester, 1868 - heterostracans see Subclass Heterostraci Lankester, 1868