Vertebrata Cuvier, 1812 - vertebrates
   Class Agnatha Cope, 1889 [paraphyletic]
     Subclass †Pteraspidomorphi Goodrich, 1909 see Class Pteraspidomorphi Goodrich, 1909
       Order †Heterostraci Lankester, 1868 - heterostracans see Subclass Heterostraci Lankester, 1868
         Family †Cyathaspididae Flower & Wayland-Smith, 1952
           01 Genus †Alainaspis Elliott & Dineley, 1985
           02 Genus †Allocryptaspis Whitley, 1940
           03 Genus †Americaspis White & Moy-Thomas, 1941
           04 Genus †Anglaspis Jaekel, 1927
           05 Genus †Archegonaspis Jaekel, 1927
           06 Genus †Ariaspis Denison, 1963
           07 Genus †Asketaspis Dineley & Loeffler, 1976
           08 Genus †Boothiaspis Broad, 1973
           09 Genus †Ctenaspis Kiaer, 1930
           10 Genus †Cyathaspis Lankester, 1865
           11 Genus †Davelaspis Blieck, 1983
           12 Genus †Dikenaspis Denison, 1963
           13 Genus †Dinaspidella Strand, 1934
           14 Genus †Homalaspidella Strand, 1934
           15 Genus †Irregulareaspis Zych, 1931
           16 Genus †Liliaspis
           17 Genus †Listraspis Denison, 1964
           18 Genus †Nahanniaspis Dineley & Loeffler, 1976
           19 Genus †Pionaspis Denison, 1964
           20 Genus †Poraspis Kiaer, 1930
           21 Genus †Ptomaspis Denison, 1963
           22 Genus †Seretaspis Stensiö, 1958
           23 Genus †Steinaspis Obruchev, 1964
           24 Genus †Tolypelepis Pander, 1856
           25 Genus †Torpedaspis Broad & Dineley, 1973
           26 Genus †Vernonaspis Flower & Wayland-Smith, 1952