Subclass †Heterostraci Lankester, 1868
   Family †Cyathaspididae Kiaer, 1932, nom. praeval.
     Subfamily †Cyathaspidinae [paraphyletic]
       1.1 Genus †Torpedaspis Broad & Dineley, 1973
       1.2 †Vernonaspis sekwiae Denison, 1964
       2.1 Genus †Dikenaspis Denison, 1963
       2.2.1.1 Genus †Cyathaspis Lankester, 1865
       2.2.1.2 †Vernonaspis tortucostata Elliott, Lassiter & Blieck, 2021, orth. inval. see Vernonaspis tortucosta Dineley & Loeffler, 1976
       2.2.2.1 Genus †Capitaspis Elliott, 2013
       2.2.2.2.1 Genus †Pionaspis Denison, 1964
       2.2.2.2.2.1-n Genus †Archegonaspis Jaekel, 1927 [sister group to excluded taxa]