Subclass †Heterostraci Lankester, 1868
   Family †Cyathaspididae Kiaer, 1932, nom. praeval.
     Subfamily †Boothiaspidinae Elliot, 2016
       1.1 Genus †Alainaspis Elliott & Dineley, 1985
       1.2 Genus †Boothiaspis Broad, 1973
       2 Genus †Phyllonaspis Elliot, 2016