Subclass †Heterostraci Lankester, 1868 Family †Cyathaspididae Kiaer, 1932, nom. praeval. Subfamily †Cyathaspidinae [paraphyletic] †Vernonaspis tortucostata Elliott, Lassiter & Blieck, 2021, orth. inval. see Vernonaspis tortucosta Dineley & Loeffler, 1976