Chordata Bateson, 1885 - chordates Class †Ostracophori Order †Heterostraci Lankester, 1868 - heterostracans see Subclass Heterostraci Lankester, 1868 Family †Astraspidae Eastman, 1917 [monotypic] see Family Astraspididae Eastman, 1917, nom. praeval. Genus †Astraspis Walcott, 1892