Phylum Euarthropoda Lankester, 1904 see [unranked] Euarthropoda Subphylum †Artiopoda Hou & Bergström, 1997 Superclass †Trilobitomorpha Størmer, 1944 Subclass †Conciliterga Hou & Bergström, 1997 Family †Helmetiidae Simonetta & Delle Cave, 1975 Genus †Skioldia X. Hou & J. Bergström, 1997