Ecdysozoa Aguinaldo, Turbeville, Linford, Rivera, Garey, Raff & Lake 1997, nom. cl. inval. - ecdysozoans see Clade Ecdysozoa Aguinaldo, Turbeville, Linford, Rivera, Garey, Raff & Lake 1997 [Lake, Halanych, Servin & Garey 2020]
   Panarthropoda Nielsen, 1995 - panarthropods
     Arthropoda Siebold, 1848 - arthropods see Phylum Arthropoda Siebold, 1848
       Chelicerata s.l. Heymons, 1901 see Superclass Chelicerata Heymons, 1901
         Euchelicerata Weygoldt & Paulus, 1979
           1 Xiphosura Latreille, 1802 - horseshoe crabs see Class Xiphosura Latreille, 1802
           2 Arachnida Cuvier, 1812 see Class Arachnida Lamarck, 1801