[Phylum] [Arthropoda] Siebold, 1848 - arthropods
   Chelicerata Heymons, 1901
     Euchelicerata Weygoldt & Paulus, 1979
       Xiphosura Latreille, 1802 - horseshoe crabs see Class Xiphosura Latreille, 1802
         Prosomapoda Lamsdell, 2013
           [Class] Xiphosura Latreille, 1802 [monotypic] - horseshoe crabs
             [Order] Xiphosurida Latreille, 1802
               [Suborder] Limulina Richter & Richter, 1929
                 1 Genus †Bellinuroopsis Chernyshev, 1933
                 2 Family †Rolfeiidae Selden & Siveter, 1987 [monotypic]
                 3 Superfamily †Paleolimuloidea Raymond, 1944 [monotypic]
                 4 Superfamily Limuloidea Leach, 1819