Chelicerata Heymons, 1901
   †Eurypterida Burmeister, 1843 - eurypterids
     †Stylonurina Diener, 1924
       Superfamily †Kokomopteroidea Kjellesvig-Waering, 1966
         1 Family †Kokomopteridae Kjellesvig-Waering, 1966
         2 Family †Hardieopteridae Tollerton, 1989