Chelicerata Heymons, 1901
   †Eurypterida Burmeister, 1843 - eurypterids
     †Eurypterina Burmeister, 1843
       Superfamily †Onychopterelloidea Lamsdell, 2011 [monotypic]
         Family †Onychopterellidae Lamsdell, 2011
           1 Genus †Alkenopterus Størmer, 1974
           2 Genus †Onychopterella Størmer, 1951
           3 Genus †Tylopterella Størmer, 1951