Chelicerata Heymons, 1901
   Scorpiones Koch, 1837 - scorpions
     †Holosternina Kjellesvig-Waering, 1986
       Superfamily †Palaeoscorpoidea Dunlop, Penney & Jekel, 2010, orth. inval. [monotypic] see Superfamily Palaeoscorpioidea Lehmann, 1944
         1 Family †Palaeoscorpionidae Lehmann, 1944, orth. inval. [monotypic] see Family Palaeoscorpiidae Lehmann, 1944