Chelicerata Heymons, 1901
   Scorpiones Koch, 1837 - scorpions
     Orthosternina Pocock, 1911 see Infraorder Orthosterni Pocock, 1911
       Superfamily Scorpionioidea Dunlop, Penney & Jekel, 2010, orth. inval. see Superfamily Scorpionoidea Latreille, 1802
         Family †Palaeopisthacanthidae Kjellesvig-Waering, 1986
           1 Genus †Cryptoscorpius Jeram, 1994
           2 Genus †Palaeopisthacanthus Petrunkevitch, 1913