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
Genus †Palaeopisthacanthus Petrunkevitch, 1913