[Phylum] [Arthropoda] Siebold, 1848 - arthropods
   Chelicerata Heymons, 1901
     Euchelicerata Weygoldt & Paulus, 1979
       01 Genus †Offacolus Orr, Siveter, Briggs, Siveter & Sutton, 2000
       02 Genus †Dibasterium Briggs, Siveter, Siveter, Sutton, Garwood & Legg, 2012
       03 Genus †Houia Selden, Lamsdell & Qi, 2015, incertae sedis
       04 Genus †Polystomurum Novozhilov, 1958, incertae sedis
       05 Genus †Thurandina Størmer, 1974, incertae sedis
       06 Xiphosura Latreille, 1802 - horseshoe crabs see Class Xiphosura Latreille, 1802
       07 [Order] †Chasmataspidida Caster & Brooks, 1956
       08 [Order] †Eurypterida Burmeister, 1843 - eurypterids
       09 [Order] Scorpiones Koch, 1837 - scorpions
       10 [Order] Opiliones Sundevall, 1833 - harvestmen
       11 [Order] †Phalangiotarbida Haase, 1890
       12 [Order] Pseudoscorpiones De Geer, 1778
       13.1 Genus †Schneidarachne Dunlop & Rössler, 2003
       13.2 [Order] Solifugae Sundevall, 1833
       14 [Order] Palpigradi Thorell, 1888 - palpigrades
       15 [Subclass] Acari Leach, 1817 - mites and ticks
       16 [Order] Ricinulei Thorell, 1876 - ricinuleids
       17 Pantetrapulmonata Shultz, 2007