Chelicerata Heymons, 1901
   Euchelicerata Weygoldt & Paulus, 1979
     1 Genus †Offacolus Orr, Siveter, Briggs, Siveter & Sutton, 2000
     2 Genus †Dibasterium Briggs, Siveter, Siveter, Sutton, Garwood & Legg, 2012
     3 Genus †Houia Selden, Lamsdell & Qi, 2015, incertae sedis
     4 Genus †Polystomurum Novozhilov, 1958, incertae sedis
     5 Genus †Thurandina Størmer, 1974, incertae sedis