Chelicerata Heymons, 1901
Count: 2c;12o; †6o;2f;23g
   †Eurypterida Burmeister, 1843 - eurypterids
  Count: [†g] †21f;73g [26 Dec 2020]
     †Eurypterina Burmeister, 1843
    Count: [†g] †13f;42g [26 Dec 2020]
       †Diploperculata Lamsdell, Hoşgör & Selden, 2013
      Count: [†g] †6f;25g [26 Dec 2020]
         Superfamily †Adelophthalmoidea Tollerton, 1989 [monotypic]
        Count: [†g] †1f;6g [25 Dec 2020]
           1 Family †Adelophthalmidae Tollerton, 1989
          Count: [†g] †6g [25 Dec 2020]