Subphylum [Vertebrata] Cuvier, 1812 - vertebrates
   Class Agnatha Cope, 1889
     Subclass †Thelodonti Kiaer, 1932
       Order †Thelodontiformes Kiaer, 1932
         Family †Nikoliviidae Karatajūtė-Talimaa, 1978
           1 Genus †Nikolivia Karatajūtė-Talimaa, 1978
           2 Genus †Chattertonodus Märss, Wilson & Thorsteinsson, 2002 [monotypic]