[Phylum] Chordata Bateson, 1885 - chordates
   Subphylum Craniata auct.
     Infraphylum Vertebrata Lamarck, 1801 - vertebrates
       Superclass †Thelodontomorphi Jaekel, 1911 [monotypic]
         Class †Thelodonti Jaekel, 1911
           Order †Furcacaudiformes Wilson & Caldwell, 1998 - fork-tailed thelodonts
             Family †Nikoliviidae Karatajūtė-Talimaa, 1978
               1 Genus †Nikolivia Karatajūtė-Talimaa, 1978