Phylum Chordata Bateson, 1885 - chordates
   Subphylum Vertebrata Cuvier, 1812 - vertebrates
     Superclass Agnatha Haeckel, 1895 see Class Agnatha Cope, 1889
       Class Monorhina Haeckel, 1895 see Class Cephalaspidomorphi Moy-Thomas & Mile, 1971
         1 Subclass Hyperoartii see Order Petromyzontiformes Berg, 1940
         2 Subclass Hyperotreti