Vertebrata Cuvier, 1812 - vertebrates see Infraphylum Vertebrata Lamarck, 1801
   Gnathostomata
     Class Chondrichthyes Huxley, 1880 - cartilaginous fishes
       Subclass Elasmobranchii Bonaparte, 1838 - shark-like fishes see Infraclass Elasmobranchii Bonaparte, 1838
         Superorder Euselachii Hay, 1902 see Subclass Euselachii Hay, 1902
           Order †Xenacanthida Glikman, 1964 see Order Xenacanthiformes Berg, 1955
             1 Family †Diplodoselachidae Dick, 1981
             2 Family †Xenacanthidae Geinitz, 1860