Chordata Bateson, 1885 - chordates
   Class Elasmobranchii Bonaparte, 1838 see Subclass Elasmobranchii Bonaparte, 1838
     Subclass Selachii see Subdivision Selachii
       Order †Ichthyotomi (Cope)
         36 Family †Xenacanthidae Fritsch, 1889
         37 Family †Cladodontidae
         38 Family †Chondrenchelyidae Berg, 1940 [monotypic]
         39 Family †Gyracanthidae Woodward, 1906