Vertebrata Cuvier, 1812 - vertebrates
   Gnathostomata
     Teleostomi
       Tetrapoda Hatschek & Cori 1896 [Gauthier, Kluge & Rowe 1988]
         Amniota Haeckel, 1866 [Gauthier, Kluge & Rowe 1988] - amniotes
           Class Reptilia Linnaeus, 1758 [paraphyletic] - reptiles
             Order †Ichthyopterygia Blainville, 1835 [coordinate rank]
               1 ?Family †Hupehsuchidae
               2 Family †Utatsusauridae McGowan & Motani, 2003
               3 Family †Omphalosauridae (Merriam, 1906)
               4 Family †Mixosauridae Baur, 1887
               5 Family †Shastasauridae Merriam, 1902
               6 Family †Ichthyosauridae Bonaparte, 1841
               7 Family †Stenopterygiidae (Kühn, 1934)
               8 Family †Protoichthyosauridae Appleby, 1979
               9 Family †Leptopterygiidae Kuhn, 1934