Phylum [Vertebrata] (Lamarck, 1801)
   Class Reptilia Linnaeus, 1758 - reptiles
     Subclass Diapsida Osborn, 1903 - diapsids see Clade Diapsida Osborn 1903 [Gauthier & de Queiroz 2020]
       Order †Ichthyosauria Blainville, 1835
         1 Family †Shastasauridae Merriam, 1902
         2 Family †Mixosauridae Baur, 1887
         3 Family †Ichthyosauridae Bonaparte, 1841
         4 Family †Stenopterygiidae (Kühn, 1934)
         5 Family †Leptopterygiidae Kuhn, 1934