Kingdom [Animalia] Linnaeus, 1758 - animals
   Subkingdom Metazoa Haeckel, 1874 see Kingdom Animalia Linnaeus, 1758
     Division Eumetazoa Butschli, 1910 see Subkingdom Eumetazoa Butschli, 1910
       Subdivision Bilateralia
         Phylum Chordata Bateson, 1885 - chordates
           Subphylum Vertebrata Cuvier, 1812 - vertebrates
             Class Reptilia Linnaeus, 1758 - reptiles
               Subclass Lepidosauria Duméril & Bibron, 1839
                 Order Squamata Oppel, 1811
                   Suborder Serpentes Linnaeus, 1758 - snakes
                     Infraorder Caenophidia Hoffstetter, 1939 see Superfamily Xenophidia
                       Family Crotalidae Oppel, 1811 see Subfamily Crotalinae Oppel, 1811
                         Genus Crotalus Linnaeus, 1758
                           Crotalus viridis (Rafinesque, 1818) - western rattlesnake