living organisms see Clade Biota Wagner 2004 [Wiemann, de Queiroz, Rowe, Planavsky, Anderson, Gogarten, Turner & Gauthier 2020]
   Superkingdom Eukaryotae see Domain Eukaryota Chatton, 1925
     Kingdom Animalia Linnaeus, 1758 - animals
       Subkingdom Eumetazoa Butschli, 1910 see [unranked] Eumetazoa Bütschli, 1910
         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
                     Superfamily Colubroidea Oppel, 1811
                       Family Viperidae Oppel, 1811 - vipers and pit vipers
                         Subfamily Crotalinae Oppel, 1811 - pit vipers
                           1 Genus Crotalus Linnaeus, 1758
                           2 Genus Sistrurus Garman, 1883
                           3 Genus Calloselasma Cope, 1859
                           4 Genus Trimeresurus Lacepède, 1804
                           5 Genus Agkistrodon de Beauvois, 1799
                           6 Genus Bothrops Wagler, 1824
                           7 Genus Lachesis Daudin, 1803