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
                         1 Genus Atheris Cope, 1862
                         2 Subfamily Azemiopinae
                         3 Subfamily Atractaspinae see Subfamily Aparallactinae
                         4 Subfamily Viperinae Oppel, 1811 - pitless vipers
                         5 Subfamily Crotalinae Oppel, 1811 - pit vipers