[Kingdom] Animalia Linnaeus, 1758 - animals
   Grade Enterozoa
     Grade Cœlomata
       Phylum Vertebrata (Lamarck, 1801)
         Branch Craniata Linnaeus, 1758
           Grade Gnathostoma
             Subgrade Pentadactyla lipobranchia
               Branch Monocondyla
                 Class Reptilia Linnaeus, 1758 - reptiles
                   Subclass Lepidosauria Duméril & Bibron, 1839
                     Branch Ophidia Latreille, 1804
                       Order Solenoglypha
                         Genus Crotalus Linnaeus, 1758