Class Aves Linnaeus, 1758 - birds see Subclass Aves Linnaeus, 1758
   Subclass Neornithes Gadow, 1893 see Clade Neornithes Gadow, 1893
     Infraclass Neoaves Sibley et al., 1988 see Subcohort Neoaves Sibley et al., 1988
       Parvclass Coraciae see Order Coraciiformes Forbes, 1884
         Superorder Bucerotimorphae see Suborder Bucerotes Fürbringer, 1888
           Order Bucerotiformes Fürbringer, 1888 see Infraorder Bucerotides Fürbringer, 1888
             Family Bucerotidae Vigors - hornbills
               Genus Tockus Lesson, 1830
                 Tockus albocristatus (Cassin, 1848) - white-crested hornbill see Tropicranus albocristatus (Cassin, 1848)
                 Tockus hartlaubi Gould, 1861 - black dwarf hornbill
                 Tockus camurus Cassin, 1857 - red-billed dwarf hornbill
                 Tockus monteiri Hartlaub, 1865 - Monteiro's hornbill
                 Tockus erythrorhynchus (Temminck, 1823) - red-billed hornbill
                 Tockus flavirostris (Rüppell, 1835) - eastern yellow-billed hornbill
                 Tockus leucomelas (M.H.K. Lichtenstein, 1842) - southern yellow-billed hornbill
                 Tockus jacksoni (Ogilvie-Grant, 1891) - Jackson's hornbill
                 Tockus deckeni (Cabanis, 1869) - Von der Decken's hornbill
                 Tockus alboterminatus (Büttikofer, 1889) - crowned hornbill
                 Tockus bradfieldi (Roberts, 1930) - Bradfield's hornbill
                 Tockus hemprichii (Ehrenberg, 1833) - Hemprich's hornbill
                 Tockus nasutus (C. Linnaeus, 1766) - African grey hornbill
                 Tockus pallidirostris (Hartlaub & Finsch, 1870) - pale-billed hornbill
                 Tockus fasciatus (Shaw, 1811) - African pied hornbill
                   1 Tockus fasciatus semifasciatus (Hartlaub, 1855) - allied hornbill
                   2 Tockus fasciatus fasciatusᵀ (Shaw, 1811) - African pied hornbill