After Li, Grande & Wilson, 1997, Zhang, 1998 and Hilton, 2003, with Recent species from Froese & Pauly, 2001 [“The Fishbase”]

Family -level taxonomy of osteoglossiforms.

<==o Osteoglossiformes Regan, 1909 (Bony-tongue fishes; arapaimakalat)
   |-- †Tanolepis ningjiagouensis (Jin, 1991) Jin, 1994 [Tanichthys Jin, 1991, preoccupied]
   `--+-- Osteoglossoidei Regan, 1909 [Osteoglossidae sensu Li, Grande & Wilson, 1997] (arapaimamaiset)
      `--o Notopteroidei (teräkalamaiset)
         |--o †Ostariostomidae Schaeffer, 1949
         |  |?- †Thaumaturus intermedius M. Eoc. L. Mioc. Eu. [Thaumaturidae] [also treated as a salmoniform?]
         |  `-- †Ostariostoma wilseyi Schaeffer, 1949; U. Cret. L. Pal. WNA.
         `--+--o Mormyroidea (norsukalat; elephantfishes)
            |  |-- Gymnarchus niloticus Cuvier, 1829 [Gymnarchidae] (nauhanorsukala; Aba)
            |  `-- Mormyridae (varsinaiset norsukalat) [N: 18/198] [FB: 18/184]
            `--o Notopteroidea (teräkalansukuiset)
               `--o Notopteridae (teräkalat; Featherbacks or knifefishes)
                  |-- †Palaeonotopterus greenwoodi Forey, 1997 [incl.? Plethodus libycus Weiler, 1935 (nomen dubium, type lost)]
                  |-- Xenomystus nigri (Günther, 1868) (African knifefish)
                  `--+--o Chitala
                     |  |-- C. blanci (d'Aubenton, 1965) (Indochina featherback)
                     |  |-- C. chitala (Hamilton, 1822) (Clown knifefish)
                     |  |-- C. lopis (Bleeker, 1851) (Giant featherback)
                     |  `-- C. ornata (Gray, 1831) (Clown featherback)
                     |--o Notopterus L. Olig.-R. EInd. R. SAs. ()? [1 Recent species]
                     |  `-- N. notopterus (Pallas, 1769) (Bronze featherback)
                     `--o Papyrocranus
                        |-- P. afer (Günther, 1868) (Reticulate knifefish)
                        `-- P. congoensis (Nichols & La Monte, 1932)

Reference(s):