After Montellano, 1988, Cifelli, 1990, Johanson, 1994, McKenna & Bell, 1997 and Zonneveld, Gunnell & Bartels, 2000

<==o †Alphadontidae Marshall, Case & Woodburne, 1990 [Alphadontia Archer, 1984; Didelphidae: Alphadontinae Marshall, Case & Woodburne, 1990 sensu McKenna & Bell, 1997]
   |--o †Albertatherium Fox, 1971
   |  |-- †A. primus Fox, 1971
   |  `-- †A. secundus Johanson, 1994
   `--o †Alphadon Simpson, 1927 [incl. Protalphadon Cifelli, 1990 sensu McKenna & Bell, 1997]
      |-- †A. attaragos Lillegraven & McKenna, 1986
      |-- †A. austrinum Sigé, 1971 [Peradectes austrinum (Sigé, 1971)]
      |-- †A. clemensi Eaton, 1993
      |-- †A. eatoni Cifelli & de Muizon, 1998
      |-- †A. halleyi Sahni, 1972
      |-- †A. jasoni Storer, 1991
      |-- †A. lillegraveni Eaton, 1993
      |-- †A. marshi Simpson, 1927
      |-- †A. perexiguus Cifelli, 1994
      |-- †A. sahnii Lillegraven & McKenna, 1986 [jr. synon. to A. halleyi Sahni, 1972??]
      `-- †A. wilsoni Lillegraven, 1969

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