Class Mammalia Linnaeus, 1758 - mammals
   Order Rodentia Bowdich, 1821 - rodents
     Suborder Sciurognathi (Tullberg, 1899) see Suborder Sciuromorpha Brandt, 1855
       Family Muridae Batsch, 1788 - rats, mice, hamsters, voles, lemmings, and gerbils
         Subfamily Sigmodontinae Wagner, 1843
           Genus Megadontomys Merriam, 1898 - Thomas's deer mouse
             1 Megadontomys cryophilus Musser, 1964
             2 Megadontomys nelsoni Merriam, 1898
             3 Megadontomys thomasi Merriam, 1898 - Thomas's deer mouse