Class Mammalia Linnaeus, 1758 - mammals
   Subclass Theria Parker & Haswell, 1897
     Order Didelphimorphia Gill, 1872
       Family Didelphidae Gray, 1821 - American opossums
         Subfamily Didelphinae Gray, 1821
           Genus Monodelphis Burnett, 1830 - short-tailed opossums
             Monodelphis maraxina Thomas, 1923 - Marajó short-tailed opossum