Opossum Skeleton (Didelphis virginiana). Originally native to the eastern United States, the Virginia Opossum was intentionally introduced into the West during the Great Depression, probably as a source of food. Its range has been expanding steadily northwards, thanks in part to more plentiful, man-made sources of fresh water, increased shelter due to urban encroachment, and milder winters. Its range has extended into Ontario, Canada. Display at the Royal Tyrrell Museum, Drumheller, Alberta, Canada.