Didelphidae

Didelphidae is the opossum family, in the order Didelphimorphia, the largest order of marsupials in the Western Hemisphere, comprising one hundred twenty six species in eighteen genera. Opossums are native to the Americas, having originated in South America and later spread north through the Great American Interchange; the Virginia opossum is the only species found in the United States and Canada. They are typically small to medium sized, semi-arboreal omnivores with long snouts, a narrow braincase, and a prominent sagittal crest, and have an unusually high tooth count of fifty; the family name comes from Greek for double-wombed, referring to their reproductive anatomy.