Opossums are members of the marsupial order Didelphimorphia endemic to the Americas. The largest order of marsupials in the Western Hemisphere, it comprises 126 species in 18 genera. Opossums originated in South America and entered North America in the Great American Interchange following the connection of North and South America.
The Bolivian squirrel is a tree squirrel that is endemic to South America. Little is known of the species, which may represent a species complex.
The long-nosed short-tailed opossum, is an opossum species in Argentina and Brazil.
Handley's slender opossum is a species of opossum in the family Didelphidae. It is endemic to Colombia.
Thylamys is a genus of opossums in the family Didelphidae. The premaxillae are rounded rather than pointed. The females lack a pouch. The females' nipples are arranged in two symmetrical rows on the abdomen. All species but T. macrurus store fat in their tails., although this is not necessarily true for all species in the genus. Fossils belonging to the genus date back to the Miocene, with the oldest specimens being found in the Cerro Azul Formation of Argentina and the Honda Group of Colombia. Genetic studies indicate that the genus may have originated around 14 million years ago.
Gracilinanus is a genus of opossum in the family Didelphidae. It was separated from the genus Marmosa in 1989, and has since had the genera Cryptonanus, Chacodelphys, and Hyladelphys removed from it.
The Didelphinae are a subfamily of opossums consisting of 15 genera and 123 species. Specimens have been collected throughout the Americas, but are predominant in South and Central America.
Bishop's slender opossum is a small, arboreal marsupial opossum native to Brazil, Peru, and Bolivia. It somewhat resembles a placental rat or shrew.
The Cinderella fat-tailed mouse opossum is a species of opossum in the family Didelphidae. It is found in northern Argentina and southern Bolivia, in the eastern foothills of the Andes. Its dorsal fur is gray brown to dark brown. Its ventral fur is gray-based, except for the white to yellowish chest hairs. It has been distinguished from T. sponsorius by the well-developed postorbital ridges of the latter, but mitochondrial DNA sequence analysis does not support separate species status for sponsorius.
The Argentine fat-tailed mouse opossum was formerly considered a species of opossum in the family Didelphidae. It is found in the eastern foothills of the Andes in northern Argentina and southern Bolivia. Typically reach around 10-13 cm in body length, with a bushy tail adding another 12-15 cm. Its dorsal fur is gray brown to dark brown. Its ventral fur is gray-based except for the white to yellowish chest hairs. It has been distinguished from T. cinderella by its postorbital ridges. T. cinderella has well-developed postorbital ridges in both juveniles and adults that extend laterally behind the eye sockets. Only adults of T. sponsorius have fully developed postorbital ridges, and these do not extend laterally behind the eye sockets. However, mitochondrial DNA sequence analysis does not support the population being distinct from T. cinderella.
Agricola's gracile opossum is a species of opossum in the family Didelphidae endemic to eastern Brazil. Its habitat is the caatinga and cerrado. While its conservation status has not been determined, expansion of agricultural activities is leading to loss of some of its habitat. There are several protected areas in the species' range but it has not been collected from these areas. The species is named after Brazilian physician Ernani Agricola.
The chacoan gracile opossum is a species of opossum in the family Didelphidae. It is native to Argentina, Brazil and Paraguay. Its habitat is seasonally flooded grasslands and forests in and near the Gran Chaco.
The Guahiba gracile opossum is a species of opossum in the family Didelphidae. It is endemic to southern Brazil, where it is known only from three islands, Guahiba, São Lourenço, and Taquara, in the state of Rio Grande do Sul. The poorly studied species is presumed to inhabit subtropical forests, and thus to be threatened by deforestation.
The Unduavi gracile opossum is a species of opossum in the family Didelphidae. It is native to northern Bolivia, where it has been found in seasonally flooded grassland. Some of the specimens recognized by Voss et al. as belonging to this species were previously classified as the unduaviensis or buenavistae subspecies of Gracilinanus agilis.
Cryptonanus is a genus of opossums from South America. It includes five species found from Bolivia to Uruguay and eastern Brazil, one of which is now extinct. Although the first species were discovered in 1931, the genus was not recognized as distinct from Gracilinanus until 2005. It includes small opossums with generally grayish, sometimes reddish, fur that are mainly distinguished from other opossums by characters of the skull.
