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.
Paucituberculata is an order of South American marsupials. Although currently represented only by the seven living species of shrew opossums, this order was formerly much more diverse, with more than 60 extinct species named from the fossil record, particularly from the late Oligocene to early Miocene epochs. The earliest paucituberculatans date to the late Paleocene. The group went through a pronounced decline in the middle Miocene epoch, which resulted in the extinction of all families of this order except for the living shrew opossums (Caenolestidae). Extinct families of Paucituberculatans include Pichipilidae, Palaeothentidae, and Abderitidae.
The family Caenolestidae contains the seven surviving species of shrew opossum: small, shrew-like marsupials that are confined to the Andes mountains of South America. The order is thought to have diverged from the ancestral marsupial line very early. They were once included in the superorder but it is now known that Ameridelphia is paraphyletic, having given rise to Australidelphia, and thus could be considered an evolutionary grade. Genetic studies indicate that they are the second most basal order of marsupials, after the didelphimorphs. As recently as 20 million years ago, at least seven genera were in South America. Today, just three genera remain. They live in inaccessible forest and grassland regions of the High Andes.
The long-nosed caenolestid, also known as the Chilean shrew opossum or long-nosed shrew opossum, is a shrew opossum that occurs in temperate forests of Argentina and southern Chile. It was first described by American zoologist Wilfred Hudson Osgood in 1924. The long-nosed caenolestid resembles Caenolestes species in morphology. It is characterized by a long, pointed snout, small eyes and ears, and one claw on a digit of each of the thin limbs. Little is known of its behavior; it appears to be terrestrial, nocturnal and omnivorous. It prefers cool, moist areas, and has a small distribution. It is classified as near threatened by the IUCN.
The dusky caenolestid, also known as Tate's shrew opossum, is a shrew opossum from South America. The dusky caenolestid is characterized by a dark brown coat with a lighter underbelly, soft and thick fur, and a loosely haired tail. A nocturnal animal, the dusky caenolestid lives on trees and feeds on insects and small invertebrates and vertebrates. It occurs in alpine and páramo forests in northern and western Colombia, Ecuador, and western Venezuela. The IUCN classifies this shrew opossum as least concern.
The bare-tailed woolly opossum is an opossum from South America. It was first described by Swedish zoologist Carl Linnaeus in 1758. The bare-tailed woolly opossum is characterized by a gray head, brown to gray coat, orange to gray underside and a partially naked tail. It is nocturnal and solitary; there is hardly any social interaction except between mother and juveniles and in mating pairs. The opossum constructs nests in tree cavities, and its litter size ranges from one to seven. Gestation lasts 25 days, and the juveniles exit the pouch after three months; weaning occurs a month later. The bare-tailed woolly opossum inhabits subtropical forests, rainforests, secondary forests, and plantations; its range extends from northern Venezuela to northeastern and southcentral Brazil. The IUCN classifies this opossum as least concern.
The brown-eared woolly opossum, also known as the western woolly opossum, is an opossum from South America. It was first described by German naturalist Ignaz von Olfers in 1818. The opossum is characterized by a brown to reddish brown coat and similarly colored limbs, yellow to orange underbelly, hairless, brown ears with a hint of pink, and a tail furred on the back for up to half of its length. The brown-eared woolly opossum is nocturnal, solitary and omnivorous. The IUCN lists it as least concern.
The black-shouldered opossum, also known as the white-eared opossum, is an opossum known from western Brazil and southeastern Peru. It was first described by Colin Campbell Sanborn, curator of Field Museum of Natural History, in 1951. The black-shouldered opossum is characterized by a gray coat, gray underbelly, and broad black stripes that extend from the forefeet, meet on the shoulders, run along the midline of the back and then split into parallel stripes that run down the hind feet. Little is known of the behavior of the black-shouldered opossum. It is nocturnal and arboreal. It is known to feed on fruits and rodents. The opossum inhabits humid forests. The IUCN classifies it as least concern.
The common shrew opossums are members of the family Caenolestidae. They are found in Colombia, Ecuador, Peru, and Venezuela. The most recently discovered species is C. sangay.
The dwarf fat-tailed mouse opossum, also known as the velvety fat-tailed opossum is an opossum species from South America. It is endemic to Brazil, where it is found in cerrado and caatinga habitats. Its head-and-body length is about 141-212 mm, and its tail length is about 73-85 mm. Its diet is 44% arthropods; 75% of its diet consists of animals and animal products. Its ventral fur is entirely gray-based. Its hind foot is less than 14 mm, which is short for the genus.
Derby's woolly opossum, or the Central American woolly opossum, is an opossum found in deciduous and moist evergreen forests of Central America, from southern Mexico to western Ecuador and Colombia. It was first described by English naturalist George Robert Waterhouse, and named in honor of Edward Smith-Stanley, 13th Earl of Derby. Derby's woolly opossum is the largest in its genus, with a total length of 60 to 70 centimetres and weight between 200 and 400 grams. The coat is brown and the underside white-buff to golden-brown. The opossum is nocturnal, arboreal (tree-living) and solitary. Diet consists of fruits, nectar, small invertebrates and vertebrates. The time when breeding takes place varies geographically. The litter size ranges from one to six. The IUCN classifies this opossum as least concern.
The white-bellied fat-tailed mouse opossum is a species of opossum in the family Didelphidae. It is found in Argentina, Bolivia, Chile and Peru.
The northern caenolestid, also known as the blackish shrew opossum, is a shrew opossum found in Colombia and Ecuador. It is listed as Vulnerable by the IUCN.
The Incan caenolestid, also known as the Incan shrew opossum or Peruvian caenolestid, is a caenolestid found in the southern Peruvian Andes. It was first described by English zoologist Oldfield Thomas in 1917. The head-and-body length ranges from 9 to 11.5 centimetres, and the weight is between 25 and 32 grams. It is brown on the back, and lighter on the underside. Little is known about the behaviour of the Incan caenolestid; it appears to be terrestrial and nocturnal. It feeds on small invertebrates and insects. This caenolestid inhabits elfin and secondary forests. The IUCN classifies it as least concern.
The Andean caenolestid, also known as the Andean shrew opossum or Condor caenolestid, is a shrew opossum known only from Cordillera del Cóndor (Ecuador), its type locality. It was first described by zoologists Bruce D. Patterson and Luis Albuja in 1996. It is the largest caenolestid. The IUCN classifies it as vulnerable. As of 2015, the population is estimated at less than 1,000.
The deltaic four-eyed opossum or delta opossum is a species of opossum found in the Orinoco River delta region of Venezuela, South America, first described in 2006. It inhabits perennially flooded swamp forest or seasonally flooded marsh forest of the adjacent deltas of the Orinoco and nearby rivers. Its dorsal fur is gray. Its ventral fur is cream-colored, but is restricted by the hairs on the sides, which are gray at the base. Its ears are colored only along the margins. The spots above its eyes are small. The spots behind its ears are small and inconspicuous.
Christian Miguel Pinto Baez, often stated as C. Miguel Pinto or Miguel Pinto, is an Ecuadorian zoologist noted for his research work on rodents, small carnivora, and bats from the Neotropics and their parasites. He worked as a research scientist at the Department of Mammalogy of the American Museum of Natural History until he was banned from the Smithsonian because of sexual harassment findings, and as of November 2016, held a research position at the National Polytechnic School in Quito, Ecuador.
The eastern caenolestid is a shrew opossum found on the eastern slopes of the Andes in southern Ecuador.
