Caviomorpha is the rodent infraorder or parvorder that unites all New World hystricognaths. It is supported by both fossil and molecular evidence. The Caviomorpha was for a time considered to be a separate order outside the Rodentia, but is now accepted as a genuine part of the rodents. Caviomorphs include the extinct Heptaxodontidae, the extinct Josephoartigasia monesi and extant families of chinchilla rats, hutias, guinea pigs and the capybara, chinchillas and viscachas, tuco-tucos, agoutis, pacas, pacaranas, spiny rats, New World porcupines, coypu and octodonts.
Abrocoma is a genus of abrocomid rodents found in the Andes of South America, from southern Peru to central Chile. The genus contains eight species, most of which are found in isolated mountain ranges in northwestern Argentina. The oldest fossil record for the Caviomorpha appears at the late Eocene-Early Oligocene transition. The Abrocoma has an interesting body structure for example within its own head it has a sac that contains a liquid that is not named by Janet K. Braun and Michael A. Mares(894). They also have feet that are padded whiched helped to completely say with certainty that it is a rock dweller but also a rock climber.(896).
The blesmols, also known as mole-rats, or African mole-rats, are burrowing rodents of the family Bathyergidae. They represent a distinct evolution of a subterranean life among rodents much like the pocket gophers of North America, the tuco-tucos in South America, or the Spalacidae from Eurasia.
The term Hystricomorpha has had many definitions throughout its history. In the broadest sense, it refers to any rodent with a hystricomorphous zygomasseteric system. This includes the Hystricognathi, Ctenodactylidae, Anomaluridae, and Pedetidae. Molecular and morphological results suggest the inclusion of the Anomaluridae and Pedetidae in Hystricomorpha may be suspect. Based on Carleton & Musser 2005, these two families are discussed here as representing a distinct suborder Anomaluromorpha.
The Asháninka arboreal chinchilla rat is a large species of chinchilla rats from the Andes of far northern Cusco in Peru. It was first scientifically described in 1999.
Cuscomys is a genus of rodents found in the Andes of Cusco in southern Peru. These relatively large chinchilla rats are dark grey with a distinct white line running from the crown to the nose. The genus was coined in 1999 when C. ashaninka was scientifically described, but later it was discovered that C. oblativus, a species traditionally placed in the genus Abrocoma, actually belonged in Cuscomys. They are very poorly known, as C. ashaninka only is known from the holotype, while C. oblativus usually has been considered extinct, as it was only known from remains found in 1912, buried alongside people in ancient Inca tombs at the Machu Picchu ruins. However, photos of a rodent taken at the ruins in late 2009 likely show this species. It is unclear if the Cuscomys truly are extremely rare, as they may be easily overlooked due to their remote distributions and arboreal habits.
The Machu Picchu arboreal chinchilla rat is a large species of South American chinchilla rats, known from skeletal remains found by members of the Peruvian Expedition of 1912. The animals were buried alongside people in ancient Inca tombs at Machu Picchu in Peru. It was considered extinct by the IUCN in 2008, but conservation status was changed to data deficient in 2016. Photos of a rodent taken at Machu Picchu in late 2009 likely show this species, a finding apparently confirmed in 2014.
The toros or brush-tailed rats, genus Isothrix, are a group of spiny rats found in tropical South America, particularly in the Amazon Basin.
Bennett's chinchilla rat is a species of chinchilla rat in the family Abrocomidae. It is found only in Chile where its habitat is Mediterranean-type scrub on the western side of the Andes. The IUCN has assessed its conservation status as being of "least concern".
The ashy chinchilla rat is a species of chinchilla rats in the family Abrocomidae found in Argentina, Bolivia, Chile, and Peru.
Budin's chinchilla rat is a species of chinchilla rat in the family Abrocomidae. Found only in Argentina, the categorization of this species was based on analysis of four specimens which were caught among the rocks in the clefts of which it lived. It is specifically known from Otro Cerro, Catamarca Province and known to occur in rocky areas over 3,000 meters above sea level; research shows it may be confined to Sierra de Ambato in Catamarca Province and La Rioja Province. In 2002, Braun and Mares from the University of Oklahoma examined this specimen and confirmed it to be a separate species. Not enough is known about this species for the IUCN to assess its conservation status.
The Famatina chinchilla rat is a species of chinchilla rats in the family Abrocomidae found only in Argentina.
The Sierra del Tontal chinchilla rat is a species of chinchilla rat. Found only in Argentina, this species was once thought to be part of Abrocoma cinerea. In 2002, Braun and Mares from the University of Oklahoma confirmed it to be a separate species.
The Uspallata chinchilla rat is a species of chinchilla rat in the family Abrocomidae native to Argentina. This species was identified in 2002, by Braun and Mares from the University of Oklahoma. Only a single specimen has been examined.
The Punta de Vacas chinchilla rat, also known as the Mendozan chinchilla rat, is a species of chinchilla rats in the family Abrocomidae. Found only in Argentina, this species was once thought to be part of Abrocoma cinerea. In 2002, Braun and Mares from the University of Oklahoma confirmed it to be a separate species.
Rodents are mammals of the order Rodentia, which are characterized by a single pair of continuously growing incisors in each of the upper and lower jaws. About 40% of all mammal species are rodents. They are native to all major land masses except for New Zealand, Antarctica, and several oceanic islands, though they have subsequently been introduced to most of these land masses by human activity.
Echimyidae is the family of neotropical spiny rats and their fossil relatives. This is the most species-rich family of hystricognath rodents. It is probably also the most ecologically diverse, with members ranging from fully arboreal to terrestrial to fossorial to semiaquatic habits. They presently exist mainly in South America; three members of the family also range into Central America, and the hutias are found in the Greater Antilles in the Caribbean. Species of the extinct subfamily Heteropsomyinae formerly lived on Cuba, Hispaniola, and Puerto Rico in the Antilles, probably until the arrival of Europeans.
