Chinchillas are rodents, and their closest living relatives are viscachas, rabbit-like animals native to South America. Together, chinchillas and viscachas make up the family Chinchillidae. Beyond that immediate family, chinchillas belong to a larger group of South American rodents that includes guinea pigs, capybaras, porcupines, and degus.
The Chinchilla Family: Chinchillidae
The family Chinchillidae contains three genera and a handful of species, all native to South America. There are two living species of chinchilla: the long-tailed chinchilla and the short-tailed chinchilla. The long-tailed chinchilla is the species kept as a pet. Short-tailed chinchillas are critically endangered, with populations declining by at least 80 percent in recent decades due to hunting and habitat loss. They may be functionally extinct in the wild.
Sharing the family are two genera of viscachas. Mountain viscachas (genus Lagidium) include three species that live in rocky Andean terrain, much like chinchillas. Plains viscachas (genus Lagostomus) are stockier, ground-dwelling animals that dig extensive burrow systems in the lowland grasslands of Argentina, Bolivia, and Paraguay. If you’ve ever seen a photo of a viscacha, you probably noticed the resemblance to a chinchilla: large ears, dense fur, and a similar rounded body shape. That’s no coincidence. They’re each other’s closest relatives.
The Broader Group: South American Rodents
Zoom out one level and chinchillas belong to a group called the caviomorphs, a collection of rodents found exclusively in the Americas. This group is ancient. Its fossil record stretches back to the Eocene epoch, roughly 40 million years ago. Early ancestors of the chinchilla family appeared during the late Eocene to early Oligocene, around 34 to 37 million years ago, when stem chinchillids like Eoviscaccia first show up in the fossil record.
The caviomorphs include a surprisingly wide range of familiar animals:
- Guinea pigs (family Caviidae), probably the most well-known relative after viscachas
- Capybaras, the world’s largest living rodent, also in the Caviidae family
- Degus, small Chilean rodents sometimes kept as pets
- Porcupines (New World species in the family Erethizontidae)
- Agoutis and pacas, large ground-dwelling rodents of Central and South America
- Nutria (coypu), the semi-aquatic rodent now invasive in parts of North America and Europe
All caviomorphs share a distinctive jaw structure. The name “hystricognath” refers to the way the lower jaw is shaped, with a particular angle to the bone that sets them apart from other rodent groups like mice and squirrels. They also share a pattern of ever-growing cheek teeth adapted for grinding tough plant material. In chinchillas and their relatives, the enamel patterns on these teeth reflect a diet of dry, fibrous vegetation, the kind found in arid and mountainous habitats.
Why Chinchillas Look Like Rabbits but Aren’t
People often assume chinchillas are related to rabbits because of the large ears, soft fur, and similar size. Rabbits aren’t rodents at all. They belong to an entirely separate order called Lagomorpha. The resemblance is a case of convergent evolution: both groups developed similar traits because they occupy similar ecological roles as small, herbivorous prey animals. One easy way to tell the difference is teeth. Rabbits have a second pair of small upper incisors behind the front ones. Rodents, including chinchillas, have only a single pair.
Life in the Andes
Wild chinchillas live in the Andes Mountains of northern Chile, at elevations between 9,800 and 16,400 feet. They shelter in rock crevices and come out to feed on grasses, seeds, and other tough vegetation. This harsh, high-altitude environment shaped many of the traits chinchillas are known for. Their famously dense fur (around 60 hairs per follicle, compared to one in humans) evolved as insulation against freezing mountain temperatures, not as a luxury commodity, though it was tragically treated as one by the fur trade that nearly wiped them out.
Their relatives occupy similar niches. Mountain viscachas live in the same rocky Andean terrain, sometimes at overlapping elevations. Plains viscachas moved into lower grasslands and adapted to a burrowing lifestyle, developing stronger incisors suited for digging. Despite living in different habitats, all members of the Chinchillidae family are social, herbivorous, and primarily active at dawn and dusk.
How Chinchillas Fit Into the Rodent Family Tree
Rodents are the largest order of mammals, with over 2,000 species. Chinchillas sit within a specific branch of this tree. The full classification runs from broad to narrow: order Rodentia, suborder Hystricomorpha, infraorder Hystricognathi, parvorder Caviomorpha, and finally family Chinchillidae. Each level narrows the circle of relatives.
At the suborder level (Hystricomorpha), chinchillas are connected to Old World porcupines, African mole-rats, and other rodents with the same distinctive skull structure. At the parvorder level (Caviomorpha), the group narrows to only New World species: guinea pigs, capybaras, degus, agoutis, and the rest of the South American radiation. At the family level, only chinchillas and viscachas remain. So the answer to “what are chinchillas related to” depends on how far back you want to go. Their siblings are viscachas. Their cousins are guinea pigs and capybaras. Their distant relatives include every rodent on Earth.