“Capybaras belong to the cavy family, Caviidae, alongside guinea pigs, maras, and rock cavies, their closest living relatives. Their ancestors are thought to have rafted from Africa to South America around 40 million years ago. Extinct capybara relatives were even larger, and some lived in North America during the Ice Age.”
The capybara may look like a one-of-a-kind animal, but it’s part of a remarkable family story. From tiny ancestors that crossed an ocean to giant extinct cousins that roamed two continents, capybara evolution is full of surprises. This guide explains where capybaras sit in the tree of life and how they came to be the world’s largest living rodent.
Capybara Classification
| Rank | Name |
|---|---|
| Kingdom | Animalia |
| Class | Mammalia |
| Order | Rodentia |
| Suborder | Hystricomorpha |
| Family | Caviidae (cavies) |
| Subfamily | Hydrochoerinae |
| Genus | Hydrochoerus |
| Species | Hydrochoerus hydrochaeris (greater capybara) and Hydrochoerus isthmius (lesser capybara) |
The genus name Hydrochoerus comes from Greek words meaning “water pig,” a nod to the capybara’s semi-aquatic life and barrel-shaped body.
Capybaras Are Cavies
For many years, capybaras were placed in their own family, Hydrochoeridae. But genetic studies showed they are nested within the cavy family, most closely related to the rock cavies (Kerodon) of Brazil. Today, many scientists place capybaras and rock cavies together in the subfamily Hydrochoerinae within Caviidae.
That makes the capybara a true cousin of the domestic guinea pig. See capybara vs guinea pig and are capybaras rodents.
The Capybara’s Closest Relatives
- Rock cavies: agile rodents that live in rocky outcrops in northeastern Brazil.
- Guinea pigs and wild cavies: small grazers of South American grasslands and mountains.
- Maras (Patagonian hares): long-legged cavies that look like a cross between a rabbit and a small deer.
- Yellow-toothed cavies and others: small cavy species across South America.
More distant relatives in the same broad group include chinchillas, degus, porcupines, nutria, agoutis, and pacas. See types of rodents.
Two Capybara Species
Greater Capybara
The familiar capybara, found across most of South America east of the Andes. Adults typically weigh 77 to 146 pounds. See capybara facts.
Lesser Capybara
Smaller and less studied, the lesser capybara lives in Panama, northwestern Colombia, and western Venezuela. It was once considered a subspecies of the greater capybara but is now widely recognized as a separate species. See where capybaras live.
Crossing an Ocean
The capybara’s lineage belongs to a group called caviomorph rodents, which appear in South American fossils around 40 million years ago. At that time, South America was an island continent, and the Atlantic Ocean was much narrower than today. The closest relatives of caviomorphs live in Africa, so the leading explanation is that a small group of ancestral rodents crossed from Africa on floating rafts of vegetation. Once there, they diversified into dozens of families. Read more in rodent evolution.
Giant Extinct Capybaras
Today’s capybara is the largest living rodent, but its extinct relatives were bigger still. Fossils of capybara relatives from South America show that the group had diverse, sometimes very large, members over the past several million years.
Neochoerus, an extinct capybara relative, was larger than modern capybaras. When the Isthmus of Panama connected North and South America a few million years ago, capybara relatives moved north as part of the Great American Biotic Interchange. Neochoerus fossils have been found in North America, including in Florida, showing that giant capybara relatives once lived in what is now the United States during the Ice Age.
Other extinct South American rodents, not direct capybara ancestors but distant cousins, grew far larger, including Josephoartigasia, which may have rivaled a bull in size. See our rodent size comparison.
How Capybaras Adapted
Over millions of years, the capybara lineage became specialized for a semi-aquatic grazing life:
- Eyes, ears, and nostrils high on the head for seeing and breathing while mostly submerged
- Partially webbed feet for swimming
- Ever-growing cheek teeth with complex ridges for grinding tough grasses
- A large cecum for fermenting fibrous plants
- Large body size, which helps with digestion and deters some predators
- Complex social behavior for group vigilance
See capybara anatomy and capybara swimming.
Why Did Capybaras Get So Big?
Large body size is common among grazing mammals. A bigger gut can process more fibrous grass efficiently, and larger animals lose heat more slowly and are harder for many predators to kill. For capybaras, size combined with water-based escape and group living proved a successful strategy in South America’s wetlands.
Capybaras vs Hippos: Convergent Evolution
Capybaras and hippos aren’t related, but their similar lifestyles led to similar features, a process called convergent evolution. Both have eyes and nostrils on top of their heads and spend much of their day in water. See capybara vs hippo.
Capybara Names Around South America
The English word “capybara” comes from the Tupi language of Brazil. In Portuguese, the animal is called capivara, and in Spanish-speaking countries it has many regional names, including chigüire or chigüiro in Venezuela and Colombia, carpincho in Argentina, Uruguay, and Paraguay, and ronsoco in parts of Peru. Many towns and rivers in Brazil, such as Capivari, are named after the capybara, showing how deeply the animal is woven into the region’s history. Learn more in capybaras in culture.
Capybara Subspecies and Variation
Some scientists have described regional forms of the greater capybara, differing slightly in size and skull features across its huge range. Capybaras from the southern part of the range, in Argentina and Uruguay, tend to be larger than those from northern South America. Classification at this level is still debated, and more genetic research is needed. Rare color variants also occur, including the occasional very pale or albino capybara. See albino capybaras.
What the Fossil Record Tells Us
Fossils of capybara relatives are especially common in Argentina, Uruguay, and Brazil, often preserved in river and wetland deposits, which matches the group’s long association with water. Their distinctive cheek teeth, made of many plate-like layers, are easy to recognize even as isolated fossils. By comparing teeth from different time periods, scientists have traced how the group adapted to eating tougher grasses as South America’s grasslands expanded over the last several million years.
Frequently Asked Questions
What family does the capybara belong to?
The cavy family, Caviidae, which also includes guinea pigs.
What is the capybara’s closest living relative?
Rock cavies of Brazil are considered the capybara’s closest living relatives.
Were there giant capybaras?
Yes. Extinct capybara relatives such as Neochoerus were larger than today’s capybaras.
Did capybaras ever live in North America?
Extinct relatives did, during the Ice Age, after crossing the Panama land bridge.