Caviomorphs

Caviomorphs are a diverse clade of rodents that originated in South America and now include many of the Neotropics’ most recognizable species. They form a major lineage within the Hystricognathi and encompass several living groups, such as capybaras, guinea pigs, chinchillas and viscachas, agoutis and acouchis, pacas, spiny rats, New World porcupines, and the nutria. Their dental and cranial traits reflect adaptation to herbivory and a variety of habitats.

Historically, caviomorphs diversified across South America before dispersing into Central and North America when land connections allowed, during the later Cenozoic. Today they occupy a wide range of environments from tropical forests to high Andes scrub, deserts, and wetlands. Capybaras inhabit wetlands; chinchillas prefer cool Andean habitats; many species are nocturnal or crepuscular.

Ecology and behavior vary widely among lineages. Most are herbivorous or omnivorous to some degree; some species are highly social, others solitary. Reproduction rates and growth vary; some species have rapid reproductive cycles, contributing to their resilience, while others are threatened by habitat loss, hunting, and competition with livestock.

Fossil records extend back to the Paleogene in South America, with diverse forms appearing in the Eocene. The caviomorphs’ unique features and distribution have made them important for studies of rodent evolution, biogeography, and Neotropical ecosystems.