Capybara
The capybara ("Hydrochoerus hydrochaeris") is a mammal native to South America. It is the largest living rodent in the world. Also called chigüire, chigüiro (in Colombia and Venezuela) and carpincho, it is a member of the genus "Hydrochoerus", of which the only other extant member is the lesser capybara ("Hydrochoerus isthmius"). Its close relatives include guinea pigs and rock cavies, and it is more distantly related to the agouti, the chinchilla, and the coypu. The capybara inhabits savannas and dense forests and lives near bodies of water. It is a highly social species and can be found in groups as large as 100 individuals, but usually lives in groups of 10–20 individuals. The capybara is not a threatened species but it is hunted for its meat and hide and also for grease from its thick fatty skin, which is used in the pharmaceutical trade.
Mara (mammal)
The maras ("Dolichotis") are a genus of the cavy family of rodents. They are the sole extant representatives of the subfamily Dolichotinae. These large relatives of guinea pigs are common in the Patagonian steppes of Argentina, but also live in Paraguay and elsewhere in South America. Maras are the fourth-largest rodent in the world, after capybaras, beavers, and porcupines, reaching about in height.