Eocardia is an extinct genus of rodent from the Early to Middle Miocene of Argentina and Chile, South America. The 30 centimetres long creature was related to guinea pigs and the capybara.

The guinea pig, also known as the domestic guinea pig, cavy or domestic cavy, is a species of rodent. It belongs to the genus Cavia, family Caviidae, and its closest wild relatives include the Montane