Is it a cat? Is it a dog? Is it a hamster? These are just some of the questions Melanie Typaldos and her daughter Coral have to answer when they are seen with their pet. In fact, Caplin Rous is a capybara, the largest species of rodent in the world and closely related to the guinea pig. Capybara Caplin lives in Texas and he is the most famous capybara in the world. The capybara is the largest living rodent in the world.