Capybara The capybara is the largest rodent in the world. The capybara’s name comes from the native people of South America. It means "master of the grass." The scientific name of the capybara is hydrochoerus hydrochaeris, which means "water pig" in Greek. Capybaras have been in existence since the Pleistocene epoch. Their ancient ancestors were rodents that lived about sixty million years ago. The average size of a capybara is four feet in length and two feet in height. This is about the size of a sheep. Capybaras usually weigh between sixty and one hundred and forty pounds. Many people think the capybara looks like a larger version of a guinea pig. All capybaras have large f