Long after the dinosaurs were gone, giant guinea pigs roamed the earth. Fossil records of these beasts are mostly found in South America. The first nearly complete skeleton was found in 2000 in Urumaco, Venezuela.

At 1,500 pounds (680 kilograms), these buffalo-sized rodents were the second largest species in their genus. The biggest would be Josephoartigasia monesi, fossils of which were discovered in 2008. These two species were some of the largest mammals, second only to diprotodontian marsupials.

These caviomorphs are related to the capybara, chinchillas, beavers, squirrels, guinea pigs, rats, and mice.

You can see an illustration of them here.