Caviidae
Caviidae, the cavy family, is composed of rodents native to South America and includes the domestic guinea pig, wild cavies, and the largest living rodent, the capybara. They are found across South America in open areas from moist savanna to thorn forests or scrub desert. This family of rodents has fewer members than most other rodent families, with 19 species in 6 genera in 3 subfamilies.
Phoberomys pattersoni
An almost complete skeleton was discovered in the Urumaco Formation at Urumaco, Venezuela, in 2000. The new species was later classified with the name "Phoberomys pattersoni" in honor of palaeontologist Brian Patterson. From the fossil, researchers have been able to reconstruct its size and probable lifestyle. It was long, with a tail at , and probably weighed between ), making it for some years the largest known rodent for which good size and weight estimates were possible. Its congener "Phoberomys insolita" was a bit larger still, but it is not known from any reasonably complete remains, thus its size cannot be estimated more precisely.