Imagine an animal that was as big as a bull and looked like a cross between a hippopotamus and a guinea pig. That's what scientists believe, "Josephoartigasia Monesi" (we can't pronounce it either) looked like - except that this was no bull, but a mere rodent in the pre-historic era. Makes you wonder how big the bull was during that time.

A fossil collector in Uruguay, South America found the skull of this enormous pre-historic creature about twenty years ago. He donated it to Uruguay's National History and Anthropology Museum, where it set in a box until recently.

While the skull was as big as a cow's, it's shape and the huge incisors (the two sharp teeth on the top and bottom jaw) convinced scientists that the creature was a rodent, similar to a porcupine or guinea pig. An examination of its teeth revealed that the creature was an herbivore (ate plants).

Scientists believe that rodents in the pre-historic era became really big because South America was still an island, and there was no competition in the eco system from animals like the hippos and rhinos. When the North and South American continents linked together, about three million years ago, the North American animals overwhelmed these rodents and they became extinct.

The closest relative to this creature is the Pacarana, a sharp-clawed, 30-pound rodent that lives near the Andes Mountains. This is the largest rodent alive today, but there are not too many left because, unlike rats, these animals do not produce too many babies. Additionally, they are considered a yummy treat by the local people and killed for food.

This is a very important discovery, providing great insight into how big animals got in the pre-historic era and how they have evolved over the years.

The picture shows an artist's rendition of how big just the skull of the rodent was in comparison with an entire rodent in today's world.