Josephoartigasia monesi, a rodent closely related to guinea pigs, lived in South America around 3 million years ago. With an estimated body mass of 1000 kg it was similar in size to a buffalo! An almost complete skull (the largest fossil rodent ever found), unearthed from San José Formation in Uruguay, is preserved in the National History and Anthropology Museum of Uruguay. The animal lived during the Pliocene period, an era marked by an abundance of large animals including the first mammoths.
Scientists found that although the rodent’s bite forces were very large — around 1400 Newtons, similar to that of a tiger, its incisors would have been able to withstand almost three times that force. They concluded that it must have used its incisors for other activities too, such as digging in the ground for food or defending itself from predators, similar to how a modern-day elephant uses its tusks.