Only a single fossilised skull has been found belonging to this 1,000kg South American rodent, known as Josephoartigasia monesi. Unearthed in Uruguay in 2007, the animal lived in the Pliocene period - a warm era when large mammals were relatively abundant, including the first mammoths. It remains the largest rodent ever discovered.
Researchers believe the front teeth must have been used for tasks that required extra muscles, like the neck, as well as the biting action of the jaw muscles themselves. "We concluded that Josephoartigasia must have used its incisors for activities other than biting, such as digging in the ground for food, or defending itself from predators," said an anatomist. "This is very similar to how a modern-day elephant uses its tusks."
|the extinct rodent (right) pictured in comparison with a human and a pacarana, its closest living relative|