Josephoartigasia

Josephoartigasia is an extinct genus of enormous dinomyid rodent from the Early Pliocene to Early Pleistocene of Uruguay. Its closest living relative is the pacarana. Josephoartigasia is named after Uruguayan national hero José Artigas. It contains two species: J. magna, described in 1966 based on a left mandible, and J. monesi, described in 2008 based on a nearly complete skull. Both are reported from the San José Member of the Raigón Formation by the Barrancas de San Gregorio along Kiyú beach.

The skull of J. monesi measures , similar to a beef cow skull, equating to a full body length of —though this is likely an overestimate—and a weight of about . This makes J. monesi the biggest rodent ever discovered. It was much larger than J. magna, giant hutia or the largest living rodent, the capybara, which averages . J. monesi also had a massive bite force of approximately at the incisors (on par with large carnivores) and at the third molar (rivaling large crocodilians). Its skull was heavily reinforced to withstand high stresses far exceeding what bite force alone could exert, so it could have been using its teeth to crack nuts, excavate large burrows, dig up roots, or self defense against predators.