| Josephoartigasia | |
|---|---|
| |
| J. monesi skull, scale = 10 cm (3.9 in) | |
Scientific classification 
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| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Mammalia |
| Order: | Rodentia |
| Family: | Dinomyidae |
| Genus: | †Josephoartigasia Francis and Mones, 1966 |
| Type species | |
| †Artigasia magna | |
| Species | |
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Josephoartigasia is an extinct genus of enormous dinomyid rodent from the Early Pliocene to Early Pleistocene of Uruguay. The only living member of Dinomyidae 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 practically complete skull. Both are reported from the San José Member of the Raigón Formation by the Barrancas de San Gregorio along the shores of Kiyú beach.
The skull of J. monesi measures 53 cm (1 ft 9 in), similar to a beef cow skull, equating to a full body length of 262.8 cm (8 ft 7 in)—though this is likely an overestimate—and a weight of about 480–500 kg (1,060–1,100 lb). 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 60 kg (130 lb). J. monesi also had a massive bite force of approximately 1,400 N (310 lbf) at the incisors (on par with large carnivores) and 5,000 N (1,100 lbf) 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.
Josephoartigasia lived in a forested estuarine environment, alongside toxodontids, ground sloths, glyptodonts, scimitar-toothed cats, terror birds, and thylacosmilids. Like other giant extinct rodents, Josephoartigasia predominantly ate C3 plants, such as leaves or fruits, though the extreme bite force of J. monesi would have permitted it to consume a wide variety of different plants if necessary.