| Josephoartigasia monesi Temporal range: Pliocene to Early Pleistocene 4–2 Ma |
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|---|---|
| Josephoartigasia monesi reconstruction | |
| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Mammalia |
| Order: | Rodentia |
| Family: | Dinomyidae |
| Genus: | †Josephoartigasia |
| Species: | †J. monesi Rinderknecht & Blanco, 2008 |
| Binomial name | |
| Josephoartigasia monesiAuto Rinderknecht & Blanco, 2008 |
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Josephoartigasia monesi, an extinct species of South American caviomorph rodent, is the largest rodent known, and lived approximately 4 to 2 million years ago during the Pliocene to early Pleistocene.[1][2] The species may have weighed 1,000 kg (2,200 lb), considerably larger than its closest living relative, the pacarana.[1] The rodent may have lived in an estuarine environment or a delta system with forest communities,[1] and may have eaten soft vegetation.[3]
J. monesi is known from an almost complete skull, which was recovered from the San José Formation on the coast of Río de la Plata in Uruguay.[1] Discovered in 1987, but not scientifically described until 2008, the specimen is preserved in Uruguay's National History and Anthropology Museum.[4] The species is one of two in the Josephoartigasia genus, the other being J. magna.[1] J. monesi is sometimes called the giant pacarana, after its closest living relative, the pacarana (Dinomys branickii) in the family Dinomyidae.[1]
The skull of the holotype is 53 cm (21 in) long, and the remaining incisor is more than 30 cm (12 in) in length. The total estimated body length is 3 m (10 ft), with a height of 1.5 m (5 ft).
By comparing the skull with various extant species of rodent, the authors of the original paper estimated a mass between 468 kg (1,030 lb) and 2,586 kg (5,700 lb), with a median estimate of 1,211 kg (2,670 lb).[1] A later researcher revisited the numbers and came up with a more conservative estimate of 350 kg (770 lb) to 1,534 kg (3,380 lb), with a median of 900 kg (2,000 lb).[5] (Compare 800 to 1,400 kg (1,800 to 3,100 lb) for an adult Black Rhinoceros.}
There is no dispute that J. monesi replaces Phoberomys pattersoni, a related and somewhat older species that lived in Venezuela during the Late Miocene, as the largest rodent. However, size comparisons are difficult because previous estimates of 400 kg (880 lb) and 700 kg (1,500 lb) for P. pattersoni were based on forelimb and hindlimb elements, which are not present in the J. monesi specimen.[1]