Josephoartigasia monesi

Josephoartigasia monesi is an extinct rodent species that lived during the Pliocene to the Early Pleistocene Epoch (about 4 million years ago). This massive caviomorph rodent is related to the pacarana (a rare, slow-moving rodent found in South America). However, it is significantly larger. Josephoartigasia monesi is the largest rodent on record. It lived in South America along with the terror birds, giant sloths, and saber-toothed cats. 

Description & Size

Josephoartigasia monesi is an extinct species of giant rodents that lived between the Early Pliocene to Early Pleistocene epochs. It belonged to the genus Josephoartigasia along with another species, the Josephoartigasia manga. The genus name “Josephoartigasia” pays homage to José Artigas, a political leader and libertador of Uruguay. On the other hand, the species’ name is a reference to Álvaro Mones, who discovered many notable fossils in South America, including the first fossil in the Josephoartigasia genus. 

J. monesi holds the title for the largest rodent on record, displacing Phoberomys pattersoni, a related but older rodent species that also lived in South America. The estimated body size of this species is about 500 kg (1,102 lb) by the most conservative estimates. According to more generous estimates, J. monesi would have been about 1,211 kg (2,670 lb) on average, with a maximum weight of up to 2,586 kg (5,701 lb)

That’s about the same size as a horse. The skull of the Josephoartigasia monesi measured up to 53 cm (1.7 ft) in length. According to estimates, the body length of this rodent would have been about 3 m (9.8 ft) with a height of 1.5 m (4.9 ft).

The J. monesi had one incisor, no canines, one premolar, and three molars in either half of its jaw. Since it was a rodent, the teeth most likely grew throughout its life. The massive chisel-like incisors were most likely incredibly strong. The grinding teeth had a much smaller surface area and were less pronounced. 

Diet – What Did Josephoartigasia Monesi Eat?

The Josephoartigasia monesi had massive front teeth. Yet, despite their fearsome appearance, they were herbivorous and may have eaten soft vegetation. However, they were capable of biting through really tough materials. 

This rodent’s small molars and premolars were not good enough for grass and other types of abrasive vegetation. Hence, its diet would have consisted predominantly of soft aquatic plants and fruits. Also, since it was large, it would have been able to digest low-quality food sources such as roots and wood that smaller mammals would have been unable to digest. 

According to estimates, the bite force of this rodent would have been as high as 936 pounds. This is up to 3 times higher than the bite force of present-day tigers. Their incisors would have served a similar function to modern elephants ‘ tusks. Scientists think they used it for digging for roots and self-defense. Some theories also suggest that they used the teeth to fight over females for breeding rights. 

Habitat – When and Where Josephoartigasia monesi Lived

Paleontologists dug up the fossil of the Josephoartigasia monesi from the San José Formation in Uruguay. This giant rodent lived in this part of South America from the Pliocene to Pleistocene (4–2 Myr ago). The environment at the time was most likely an estuarine or deltaic system with forest communities.

Threats And Predators

Josephoartigasia monesi lived alongside large predators like the saber-toothed tigers, sparassodonts, and terror birds that dominated the south American continent at the time. However, given the size of this rodent, it would have been no-easy prey for any of the large predators that lived at the time. It also had massive front teeth with a powerful bone-crunching bite force that would have deterred any predators from preying on it. 

Discoveries and Fossils – Where It Was Found

The first fossil of a closely related member of the same genus was discovered in the San José formation in 1966. It was a piece of jawbone with the incisor, premolar and first two molars preserved. The enormous fossil was the first member of Josephoartigasia to be described. However, it belonged to another species called Josephoartigasia magnus.  

The Josephoartigasia monesi itself was found later. In 1987, fossil collector Sergio Viera uncovered the nearly complete skull in the Barrancas de San Gregorio formation. However, it was not fully described and named until 2008. 

Extinction – When Did It Die Out?

Josephoartigasia monesi lived in South America during the Pliocene and Pleistocene eras, between 5.3 million and 12,000 years ago. This is around the same time when the last ice age ended. Changes in climatic conditions may have contributed to the decline of this species. Competition from invasive species that migrated into South America from North America may have also led to their extinction. 

Similar Animals to The Josephoartigasia monesi

Similar animals to the Josephoartigasia monesi include: 

• Phoberomys pattersoni: this is a related but slightly older species that lived in Venezuela during the Late Miocene. It was the largest rodent on record before Josephoartigasia monesi took the spot. 
• Pacarana: Dinomys branickii is the only living member of the Dinomyidae family. It is significantly smaller than its prehistoric siblings like the Phoberomys pattersoni and Josephoartigasia monesi. 
• Josephoartigasia magna: this is the only other known member of the Josephoartigasia genus. Scientists discovered it earlier, and the description of this genus is based on the species. It lived in South America as well. 

Sources 

https://en.wikipedia.org/wiki/Josephoartigasia

https://www.nationalgeographic.com/science/article/giant-fossil-rodent-had-an-awesome-bite

https://www.livescience.com/2224-huge-rodent-bigger-bull.html

https://prehistoric-fauna.com/Josephoartigasia-monesi