Josephoartigasia monesi, truly was a rodent of unusual size. The distant relative of the guinea pig weighed about 2,000 pounds and was the size of a buffalo. The animals lived in South America, primarily in what is now Venezuela from 4 million years ago until about 2 million years ago.

New research, led by scientists at the University of York and The Hull York Medical School (HYMS), shows that the fearsome rodent may have used its large front teeth in much the same way that an elephant uses its tusks.

The animals are believed to have lived in a delta system with forest communities or an estuarine environment. Despite its size and potentially lethal teeth the animal is believed to have been an herbivore. It’s small molars, good for grass and vegetation, simply wouldn’t have helped it much with meat. J. Monesi likely fed on aquatic plants, fruits and food resources such as wood that were ignored by smaller species.

Dr. Philip Cox, of the Centre for Anatomical and Human Sciences, used computer modeling to see just how powerful the animals bite would have been.

Cox found that the bit force was very large, similar to that of a tiger. However, the animals incisors would have had to withstand an impact of three times that force.

That finding was based on earlier estimates by his co-authors, Dr Andres Rinderknecht, of The Museo Nacional de Historia Natural, Montevideo, and Dr Ernesto Blanco, of Facultad de Ciencias, Instituto de Fisica, Montevideo, who first described the fossil in 2008.

“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. This is very similar to how a modern day elephant uses its tusks,” said Dr. Cox in a statement.

Elephants, which are also large herbivores, can use their tusts as defensive weapons. This is handy because large, slow herbivores that cannot climb, fly or swim very well are always attractive to large carnivores. The tusks can also be used for moving objects and for digging.

Elephant tusks begin as incisors just like J.monesi. The elephant incisors curl up as they become long, but J.monesi would have faced the same challenge as all rodents. Rodents are characterized, in part, by a single pair of continuously growing incisors in each of the upper and lower jaws. These teeth must be continually filed down, usually by gnawing or chewing and that filing leaves them very sharp.

The latest research, which is published in the Journal of Anatomy, involved CT scanning the Josephoartigasia monesi specimen and using computer modeling to create a virtual reconstruction of its skull. This was then subjected to finite element analysis, an engineering technique that predicts stress and strain in a complex geometric object.

J. monesi was first discovered in 1987, when a nearly complete scull was found in the San José Formation on the coast of Río de la Plata in Uruguay. However, it was not described scientifically until 2008. The animal was named after paleontologist Alvaro Mones, who did a study on the creature from lesser remains in 1966.