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York scientists say the largest rodent ever (artist's impression shown) had giant incisors that it used like elephant tusks, based on skull analysis

The largest rodent ever to have lived may have used its front teeth just like an elephant uses its tusks, according to a new study. 

The rodent would have been the size of a buffalo, with the largest incisors of any rodent ever known to have existed.

Josephoartigasia monesi, a rodent closely related to guinea pigs, lived in South America approximately three million years ago.

It is the largest fossil rodent ever found, with an estimated body mass of 2,200lbs (1,000kg), and it was similar in size to a buffalo.

The study was led by scientists at the University of York and The Hull York Medical School.

Dr Philip Cox, of the Centre for Anatomical and Human Sciences, a joint research centre of the University's Department of Archaeology and HYMS, used computer modelling to estimate how powerful the bite of Josephoartigasia could be - comparable to that of a tiger.

Speaking to MailOnline, he said the only fossil they have is a skull that is around 20 inches (50cm) in length - which makes it the largest rodent ever.

But using it was enough to work out how large and powerful the teeth of the rodent would have been.

'Like all rodents it had just a single pair of incisors in the upper and lower jaw, and these are large curved structures that grow throughout life,' he said.

'Like most rodents it was herbivorous, and the environment it lived in was something like an estuary or water land, at the margins of water, eating maybe aquatic plant material or something.' 

He thinks the incisors were likely used either to dig into the ground to get at roots to eat, or to defend the animal.

The entire circular length of the incisors was likely about 10 inches (25cm), with only a small part of that actually protruding from the mouth.

The rest pushed back into the skull.

Josephoartigasia monesi, a rodent closely related to guinea pigs, lived in South America approximately three million years ago. It is the largest fossil rodent ever found, with an estimated body mass of 2,200lbs (1,000kg), and was similar in size to a buffalo (shown in this comparison)

Dr Philip Cox, of the Centre for Anatomical and Human Sciences, a joint research centre of the University's Department of Archaeology and HYMS, used computer modelling to estimate how powerful the bite of Josephoartigasia could be from a limited skull of the animal

Dr Cox found that, although the bite forces were very large - around 1,400 Newtons, similar to that of a tiger - the incisors would have been able to withstand almost three times that force, based on earlier estimates by a team who first described the fossil in 2008.

This could have been a 'safety' measure to survive some of the rodent's more strenuous tasks. 

He said in a separate statement: '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.'

The research, which is published in the Journal of Anatomy, involved CT scanning the Josephoartigasia monesi specimen and making 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.

Dr Cox found that, although the bite forces were very large - around 1,400 Newtons, similar to that of a tiger - the incisors would have been able to withstand almost three times that force, based on earlier estimates by a team who first described the fossil of the skull (shown) in 2008