London, May 21 : A scientist has claimed that the largest rodent ever recorded might not have been as monstrous as was first suggested.
According to a BBC report, the rodent in question is Josephoartigasia monesi, whose fossilized skull was uncovered in Uruguay, where the beast roamed 2-4 million years ago.
Though it was first thought to have weighed a whopping one tonne, new estimates suggest the animal could have weighed as little as a third of that.
The fossil was first described in January 2008, by a team of Uruguayan researchers. They estimated the animal could have been about 15 times heavier than the largest living rodent.
The team took different parameters of the rodent's skull, fed them into the "allometric model" and obtained several body mass estimates for J. monesi.
These were between 468kg and 2,586kg - a very broad range - with an average value of 1,211kg.
Dr Virginie Millien from McGill University in Montreal, Canada, decided to recalculate these size estimates, using a larger sample of rodents for comparison and making several adjustments to the mathematical method used by the original team.
Several of the estimates she obtained were smaller than the original calculations. But, as one of the authors of the original paper on J. monesi points out, some are larger.
The mathematical models originally used to calculate the rodent's mass from its skull probably overestimated its body size, according to Dr Millien.
"The problem of extrapolation is regarded as one of the largest sources of error and is known to cause overestimation of body mass," explained Dr Millien. "J. monesi is certainly the largest rodent ever described, but, based on these calculations, its body mass may have been as low as 350kg," she added.
The giant animal's skull had lain in the Museum of Natural History in Montevideo for three years before being studied and identified as a new species.
It was recognised as a new creature by examining and comparing its teeth with other known species of Josephoartigasia.
Its incisors are extraordinarily large and researchers have speculated that the creature may have used the teeth to cut wood in a similar way to a modern-day beaver.