Still, a big rat

The largest rodent ever recorded might not have been as monstrous as was first suggested, a McGill scientist claims. A fossil skull belonging to the rodent Josephoartigasia monesi was uncovered in Uruguay, where the beast roamed 2-4 million years ago. It was first thought to have weighed a whopping one ton, but new estimates suggest the animal could have weighed as little as a third of that. Details appear in the journal Proceedings of the Royal Society B. Dr Virginie Millien, from McGill said the mathematical models originally used to calculate the rodent's mass from its skull probably overestimated its body size.