Giant rat that once roamed the earth - Times Online: "The fossilised skull of a rat the size of a car has been unearthed. The creature lived about four million years ago, weighed about a tonne and ate mostly soft vegetation. It was so big that it probably spent much of its life semi-submerged in water, like a hippo, to reduce the stresses caused by its size.
Palaeontologists found the skull in rock deposits in Uruguay. It is believed to date back two to four million years to a time when giant wildlife was commonplace in South America."