Now that is one big-ass rodent

From a previously unexamined skull, scientists have established that 8 foot long, 1,500 pound rats roamed South America 4 million years ago:

Imagine a rodent that weighed a ton and was as big as a bull. Uruguayan scientists say they have uncovered fossil evidence of the biggest species of rodent ever found, one that scurried across wooded areas of South America about 4 million years ago, when the continent was not connected to North America.

...

Its huge skull, more than 20 inches long, suggested a beast more than eight feet long and weighing between 1,700 and 3,000 pounds.

Although British newspapers variously described it as a mouse or a rat, researchers say the animal, named Josephoartigasia monesi, actually was more closely related to a guinea pig or porcupine.

"These are totally different from the rats and mice we're accustomed to," said Bruce Patterson, the curator of mammals at the Field Museum in Chicago, adding that it was the biggest rodent he had ever heard of.

An artist's rendering showed a creature that looked like a cross between a hippopotamus and guinea pig.

I work with rats all day, and they are not generally cooperative animals. I can only guess what these bastards would be like. At least they say in the paper that they probably ate aquatic plants.

This would distinguish them from your typical NY sewer rat, a species that appears to exist on absolutely no food at all, breeds by binary fission like yeast, and that thirsts for blood just for the fun of it.

The findings are published in Proceedings of the Royal Society B.