'A Guinea Pig the Size of a Horse'

'Science,' Carin L. Cain

An artist's reconstruction of Phoberomys pattersoni, a 7-foot-tall rodent that lived 8 million years ago.

Kevin Schafer/Corbis

Pattersoni's modern relative, the capybara, with baby. Capybaras reach a little over two feet in height.

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A group of international fossil hunters are reporting a discovery in South America that had them rubbing their eyes in disbelief. As NPR's Christopher Joyce reports, the researchers found a skeleton of a rodent that is bigger than a human. The animal had six-inch long teeth, and weighed nearly one ton.

"It's about 10 times the size of the largest living rodent," says Marcelo Sanchez of the University of Tübingen in Germany.

The giant rodent's closest relatives are the South American capybara and the pacarana, whose Latin name means "terrible mouse."

But not to worry. Phoberomys pattersoni, possibly eight to 10 feet long, lived about 8 million years ago in Northern Venezuela. Like all rodents, it was a gnawing animal. Scary? More like "cuddly."

"You know, if you want a picture of what this animal looked like," says Sanchez, "picture a guinea pig the size of a horse."

The study appears in the current issue of Science magazine.