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Cover Story

Cover Story - Spanish Version

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Comprehension Quiz

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That's One Mighty Mouse

Last Wednesday, scientists in South America announced the discovery of the world's biggest rodent. But don't leap onto a chairóthis giant rat lived about 4 million years ago.

Scientists say the rodent was about 15 times heavier than the largest living rodent, the capybara.

The ancient animal's skull was found in 1987, but the fossil sat in a museum in Uruguay for 20 years. "It's a beautiful piece of nature," says Ernesto Blanco, who studied the fossil. "You feel the power of a very big animal behind this."

The creature was named Josephoartigasia monesi, or J. monesi, after Alvaro Mones, an expert on South American rodents.

Next: He's Out of the Running