SCIENCE NEWS
January 16, 2008
A Mighty Mouse
Scientists in South America announce the discovery of the world's biggest rodent
There's a new giant on the block--a giant rat! This week, researchers in South America reported the discovery of the greatest rodent that ever lived. Its skull was found in 1987, and scientists' research on the creature was just published last week. It is believed to have been the size of a bull and weighed as much as car. The beast was named Josephoartigasia monesi (also called J. monesi) after Uruguayan scientist Alvaro Mones, who was an expert in South American rodents. The fossil was found on Kiyu Beach on the coast of Uruguay.
 |  ROYAL SOCIETY/AFP/GETTY IMAGES An artist’s drawing of what the head of Josephoartigasia monesi, the largest rodent ever found, might have looked like. |
Most rodents weigh no more than two pounds. The largest living rodent, the capybara, weighs about 130 pounds, but would be a lightweight compared to J. monesi, whose weight could have ranged from 1,000 to more than 2,000 pounds. The team of scientists estimated the animal's size by measuring its skull and comparing it to other South American rodents.
Before it was identified as a new species, the fossil sat in Uruguay's Natural History Museum for 20 years. It was rediscovered by museum curator Andres Rinderknecht, who with, the help of researcher Ernesto Blanco, examined the specimen and wrote the study about the massive beast. "It's a beautiful piece of nature," says Blanco. "You feel the power of a very big animal behind this." Until now, the largest-known rodent was Phoberomys pattersoni, a 1,500-pound rodent found in Venezuela in 2003.
Researchers say the new rodent species is more closely related to guinea pigs than mice. "These are totally different from the rats and mice that we're accustomed to," said Bruce Patterson of the Field Museum in Chicago. "These were things with trunks on their noses, huge claws on the hands. They look like somebody just made them up."
Ancient HistoryAbout 65 million years ago, South America had a population explosion of different species of rodents, but most died out when changes in the climate destroyed their habitat.
The megarodent lived between two and four million years ago in the rain forests of South America alongside saber-toothed tigers, flesh-eating birds and armadillos. Its 21-inch-long skull sported enormous 4-inch incisors, but scientists say the prehistoric creature had weak jaw muscles, which suggests that it dined on soft vegetation, fruit and marine plants.
Not much is left of the giant rodent, but scientists believe that this discovery will help them find out more about the plants and animals that were in South America during the time this animal was alive.
