Uruguay's paleontologist Gustavo Lecuona, left, and Washington Jones stand in a room of fossils stored in Uruguay's Historic Natural Museum in Montevideo, Wednesday, Jan. 16, 2008. Uruguayan scientists say they have uncovered fossil evidence of the biggest species of rodent ever found, one which roamed South America about 4 million years ago. The skull was found nearly two decades ago by fossil collector identified as Sergio Viera, from Argentina, who donated it to the museum.[Agencies]