A Whole Lotta Rodent!

Scientists have identified the fossilized remains of the world's biggest rodent. How big? About 1,500 pounds, 9 feet long, and more than 4 feet tall—roughly the size of a buffalo. “Imagine a weird guinea pig, but huge, with a long tail for balancing on its hind legs,” was how one scientist described it. Like all rodents, including mice, squirrels, and beavers, it had strong front teeth that never stopped growing but were worn down by its constant gnawing of tough foods, probably sea grasses.

The 90 percent–complete fossil, nicknamed Goya, was found in Urumaco, Venezuela. Although Urumaco is now a desert town, scientists believe that eight million years ago, when Goya lived, a mighty river ran through the area, which was also home to 40-foot crocodiles, 8-foot turtles, and 9-foot, meat-eating flightless birds.

These big, slow animals evolved in South America when the continent was an isolated island. Scientists aren't sure why they all died out but think it may be because three million years ago a land bridge—the Isthmus of Panama—emerged, connecting Central and South America. Animals like Goya would have been too big to hide and too slow to escape new predators that moved in from the north.


The very old remains of a plant or an animal.

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  1. What is Urumaco, Venezuela, like today?
    [anno: Urumaco, Venezuela, is a desert town.]
  2. The environment around Urumaco has changed in the past several million years. Many species of animals lived in Urumaco when Goya did. What has happened to the river? Why might the river have been important? How would this changing environment affect the other animals living when Goya did? Write a few sentences to explain your answer.
    [anno: The changing environment would have affected all the animals. If the river dried up, the other animals, like the crocodiles and turtles, would lose their home. The river probably supported a lot of life in that area. When the river dried up, animals all along the food chain were probably affected.]