Eoraptor << `ee` oh RAP tuhr >> was one of the earliest dinosaurs. This small creature lived about 230 million years ago in what is now northwestern Argentina. Scientists believe Eoraptor is one of the most primitive theropods, a group that includes Tyrannosaurus rex and other meat-eating dinosaurs.
Eoraptor had a slender body that grew about 3 feet (90 centimeters) long. Like many early dinosaurs, it ran upright on its hind legs, which were more than twice as long as its arms. Eoraptor’s hands had five fingers, unlike the three-fingered hands of most other theropods. But it used only the three longest fingers on each hand to handle prey. These three fingers ended in large claws. The fourth and fifth fingers were probably too small to be of use.
The only known skeleton of Eoraptor was discovered in 1991. The animal lacked most of the specialized features found in later meat-eating dinosaurs. For example, it did not have a joint within its lower jaw that may have helped later meat-eaters to hold struggling prey. In addition, not all of its teeth were curved and serrated (saw-edged) like those of meat eaters. Eoraptor only had such teeth in the back of its jaw. At the front of the jaw, its teeth were leaf-shaped like those of some plant-eating dinosaurs. Eoraptor probably ate small animals, but it also may have eaten plants.
