Allosaurus was a fierce dinosaur that roamed the Earth before the similar but more well-known Tyrannosaurus rex appeared. The name Allosaurus means “other lizard.” This dinosaur had bony ridges above each of its eyes. It also had a ridge of bone running down the center of its face between its eyes to the tip of its snout. Allosaurus is a member of the group of dinosaurs known as theropods. The theropods were meat-eating dinosaurs that walked on their two back legs. Where and when Allosaurus livedAllosaurus lived about 163 to 144 million years ago, during the period of the Earth's history known as the Jurassic. Most Allosaurus fossils, or remains, have been found in North America, in Colorado, Utah, New Mexico, Montana, South Dakota, and Wyoming. Remains also have been discovered in Africa and Australia. Allosaurus, like most other dinosaurs, was a land animal. It most likely lived near areas with thick plant life, close to the plant-eating dinosaurs that it preyed upon. Physical featuresAllosaurus was a large dinosaur that stood and walked on its two muscular hind legs. It reached up to 39 feet (12 meters) in length, stood about 15 feet (4.5 meters) tall, and weighed up to 2 tons. The massive head of Allosaurus measured about 3 feet (1 meter) long and was supported by a short, thick neck. Large, open spaces in the skull made its head fairly light. The sharp teeth of Allosaurus were curved and had sawlike edges. They were 2 to 4 inches (5 to 10 centimeters) long. The dinosaur's powerful jaws could open wide to tear off larger chunks of food. Allosaurus had sharp claws on the three toes of each hind foot. It also had long, grasping claws on the three toes of each front foot. These claws grew as long as 6 to 10 inches (15 to 25 centimeters). They helped make the animal's short but strong front legs deadly weapons. The long, heavy tail of Allosaurus may have helped the animal balance itself. BehaviorAllosaurus was a meat-eating dinosaur that preyed on plant-eating dinosaurs. When it hunted alone, Allosaurus would hide among the thick plants then jump out on its prey. It would grab hold with its long front claws and sink its teeth into the neck of its victim. Some scientists believe that Allosaurus also hunted in packs. Together, a pack of Allosaurus could bring down very large dinosaurs, such as Apatosaurus and Diplodocus. It is possible that Allosaurus was also a scavenger, feeding upon carcasses of dead or dying animals. Scientists believe that Allosaurus reproduced by laying eggs. |