No other dinosaur has inspired more terror, awe, and imagination than Tyrannosaurus rex. T. rex (as it is popularly called) was the supreme ruler of the prehistoric world and is the best known of all dinosaurs. The name Tyrannosaurus rex means “king of the tyrant lizards.” The name for this dinosaur is well deserved. T. rex proved to be the largest and most ferocious predator ever to walk the Earth. T. rex was just one of the group of dinosaurs called tyrannosaurs. The tyrannosaurs were theropods, which means that they were meat-eating dinosaurs that walked on their two back legs. Where and when Tyrannosaurus rex livedTyrannosaurus rex lived about 80 to 65 million years ago, during the end of the period of the Earth's history known as the Cretaceous. Fossil remains of T. rex have been found in North America, mostly in South Dakota, Montana, and Wyoming in the United States. Fossil remains also have been found in Canada and in Asia. Among the most significant T. rex fossil discoveries ever made was in the Badlands of South Dakota in 1990. There, the largest, most complete, and best-preserved T. rex skeleton was found. It was named Sue in honor of its discoverer. Sue was later put on display at the Field Museum in Chicago, Illinois. Scientists believe that T. rex lived in forests and in forest clearings. Physical featuresT. rex was a massive dinosaur known for its enormous head and tiny front legs. It could reach a length of 42 feet (13 meters) and weighed up to 8 tons. If it stood straight up, T. rex would be more than 21 feet (6.4 meters) tall. The huge head of T. rex could reach 5 feet (1.5 meters) in length, and its skull alone weighed up to 600 pounds (270 kilograms). Its eyes allowed it to see forward as well as to the sides. T. rex had about 60 teeth with saw-like edges that curved inward so nothing could escape from its jaws. The teeth could reach a length of 6 inches (15 centimeters). As they wore out, new teeth replaced them. T. rex had large, muscular back legs, each with three clawed toes. Its front legs were tiny but very strong, and each front foot had two clawed toes. Its stiff tail was held off the ground. BehaviorT. rex preyed on plant-eating horned and duckbilled dinosaurs. T. Rex may have hunted in packs to bring down much larger dinosaurs. It most likely was an ambush predator, lunging out from behind trees in a surprise attack. Scientists estimate that T. Rex could run 20 miles per hour (32 kilometers per hour) for short distances. This speed would have allowed it to chase down and catch its victims after such ambush attacks. Some scientists believe that T. rex may have used its hands to grip struggling prey with its hooklike claws. T. rex also may have been a scavenger, feeding upon dead animals. Scientists believe that T. rex chewed its prey before swallowing, instead of gulping it down in whole chunks. Even by modern standards, T. rex still reigns as the ultimate predator. |