Tyrannosaurus Rex, also known as T. rex, lived in what is now western North America. At the time the T. rex lived, the continent was known as Larimidia. The T. rex lived during the Upper Cretaceous Period, between 85-66 million years ago. The T. rex is thought to be one of the last non-flying dinosaurs to live before the Cretaceous-Paleogene extinction event.


The Tyrannosaurus Rex was one of the largest land predators ever found on earth, reaching a length of nearly 40 feet and a height of 13 feet at the hips. The T. rex could weigh anywhere from four to seven tons. Based on fossils, scientists know that the T. rex had a massive skull and a long, heavy tail to support its mass. The arms, although proportionally very small, were powerful with two clawed digits (like fingers). The hindlegs of this dinosaur were long and powerful. Studies have suggested that the T. rex possessed the most powerful bite of any land animal to have lived on Earth. According to a study by Karl Bates and Peter Falinkgham (2012), the bite of a T. rex was three and a half times more powerful than that of a Great White Shark and 15 times more powerful than the bite of an African Lion. Scientists also believe that the body of the T. rex was partially covered in feathers for at least part of its existence on Earth. Scientists are also not in agreement concerning whether or not the T. rex was cold-blooded (like a typical reptile). There is considerable evidence that the T. rex had some mechanism for maintaining a more constant body temperature.


The massive head of the T. rex supported a jaw that was at least four feet thick and which contained 50-60 teeth, some which could measure up to 9 inches long. Its powerful teeth were used to extract flesh from its prey and to slice it up once in its mouth. A powerful T. rex could eat over 500 pounds of meat and bone in a single bite. Rotting bacteria found to exist between the teeth of the T. rex likely gave it a “septic” bite, causing fatal infections in dinosaurs it wounded but failed to kill. The Tyrannosaurus is thought to have had a very keen sense of smell.


In 1990, fossil hunter Sue Hendrickson found the most complete fossil of a Tyrannosaurus Rex skeleton ever found (85 percent complete). It was eventually sold to the Field Museum of Natural History for $8 million dollars. The museum itself spent over 25,000 man hours removing rock from the bones.