A fully grown Tyrannosaurus was probably the largest land carnivore of all time. It was more than 47 feet long and the skull alone was 4 feet long. The Tyrannosaurus was a biped. (a biped animal is an animal having 2 feet. for example: birds & humans). The Tyrannosaurus walked on powerfully developed hind legs. If it stood upright, the Tyrannosaurus was 20 feet tall but its ordinary pose was stooped forward. The estimated weight of a Tyrannosaurus is almost eight tons. The body is massive and its neck is short and thick. The skull was large in relation to its body. It was armed with pointed teeth up to 6 inches long. The teeth had serrated edges which were effective for cutting and slicing. The Tyrannosaurus' forelimbs were useless except for grabbing things in short range. Its tail served as a counter balance to the body. Musculature was well developed. Especially the muscles for biting and chewing and support and mobility. The Tyrannosaurus was a rare animal. There was perhaps only one Tyrannosaurus every 100 square miles. The Tyrannosaurus did not live in packs probably because if a bunch of Tyrannosaurus lived so close together, they would kill all the other dinosaurs so quickly there would be no food. Some paleontologists have argued about how fast the Tyrannosaurus could run. Some say that the Tyrannosaurus' top speed is up to 70 kilometers per hour though recent studies indicate that a full-grown Tyrannosaurus could run only about half that fast. These studies show that the Tyrannosaurus had a good reason not to run fast. If the Tyrannosaurus ran fast, there was a great chance that the Tyrannosaurus would trip and fall.

The Tyrannosaurus lived in the Cretaceous period. The Cretaceous period was one of the most important geological periods. It lasted for 80 million years beginning 144 million years ago and ending 65 million years ago. The Cretaceous period was the last period in the Mesozoic Era. Since there was no extinction between the Jurrasic period and Cretaceous period, the population of dinosaurs increased. But by the end of the Cretaceous period, all dinosaurs died because of the great extinction occurring around 65 million years ago which then marked the end of the Cretaceous period. The Cretaceous period was warm, mild, and moist. During the Cretaceous period, there were a lot of trees and plants which grew all over the world. Flowering plants had multiplied, big water lilies got even bigger, and poison ivy grew just about everywhere. The warm, mild, and moist weather of the Cretaceous period made things better for the Tyrannosaurus because the Tyrannosaurus because the Tyrannosaurus a cold-blooded dinosaur. It wasn't so cold and it wasn't so hot. If it was too cold, the Tyrannosaurus would freeze and if it was too hot, the Tyrannosaurus could die of heat.

Tyrannosaurus, The new Encyclopedia Britannica, Volume 12, Encyclopedia Britannica, Inc., 1987.

Jeff Hecht, Deborah Byrd ,If Tyrannosaurus Triped* (February 12, 1996), http://www.earthsky.com/1996/es960212.html, February 12, 1996.

Picture from: http://www.slsc.org/develop/docs/mod3/mod3_2/mod3_22/ep2517g.htm.

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