What is a dinosaur?

Páginas: 11 (2554 palabras) Publicado: 26 de junio de 2010
1. Introduction
2. The origin of the dinosaurs
3. The Benefits Of The Upright Position
4. The Empty ecospace

1. Introduction

Dinosaurs are an extinct group of reptiles, known only through fossils. The word dinosaur fossil has a pejorative meaning in common parlance, is called a dinosaur to someone or some organization that continues to live when you are no longer needed, afossil is an old person, dry and boring. So why do so many people find fascinating?
Dinosaurs respond to the child in all of us, expand the imagination and awaken our wonder. How can they be so big? How long do they live? Why extinct? Undoubtedly, only a sad and boring, a real fossil, would not be able to marvel at the thought of a Diplodocus 27 meters long, or a huge Tyrannosaurus, with teethlike knives.

Apparently, the dinosaurs of interest to people of all ages and all nationalities. Every few weeks, appear in the newspapers about the finding of the skeleton of another dinosaur somewhere in the world, or some theory about the behavior of these beings or the reason for their extinction. The dinosaurs have proved a useful means of news on matters relating to the evolution andhistory of life. Just show the word dinosaur in a headline to arouse readers' interest. This occurs in countries where they are often spectacular dinosaur skeletons, such as single state, Canada and the Soviet Union, and in others, like Britain, where they are found from time to time.
Paleontologists, ie, scientists who study fossils of dinosaurs and other animals and plants have become extinct, aremotivated by many of the questions we have mentioned children. The pleasures that causes
multiple study of dinosaurs.

The excitement of finding bones, the thrill of discovery, the painstaking excavation of the remains, their preparation and cleaning in the laboratory, analysis of animal life and the combination of science and art produced in the reconstruction of aspect of the creature. Theseare topics covered in this chapter.
In general it is true that dinosaurs are huge reptiles. The word dinosaur means terrible lizard, and synthesizes the impression that we produce. The largest of them were the giant animals that ever existed on earth. These include the long-necked herbivorous sauropods, including Seismosaurus, reaching the length of five buses parked one behind the other, andthe Ultrasauros, with a height of 15 feet when stretched his head up as giraffes. For their size, these giants vied with larger whales that occupy the oceans today. It is somewhat surprising, because water acts as a support for the large size of the whale, but dinosaurs lacked this support. The largest land animals that we know today, elephants, weigh five tons, a negligible when compared to theestimated weight of Ultrasauros: the equivalent of 22 elephants.
The carnivorous dinosaurs, but did not reach these magnitudes, were also enormous. The Tyrannosaurus measured 15 meters long, 6 feet tall and had very effective teeth for cutting meat, 18 inches long. It was the largest land carnivore of all time.
Nevertheless, not all dinosaurs were monstrous. Many carnivorous hunters were agile,lightweight, no larger than a child of the human species, and fed on lizards and mammals the size of a mouse. Some of the smaller, the saltopus and Compsognathus, measuring 50 to 90 centimeters respectively, and may not have weighed more than three pounds. The Micropachycephalosaurus was the smallest, herbivore, the size of a small rabbit.
In general, the dinosaurs were bigger than mammals. Themean size of dinosaurs taken together would have been somewhat greater than that of humans, while the average for all mammals would be about a tenth. Compensates for the enormous size of the large mammals such as elephants, rhinos and hippos, with the fact that most of them are small shrews, bats, mice and other rodents.
The dinosaurs are a natural group, phylogenetic, with a single common...
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