A dull, heavy, stiff, awkward... So in the XVIII century described the dinosaurs German scientist Friedrich Theodor Fischer. Since were opened their first remains of dinosaurs used very unimportant reputation: huge creatures, weighing about bend tons, with miniature brain, absolutely not able to adapt to climate change, although inhabited our planet for one hundred forty million years. No wonder they were doomed to destruction in accordance with the laws of its own selection and vanished without a trace.

If everything had been? Paleontologists increasingly reflect on this question. For example, the notorious slowness" of the dinosaurs. English scientist R. Alexander, from Leeds University, measuring fossilized traces left by certain species of dinosaur found that on four legs dinosaurs moved at a speed of four miles an hour and the speed of the dinosaurs, moving only his hind legs, reached thirteen kilometers per hour. And paleontologist Robert Becker from the Baltimore University believes that the speed of movement of some species of dinosaur could reach even fifty miles an hour.

The dynamism of the dinosaurs convinced many paleontologists that these animals, klassifitsirovany since ancient times as reptiles, were warm-blooded...! They did not feel the need to lie in the sun, in order to maintain the desired temperature of the body.

In proof of this hypothesis, scientists at Yale University argue that the ability of the dinosaurs easy to take the vertical position is much characteristic of warm-blooded animals. Another argument is a way of eating. If the dinosaurs were cold-blooded animals with very slow metabolism, the need for food they would be limited. At the same time, the study of fossils of dinosaurs in the canadian province of Alberta has shown that predatory dinosaurs had a very healthy appetite. This, in particular, shows the arrangement of their teeth.

Physiology of dinosaurs also confirms the fact that they were warm-blooded animals. For example, pumping blood to the head of baresave sitting on his neck long, six meters, require the circulatory system, a much more developed in comparison with the cold blooded animals.

The last argument in favor of the hypothesis of teplokrovnosti dinosaur was the study of their bones. On the surface of bones of dinosaurs has many holes, indicating the presence of well-developed circulatory system, while normal bone reptiles completely smooth. In addition, the lower jaw of a dinosaur consists of a single bone, and the lower jaw of reptiles - of several separate bones.

But the biggest mystery remains mysterious disappearance of the dinosaurs at the end of the Cretaceous period. 65 million years ago the Earth was something difficult to explain. In the result of any of Grozny and, apparently, sudden event extinct whole animal world. Forever gone dinosaurs flying lizards. The era of extinction lasted for about 200 years. Sedimentary rocks of the oceanic sediments formed at that time, give us a documentary evidence of the transience of those dramatic events - the whole cemetery of dinosaurs.

Hypotheses explaining the reason of such unusual catastrophe, being piled up one on top of another is sufficiently plausible to the most fantastic. This and the sudden onset of an ice age, and changing of poles of the Earth's magnetic field, and pathological causes - for example, changes in anatomy or physiology of animals.

Climate hypotheses three known. The first assumes that at the end of the Cretaceous period there were significant cooling to low temperatures, are destructive of the dinosaurs due to the lack of insulating cover - fur, feathers, fat, and other "gadgets"than be saved from the cold of modern animals and birds. According to another version, the reason of accident in a sudden change of the oxygen regime in the atmosphere. Extinct giants have consumed a large quantity of atmospheric oxygen, and the sudden decrease of its concentration in the atmosphere has led to the fact that dinosaurs died from suffocation. Third, the "climatic" hypothesis - strengthening of cosmic radiation that caused the death of animals.

Several versions are trying to explain the extinction of the dinosaurs in the result of external biological factors - for example, changing food resources. Violation of the diet of the dinosaurs could be caused by sharp changes of the vegetation cover of the Earth. But the hypothesis of "competition mammals" implies that infest mammals simply ate eggs of dinosaurs, not allowing them to multiply.

Very interesting hypothesis about the death of the dinosaurs the explosion of a supernova. The observation of this phenomenon is relatively rare. A supernova is an explosion of such enormous forces that their luminosity increases in billions of times! Supernova generate strong flow of gamma radiation that would kill organisms. Thus, if 65 million years ago, somewhere in the vicinity of the Solar system was an explosion of a supernova and the atmosphere of the Earth has not coped with their protective functions and missed part of deadly radiation to the earth's surface, from radiation sickness must kill not just the dinosaurs but most of the other inhabitants of the planet.

The group of the American scientists have put forward a hypothesis. In the study of a layer of clay, referring to the period described accident, it was discovered high content of iridium. Iridium on Earth is very small, so any lived in the breed abundantly iridium chronologically comparable with the age of the proceeds of this rare metal from outer space. Asteroids are rich in this chemical element, and therefore it is quite reasonable to assume that the source of iridium in the period catastrophic extinction of the dinosaurs could be an asteroid. Moreover, the meteorites are the fragments of asteroids always contain iridium. Perhaps the asteroid with a diameter of about 10 kilometers crashed into the Ground, and in horrible explosion in the Earth's atmosphere rose thousands of cubic kilometers of the formed dust. This cloud for several years blocked access to the sun, and in the coming universe of darkness on Earth has interrupted the process of photosynthesis. Came global hunger. Nearly all vertebrates massive 20-30 kilograms died of starvation.

But maybe no immediate extinction was not? New evidence that the extinction of many groups of dinosaurs did not happen instantly, and has lasted thousands of years. And it is possible that some groups of dinosaurs disappeared already in the "historical" time in the memory of mankind - remember the notorious dragons. Some dinosaurs could survive to our days... anyway, dinosaurs will present the science is not yet another surprise.