With regard to the reasons for the extinction of dinosaurs, it is still constantly being studied. For a long time, the most authoritative view is that the extinction of dinosaurs, and 6500 million years ago a large meteorite related. According to the research, when there was a 7-10 km in diameter asteroid crashed into the Earth's surface, causing a big explosion, a large amount of dust thrown, such as the atmosphere, forming clouds of dust cloud, resulting in a temporary cessation of photosynthesis of plants, Therefore, the extinction of the dinosaurs.
Asteroid collision theory, and soon gained the support of many scientists. In 1991, in Mexico's Yucatan peninsula, long period of time found a place in the meteorite impact craters, a fact further confirmed this view. Today, this view seems to have become dogma.
But there are also many people of such an asteroid impact theory of skepticism because the facts are: frogs, crocodiles and many other pairs of temperature-sensitive animals withstood the Cretaceous and survived. This theory can not explain why only the dinosaurs die off. To date, scientists have made assumptions about the causes of extinction of the dinosaurs have been no less than a dozen relatively rich in provocative and dramatic "meteorite collision said," is just one of them only.
Addition to the "meteorite collision that" outside the main points of view on the extinction of the dinosaurs are the following:
First, climate change, said. 6500 million years ago, the Earth's climate suddenly changed, the temperature dropped sharply, resulting in decline in atmospheric oxygen, so that the dinosaurs could not survive. Some people think that dinosaurs were cold-blooded, but with no hair or a warm organ, unable to adapt to the decline in the Earth's temperature, were frozen to death.
2, species struggles. The late dinosaurs, small mammals first appeared, these animals are rodents and carnivores, may dinosaur eggs for food. Because of this lack of natural predators of small animals, more and more and eventually finished the dinosaur eggs.
3, continental drift, said. Geological studies have shown that, in the era of the dinosaurs to survive there is only one continent on Earth, namely, "Pangea." As the earth's crust changes, the continent took place in the Jurassic larger division and drift, culminating in the environment and climate change, dinosaurs be extinct.
Fourth, changes in geomagnetic said. Modern biology has proved that certain biological death and magnetic field. More sensitive to magnetic fields of biological, in the Earth's magnetic field changes, it also could lead to extinction. It seems therefore that the extinction of dinosaurs may be related to changes in the Earth's magnetic field.
5, angiosperms poisoning said. The late dinosaurs on Earth the gradual disappearance of gymnosperm, replaced by a large number of angiosperms, gymnosperms, these plants contain toxins that are not, a huge dinosaur body appetite odd large, a large number of intake of angiosperms led to accumulation of toxins from the body too more than was finally poisoned.
6, acid rain, said. The late Cretaceous period may be too strong under the acid rain, the soil, including trace elements including strontium be dissolved, dinosaurs through drinking water and food intake directly or indirectly, strontium, acute or chronic poisoning, the last batch after batch died.
With regard to the causes of dinosaur extinction hypothesis, far more than the above-mentioned these types. However, these types of the above-mentioned hypothesis, in the scientific community has more supporters. Of course, each of the above is a saying there imperfections. For example, the "Climate Change said," does not clarify the causes of climate change. After inspection, some small dinosaurs Coelurus enough with the early phase of small mammals to compete, so "the struggle of species that" there are loopholes. In modern geology, the term "continental drift theory" itself is still a hypothesis. "Angiosperm poisoning said," and "acid rain, said" The same lack of sufficient evidence. Therefore, the real reason for dinosaur extinction,
Remain to be further explored.