During the Cretaceous period, an asteroid-like substance smashed the crust of Central America, and molten magma spewed out, forming a super volcanic eruption. Volcanic ash and toxic gases cover the sun, plants can't carry out photosynthesis, and the oxygen content in the air is extremely low. To sum up, this is the reason for the extinction of dinosaurs, but the impact is not global and the duration is not that long, so the extinction of dinosaurs is still an unsolved mystery.

People are still studying the reasons for the extinction of dinosaurs. The main points are as follows:

1, climate change theory. 65 million years ago, the earth's climate changed suddenly and the temperature plummeted, which led to the decrease of oxygen content in the atmosphere and dinosaurs could not survive. Some people think that dinosaurs were cold-blooded, without hair and warm organs, unable to adapt to the decline of the earth's temperature, and all of them froze to death.

2. Volcanic eruption theory. Because the volcano erupts, it spews a lot of carbon dioxide, causing the global greenhouse effect and causing food death. Moreover, the volcano spewed fire, resulting in the release of a large amount of salt, the destruction of the ozone layer, harmful ultraviolet radiation on the surface, resulting in extinction.

3. Theory of orogeny. At the end of Cretaceous, the swamp was dried up by orogeny, and many dinosaurs whose home was swamp could no longer survive. Because of the changes in the post-Qi Dynasty, plants also changed, and herbivorous dinosaurs could not adapt to new foods and died out one after another. The herbivorous dinosaurs became extinct, and the carnivorous dinosaurs also lost their dependence. As a result, they also became extinct. This extinction process lasted 65,438+0,000-20 million years. By the end of Cretaceous, it was extinct on the earth.

4. Species Struggle Theory At the end of the dinosaur era, the first batch of small mammals appeared. These animals are rodent carnivores and may feed on dinosaur eggs. Due to the lack of natural enemies, more and more small animals finally ate dinosaur eggs.

5. Ocean ebb theory. According to Barker, when the ocean ebbs and the land borders, creatures contact each other, which leads to the extinction of some species. Kangaroos, for example, can survive in the sea fish mobile phone stations in Europe, but they will become extinct when they meet other animals on the South American continent. In addition to this relationship between eating and being eaten, there are also infectious problems such as diseases and parasites.

6. Theory of species aging. People think that the dinosaur's body was too big because it flourished for hundreds of millions of years. Moreover, bones such as horns are also extremely developed, which causes great inconvenience to life and eventually leads to extinction.