How did the dinosaurs become extinct? Did they die from lack of oxygen?

German scientists recently proposed that the extinction of the dinosaurs was caused by severe "space weather" at that time. That is to say, strong particle flows from the universe broke into the earth's atmosphere and caused drastic changes in the earth's climate, resulting in Dinosaurs become extinct.

According to the German "Science Illustrated" magazine, Professor J?rg Farr from the Institute of Astrophysics in Bonn said that the earth was caught in a strong cosmic particle flow "storm" 60 million years ago. "middle. When encountering such a storm, the number of various particles entering the earth's atmosphere at high speed will reach hundreds of times as much as usual, "tearing" the molecules in the atmosphere into condensation nuclei necessary for the formation of rain, eventually causing the clouds in the earth's atmosphere to thicken. , rainfall is frequent and the temperature drops sharply.

Scientists believe that it was the explosion of cosmic particle flows that caused drastic changes in the earth's climate conditions, and that dinosaurs that could not adapt to such climate changes became extinct in a relatively short period of time

During the Mesozoic Era in Earth's history, insects inhabited a wide variety of reptiles—dinosaurs. Hundreds of dinosaur fossils have been discovered in the world. Such a huge animal group that dominated the earth for 160 million years suddenly perished at the end of the Cretaceous period. A puzzling chapter in the history of biology was written.

So far, various explanations for the reasons for the extinction of dinosaurs cannot be justified. In recent years, the hypothesis of an asteroid impact on the Earth put forward by American physicist Louis Alvarez has attracted much attention from all parties. When he was studying the upper layer of the Cretaceous strata in Gubbio, Italy, he found that the content of the trace element iridium suddenly increased by more than 30 to 160 times compared with strata from other periods. Later, people sampled and tested from many locations around the world and found the same In conclusion, the abnormal increase in the total amount of iridium in the formations at the end of the Cretaceous is indeed universal. So Alvarez believed that an asteroid with a diameter of about 10 kilometers hit the earth at the end of the Cretaceous period, producing dust that obscured the sky and the sun. It caused huge changes in the surface climate environment and led to the demise of the dinosaurs. However, there are many doubts about using asteroid impacts to explain the increase in iridium content in rock formations and the extinction of the dinosaurs.

1． Asteroids are generally made of silicon and iron elements. Even if such a huge asteroid falls on the surface of the earth, it will not be completely missing even after a long time. However, such a large meteorite has never been found on the earth;

2． Most of the rock formations at the end of the Cretaceous were igneous rocks formed by the cooling of lava, and sedimentary rocks formed by dust accumulation accounted for only a small part of the surface. Could the dust raised by just one asteroid impact bury most of the animals and plants on Earth at that time into rock formations thousands of meters deep?

3． Can the iridium element contained in an asteroid be evenly distributed and cover the entire earth's surface? Iridium element also exists deep in the earth. Why is it only speculated that iridium element comes from outside the earth instead of from inside the earth?

We know that the thermonuclear reactions inside the earth will continuously accumulate huge energy. Once the earth's crust cannot bear it, the internal pressure will break through the earth's crust and suddenly release to form a large explosion. Iridium, an element mainly found in the core of the earth, was brought to the surface of the crust from the depths of the earth through lava eruptions during large explosions. The clay layer recognized as marking the end of the Cretaceous period was formed by the accumulation of large amounts of volcanic ash. Therefore, the general increase in iridium content in the formations at the end of the Cretaceous proves that there was a widespread violent eruption of the earth's crust at that time.

Fossil archives tell us that the death time of most dinosaurs and the production of most dinosaur egg fossils was at the end of the Cretaceous. All dinosaurs and dinosaur egg fossils that have been discovered are preserved in iridium-rich in the strata under the thin clay layer, which coincides with the time recognized by the geological community as a series of dramatic changes in global crustal structures such as the large-scale orogeny at the end of the Cretaceous.

Among the hundreds of Protoceratops and Ankylosaurus fossils unearthed in the late Cretaceous strata of Bayinmanduhu, Inner Mongolia in recent years, a large number of complete dinosaur skeletons were piled together in groups. Judging from the burial posture, they died in extreme pain, and there were also skeletons of a whole group of dinosaur cubs. This scene shows that they died in a catastrophic mass death, and the bodies were quickly buried in the same place after death (in other parts of the world, the bodies are also buried in the same place). And the swelling┖焐?Mu's success is also contradictory?Anzhongsha瀹瀇瀇倰怅?art?cutweftthatch?Nao糴crowfatyard? The roaring locusts slowly throw themselves into the nets, and the leech is thrown into the net. The emperor rushes to make an appointment. The machine eyes reach the ang? The camel? Howl and stand ┯ Mane Xie? G? A large number of animal and plant species that reflect the characteristics of the earth's environment at that time show that before the end of the Cretaceous, the density and thickness of the earth's atmosphere were far greater than they are now. , the earth's surface was relatively flat, and the global climate was very warm and humid. At that time, the temperature difference between the poles and the equator was very small. In the 1980s, Canadian geologists discovered a patch of water on Ellesmere Island in the Arctic Circle. The forest is dominated by fossil forests, and there are also crocodile and other animal fossils in the forest, indicating that the polar regions once had a tropical climate environment.

The natural environment is the main factor that determines the existence of life. After the earth exploded, when the hot and humid environment that those huge dinosaurs relied on for survival no longer existed, even if some survived, they could not adapt to the relatively cold and dry climate and the distinction between warm and cold seasons. and continue to live in the climatic environment. Therefore, it is natural for most dinosaurs to become extinct.

There are also some dinosaurs that survived (mostly smaller in size) and some that have evolved into primitive birds and mammals as early as the Pauline Period, following natural selection and survival of the fittest in nature. According to the law, in a relatively harsh environment, after 70 million years of continuous evolution, most species have changed their original forms, evolving from cold-blooded animals into cold-resistant warm-blooded animals (birds, mammals and humans) that can regulate body temperature. Of course, after every large-scale species evolution, there will always be some species that remain unchanged. For example, after fish evolved into amphibians, fish continued to survive. There are also a very few reptiles (crocodiles, lizards, scorpions, etc.) that still maintain their original state. The original form of dinosaurs 70 million years ago.

Biological remains in the earth's rock formations reveal that in the history of biological evolution, mass extinctions of species occurred at regular intervals. The extinction of the dinosaurs at the end of the Cretaceous was not the only disaster in the history of biological evolution. In the 1980s, the "Cambrian Explosion of Life" occurred when most invertebrates suddenly appeared in a very short period of time. Just like the evolution of organisms from single cells to multi-cells and the evolution of reptiles to mammals, they require an evolutionary process (as evidenced by the fossil group in Chengjiang, Yunnan, my country discovered in 1984).

So far there is no obvious evidence to prove that the mass extinction of dinosaurs was caused by an asteroid impact. However, the fact that the geological structure of the earth's interior continues to change frequently today shows that environmental "catastrophes" caused by periodic crustal tectonic changes have always played a leading role in the process of biological evolution. Of course, the gradual evolution of small-scale species also occurs throughout the entire process. The evolution of life. Periodic celestial explosions (such as nova explosions) are an indispensable and important link in the evolution of all planets, including the Earth. The marine fossils and seafloor mineral deposits in those mountains are the best explanation for the end of the age of dinosaurs due to drastic changes in the earth's crust

In the Mesozoic Era more than 200 million years ago, a large number of reptiles lived on land, so The Mesozoic Era is also known as the "Age of Reptiles", the first time the earth was widely occupied by vertebrates. At that time, the earth's climate was warm and there were dense forests everywhere. Reptiles had enough food and gradually flourished with more and more species. They continued to differentiate into various types of reptiles. Some have become today's turtles, some have become today's crocodiles, and some have become today's snakes and lizards. evolved into the mammals that exist throughout the world today.

Dinosaurs are the largest of all reptiles and are well suited to living in swamps and shallow lakes, where the air is warm and humid and food is easy to find. So dinosaurs ruled the earth for tens of millions of years, but for unknown reasons, they suddenly became extinct in a short period of time 65 million years ago. What people see today are only the large number of dinosaur fossils left from that time.

The reasons for the extinction of dinosaurs are still being studied. For a long time, the most authoritative view has been that the extinction of the dinosaurs was related to a large meteorite 65 million years ago. According to research, an asteroid with a diameter of 7-10 kilometers fell on the surface of the earth at that time, causing a big explosion and throwing a large amount of dust into the atmosphere, forming a dust fog that blocked the sky and the sun, causing the photosynthesis of plants to temporarily stop. The dinosaurs became extinct as a result.

The asteroid impact theory quickly gained support from many scientists. In 1991, the discovery of an ancient meteorite impact crater in Mexico's Yucatan Peninsula further confirmed this view. Today, this view seems to be a foregone conclusion.

But there are also many people who are skeptical of this asteroid impact theory, because the fact is: frogs, crocodiles and many other animals that are very sensitive to temperature have withstood the Cretaceous and survived. This theory cannot explain why only the dinosaurs died. So far, scientists have put forward no less than a dozen hypotheses about the cause of the extinction of the dinosaurs, and the more exciting and dramatic "meteor collision theory" is just one of them.

In addition to the "meteor collision theory", there are the following main views on the extinction of dinosaurs:

1. The theory of climate change. 65 million years ago, the earth's climate changed suddenly and the temperature dropped significantly, causing the oxygen content of the atmosphere to drop, making it impossible for dinosaurs to survive. Some people also believe that dinosaurs were cold-blooded animals. They had no hair or warmth-keeping organs on their bodies and could not adapt to the drop in earth temperature, so they all froze to death.

2. The theory of species struggle. At the end of the dinosaur era, the first small mammals appeared. These animals were rodent carnivores and may have fed on dinosaur eggs. Due to the lack of natural predators, the small animals grew in numbers and eventually ate up all the dinosaur eggs.

3. The theory of continental drift. Geological research has proven that in the era when dinosaurs existed, there was only one continent on the earth, namely "Pangaea". Due to changes in the earth's crust, this continent experienced major divisions and drifts during the Jurassic Period, which eventually led to changes in the environment and climate, and the dinosaurs became extinct as a result.

4. Theory of geomagnetic changes.

Modern biology has proven that the death of some organisms is related to magnetic fields. Creatures that are sensitive to magnetic fields may become extinct when the Earth's magnetic field changes. It can be inferred that the extinction of dinosaurs may be related to changes in the earth's magnetic field.

5. The theory of angiosperm poisoning. At the end of the Age of Dinosaurs, gymnosperms on the earth gradually disappeared and were replaced by a large number of angiosperms. These plants contained toxins that were not found in gymnosperms. The huge dinosaurs ate a lot. Ingesting a large amount of angiosperms led to the accumulation of toxins in the body. Duo was finally poisoned to death.

6. Acid rain theory. There may have been strong acid rain at the end of the Cretaceous, which dissolved trace elements including strontium in the soil. The dinosaurs directly or indirectly ingested strontium through drinking water and food, and suffered acute or chronic poisoning. The last batch of them died.

There are far more hypotheses about the reasons for the extinction of dinosaurs than the above. However, the above-mentioned hypotheses have many supporters in the scientific community. Of course, each of the above statements has imperfections. For example, the "climate change theory" does not clarify the causes of climate change. After investigation, some small coelurosaurs among dinosaurs were enough to compete with early small mammals, so there are loopholes in the "struggle of species theory". In modern geology, the "continental drift theory" itself is still a hypothesis. "Angiosperm poisoning theory" and "acid rain theory" also lack sufficient evidence. Therefore, the real reason for the extinction of dinosaurs still needs to be further explored.