Dinosaurs... are reptiles that appeared 245 million years ago and flourished at the end of the Mesozoic Era 65 million years ago. Dinosaurs suddenly disappeared at a certain period and became a mystery in the history of biological evolution on earth. This mystery is still unsolved by no one. The earth's past creatures are all recorded in fossils. Many dinosaur fossils have been found in the strata of the Mesozoic Era. A large number of bones or bones of various shapes can be seen among them. However, in the subsequent Cenozoic strata, no dinosaur fossils can be seen at all. It is inferred that the dinosaurs became extinct together during the Mesozoic Era.
There have been many opinions on the real reason for the extinction of dinosaurs since ancient times, but there is no definite argument. Therefore, it is still an unsolved mystery so far. Here are only some of the more popular ones. The known theories are summarized as follows:
1. Meteorite collision theory:
Sixty-five million years ago, a huge meteorite hit the earth and made it dominate the earth. Dinosaurs became extinct for hundreds of millions of years. This theory was developed by Louis B. of the University of California, Berkeley. Proposed by four scientists including Dr. Albarez.
This huge meteorite is about ten kilometers in diameter. The crater terrain created by the impact has a diameter of 200 kilometers. The energy generated by the impact, if converted into yellow gunpowder, is equivalent to one million billion tons (megaton). Dust diffuses through the atmosphere into the stratosphere. This caused the Earth to remain in darkness for several months. During this period, many creatures, including dinosaurs, became extinct.
2. Comet collision theory:
The "comet collision theory" is based on the paleontologist——David. Raup and John. It started with Sepkoski's thesis that "the extinction of ancient organisms occurs every 26 million years." Louis. Albarez sent this argument and his theory to astrophysicist Charles. Later, Mullah believed that it was due to the gravity of Nemesis, the half-star of the sun, which periodically pushed comets towards the earth.
3. Orogeny theory:
The orogeny that occurred at the end of the Cretaceous caused the swamps to dry up, and many dinosaurs that made the swamps their home could no longer live. Because of the changes in the atmosphere, the plants also changed. Herbivorous dinosaurs could not adapt to the new food and became extinct one after another. The herbivorous dinosaurs became extinct, and the carnivorous dinosaurs also lost their support and became extinct as a result. This extinction process lasted for 10 to 20 million years. By the end of the Cretaceous period, they were finally extinct on the earth.
4. The theory of climate change:
Due to the movement of tectonic plates, ocean currents change, causing huge changes in climate. The severe cold climate caused plants to die, and the dinosaurs lacked food and led to their demise.
5. Volcano eruption theory:
Due to the eruption of volcanoes, carbon dioxide is ejected in large quantities, causing a rapid greenhouse effect on the earth and killing food. Moreover, volcanic eruptions release a large amount of salt, the ozone layer breaks, and harmful ultraviolet rays irradiate the earth's surface, causing the death of living things.
6. The theory of ocean ebbing:
According to Buck, when the ocean ebbs and land borders, organisms come into contact with each other, thus causing the extinction of certain types of organisms. For example, kangaroos can survive on island continents like Europe, but they are extinct when they encounter other animals on the South American continent.
In addition to the relationship between eating and being eaten, there is also the problem of the transmission of diseases and parasites.
7. Warm-blooded animals say:
Some people think that dinosaurs are warm-blooded animals, so they may not be able to withstand the cold weather of the late Cretaceous and may not survive. Because even if dinosaurs were warm-blooded, their body temperature was still not high, probably similar to that of living sloths. To maintain such a body temperature, they could only survive in tropical climate zones. At the same time, dinosaurs' respiratory organs were not perfect and could not fully supply oxygen, and they did not have thick hair to prevent loss of body temperature, but they easily lost a lot of heat from their long tails and legs. The difference between warm-blooded animals and cold-blooded animals is that if the body temperature drops below a certain range, physical energy must be consumed to raise the body temperature, and the body will quickly become weak. Their bodies are too large to enter caves to avoid the cold, so if the cold days last for a few days, they may freeze to death due to exhaustion of energy.
8. Cannibalism theory:
Some people believe that the real cause of the extinction of dinosaurs is that they cannibalize each other - carnivorous dinosaurs feed on herbivorous dinosaurs, and carnivorous dinosaurs feed on each other. As the number of animals increased, herbivorous dinosaurs naturally became fewer and fewer, and finally disappeared. Carnivorous dinosaurs killed each other because they had no meat to eat, and finally died together.
9. Oppression theory:
The rapid increase in the number of dinosaurs caused the extinction of herbivorous dinosaurs when plants were limited, and then they relied on the meat of herbivorous dinosaurs to survive Sexual dinosaurs also died due to lack of food. (Doubt: Why did the number of dinosaurs suddenly increase after about 200 million years of ecological balance? This is an important key to the establishment of the theory, and it also directly caused many scholars to examine the reasons for the abnormal increase in dinosaur production.)
10. Mammal prisoners said:
In the second half of the Mesozoic Era, the ancestors of mammals already existed.
According to fossil records, mammals at that time were very small and their numbers were very limited. It was not until the late Cretaceous that their numbers began to increase rapidly. It is speculated that they are omnivorous and eat insects as their main food. After these small mammals discovered dinosaur eggs, they continued to eat them.
(My opinion: Is this really the case? If mammals defeated the dinosaurs, then as the number of mammalian fossils increased, the number of dinosaur fossils should gradually decrease, but in fact this did not happen The phenomenon of fossil replacement. According to records in other books, the real increase in mammalian fossils occurred after the end of the dinosaur era. Moreover, the dinosaur fossils disappeared suddenly. Therefore, the theory that dinosaurs were wiped out by mammals cannot be established. )
Eleven species of aging theory:
It is believed that the dinosaurs' bodies became too large due to their prosperity for hundreds of millions of years. Moreover, the horns and other bones were also abnormally developed, which caused great inconvenience in life and eventually led to extinction.
The Brontosaurus, the most representative dinosaur, is 25 meters long and weighs 30 tons. Due to its large size, its movements are slow and it has lost its ability to live. In addition, Triceratops and other species went on the road to self-destruction due to the abnormal development of their three horns that continued to grow in size and the bones that protected their heads.
(My opinion: Not all dinosaurs are so huge. There are also small dinosaurs with a body length of only about one meter. In addition, there are also dinosaurs with deer-like bones that can run briskly. But why is this Did the dinosaurs become extinct at the same time? Moreover, the extremely developed bones and other parts of the body of cold-blooded animals are speculated to be able to absorb the outside temperature and release the heat in the body to regulate the body's temperature, which has a very beneficial function. I am skeptical about the idea that dinosaurs became extinct due to the aging of the species)
12. Alkaloid theory:
This theory believes that the last period of dinosaur survival was the chalk. During the 19th century, flowering plants began to appear, some of which contained toxic alkaloids. Dinosaurs died of poisoning due to large amounts of food. Because mammals can use their sense of taste and smell to distinguish poisonous plants, but dinosaurs do not have this ability.
However, plants containing alkaloids did not suddenly appear in the late Cretaceous period. They could already be seen five million years before the dinosaurs became extinct. This theory does not explain why dinosaurs could still survive during this period.
In addition to the twelve above-mentioned theories, there are also "infectious diseases", "radiation from the universe or supernova explosions", "not riding on Noah's Ark", "solar system shock theory" and other relatively new theories. It’s a little-known statement. As for which one is the best, it all depends on everyone’s ideas. There is no certain right or wrong. After all, the mystery of the demise of the dinosaurs has not been truly solved yet!
The oldest reptile fossils can be traced back to the "Pennsylvanian Period" of the Paleozoic Era (310 million years ago - 275 million years ago). Tracing back to its origin, it must have evolved from amphibians. Amphibian eggs need to be in water to develop. Reptiles evolved egg shells that prevent moisture from escaping. This major reform allowed reptiles to live without water.
By the Mesozoic Era, which lasted from 225 million years ago to 65 million years ago, reptiles became the rulers of the earth, so the Mesozoic Era is also called the Age of Reptiles. Large reptilian dinosaurs appeared in the early Mesozoic Era. The herbivorous Diplodocus and Brontosaurus are the largest land animals. Tyrannosaurus rex is a carnivorous dinosaur. There are also ichthyosaurs living in the sea and pterosaurs living in the air.
Reptiles have flourished on the earth for about 150 million years. Among the animals of this era, the most well-known ones are dinosaurs. When people mention dinosaurs, a huge and ferocious animal will appear in front of their eyes. In fact, there are also small and docile dinosaurs among dinosaurs.
Dinosaurs are vertebrate reptiles that were born in land swamps in the Mesozoic Era. They have long necks and tails. The hind limbs are longer than the forelimbs and have a tail. Among them, there are several species that are good at eating meat and several species that are good at eating herbivores. They are huge in size and can be considered the largest among terrestrial animals. In the lower species, their physiques are similar to those of the most ancient crocodiles and rhinoceles, while in the higher species they are slightly similar to birds.
Studying dinosaurs depends entirely on fossils. Paleontologists use fossils to deduce their morphology and habits. According to research by paleontologists, dinosaurs are just like living animals: some are big and some are small; some walk on two legs; some walk on four legs; some eat plants, some eat animals; Some have smooth skin, and some have scales or bony plates on their skin. The only similarities are: all dinosaurs have small brains and lay their eggs on land (this is true for all reptiles).
(1) Brontosaurus:
Some dinosaurs have very large bodies, such as Brontosaurus. During the Jurassic, the climate on Earth was warm and humid, and there were lush forests everywhere. Because of these abundant plant foods, herbivorous dinosaurs flourished. Brontosaurus was also active on the plains of what is now North America at this time. superior.
The weight of Brontosaurus is about thirty-five to fifty tons. Its thick legs are like tree trunks; its long neck is as tall as a seven-story building when it stands upright. It can be said that it is The largest animal on earth.
Although the body of the Brontosaurus is astonishingly large, its temperament is very gentle. It usually feeds on plants in temperate forests, and sometimes walks into swamps. Because the water has buoyancy, it can reduce the heavy burden on its body and at the same time avoid strange creatures. Attack by a ferocious carnivorous dinosaur like a dragon.
(2) Three Chisaurus:
The bone plates and bone fragments on Stegosaurus and Ceratopsaurus can only be used for passive defense, and there is no way to fight back. The situation gradually changed when the dragon appeared. The three-faced dragon is the largest among the dragons. It has two spear-like horns on its head, and the other horn protrudes between the eyes and nostrils. Such a sharp weapon would defeat even the most terrifying carnivorous dinosaurs.
(3) Stegosaurus:
Stegosaurus appeared 150 million years ago. Its biggest feature is the two rows of bone plates rising up on its back and the growth of its tail. With sharp spines. Stegosaurus is a herbivorous dinosaur that moves slowly. The bone plates on its body and the spikes on its tail have become the best defense against carnivorous dinosaurs.
(4) Ankylosaurus:
Stegosaurus is protected by bone plates, but areas that are not covered by the bone plates are still vulnerable to attack. When the stegosaurus gradually became extinct, the ankylosaurus (armadillo dragon) covered with bone plates took its place. Ankylosaurus is like an invulnerable tank, even Tyrannosaurus rex is helpless against it.
(5) Tyrannosaurus rex:
Tyranosaurus rex (Tyrannosaurus rex) is the largest and most brutal carnivorous dinosaur. The time when Tyrannosaurus rex appeared was already at the end of the dinosaur age. About 80 million years ago. Tyrannosaurus rex's body was fourteen meters high and weighed about ten tons. Its hind legs were so thick and strong that they could even support a rhino each.
From the fossils of Tyrannosaurus rex, each of its teeth is as big as an adult's hand, and even its eyes are larger than a human head. Although most of its body is astonishingly large, the pair of forelimbs of Tyrannosaurus rex are small and short, so short that it cannot even put food into its mouth. Murderosaurus also has the same habits as Tyrannosaurus rex and is very ferocious. animals.
[6] Anatosaurus:
Anatosaurus, like Tyrannosaurus rex, appeared at the end of the dinosaur age. The most special thing about Anatosaurus is its head. Its flat and long jawbone resembles a duck's mouth, hence the name Anatosaurus. In the past, people thought that Anadonosaurus lived a life similar to that of a duck, swimming in the water and living on water plants. Later, when scientists studied the fossils of Anatosaurus, they discovered that they did not live on aquatic plants, but on trees on the shore. Aegosaurus also had the same habit.
Who first discovered dinosaurs
The Mantels
There is a small place called Lewis in Sussex, southern England. 180 years ago, a country doctor named Mantel once lived here. Mr. Mantel was full of curiosity about nature and especially loved collecting and studying fossils. When he was not practicing medicine, he often took his wife to climb mountains and wade in rivers to search for and collect fossils. His footprints traveled all over the ditches and ridges with exposed rock formations around him. Over time, Mrs. Mantel also became a "friend of nature" and an expert in fossil collecting.
Iguanodon
One day in March 1822, the weather was very cold, but Mr. Mantel still went out to see patients as usual. The wife was waiting for her husband to come back at home, always worrying whether he would catch a cold. Later, Mrs. Mantel couldn't sit still anymore, so she took a piece of her husband's clothes and went out to meet him in the direction of his visit. She was walking on a road that was being built. The newly dug steep walls on both sides of the road exposed layers of rocks. She habitually observed the newly exposed rock formations on both sides while walking. Suddenly, something shiny caught her attention. "What is this?" she said to herself, and stepped forward to take a closer look. Wow! It turned out to be some strange-looking animal tooth fossils. The fossil teeth were so big that Mrs. Mantel had never seen such large teeth. The excitement of the discovery made Mrs. Mantel forget to give her husband clothes. She carefully removed the fossils from the rock formations and brought them home.
Later, Mr. Mantel returned home. When the lady presented the newly collected fossils to him, he was stunned. He had seen many fossil teeth of ancient animals, but none of them were similar to such a large and strange tooth.
Soon afterwards, Mr. Mantel found many such tooth fossils and related bone fossils near the location where the fossils were found. In order to find out what animals these fossils belonged to, Mr. Mantel brought these fossils to the French naturalist Cuvier and asked the most famous scholar in the world at that time to identify them.
To be honest, Cuvier had never seen such fossils, and all the books and papers he had read written by senior scientists had never mentioned such fossils. However, Cuvier still made a judgment based on his considerable zoological knowledge. He believed that the teeth were from rhinoceros and the bones were from hippopotamus, and they were not too old.
Mr. Mantel was very skeptical of Cuvier's identification. He thought Cuvier's conclusion was too hasty. He decided to continue his research. From then on, whenever he had the chance, he would go to museums around the world to compare specimens and review data.
One day two years later, he accidentally met a naturalist working at the Royal Academy Museum in London. The man was studying a modern lizard living in Central America - the iguana. So Mr. Mantel took those fossils to the Royal Academy Museum in London and compared them with the iguana teeth collected by naturalists, and found that the two were very similar. The overjoyed Mr. Mantel concluded that these fossils belonged to an extinct ancient reptile similar to iguanas, and named them "iguana teeth."
Later, with the discovery of more and more fossil materials, humans have a deeper and deeper understanding of these ancient animals. We know that the so-called "iguana teeth" are actually species A member of a large family of dinosaurs; it is indeed a reptile like the iguana, but it is more distantly related to the real iguana than to other species of dinosaurs! However, according to the rules of biological nomenclature, the Latin text of the species name of this earliest scientifically recorded dinosaur has not changed, and it still means "iguana's tooth". However, its Chinese name is translated as Iguanodon.
So remember: Iguanodon is the earliest dinosaur recorded in the history of science. At the same time, don’t forget the name Mantel and his nature-loving wife.
Who discovered the dinosaurs first
The story of Plot-Garonne-Garonne
The story of Mrs. Mantel’s discovery of dinosaurs is indeed very interesting. Romantic, Mr. Mantel can explore the issue of dinosaur ownership with a rigorous and realistic attitude, which is indeed the first step for mankind to scientifically study and understand dinosaurs.
But in history, humans have discovered dinosaur fossils long ago, but due to limited knowledge at that time, they were not able to correctly interpret these fossils.
As early as my country’s Jin Dynasty more than 1,000 years ago, dinosaur fossils were discovered in Wucheng County, Sichuan Province. However, people at the time did not know that they were the remains of dinosaurs, but regarded them as the bones left by the legendary dragon.
A researcher named Haselted from the University of Reading in the UK based on the clues found in a historical novel "Mr. Milgan's Wife" and after a long period of research, he reviewed With a wealth of information, he recently announced that he had finally discovered the following fact: In 1677, an Englishman named Plot-Garonne wrote a natural history book about Oxfordshire. In this book, Plot-Garonne-Garonne describes a large fossilized leg bone found in a quarry in the parish of Carlovella. Plot-Garonne-Garonne gave a good illustration of this fossil and pointed out that the thigh bone was not that of a cow, a horse or an elephant, but belonged to a species larger than either of them. Big giant.
Although Plot-Garonne-Garonne did not recognize the fossil as being that of a dinosaur or even link it to a reptile, he documented and illustrated it This specimen has been identified by later paleontologists as the thigh bone of a dinosaur called Megalodon, and this fossil was discovered 145 years before the Mantells discovered Iguanodon. Therefore, Haselted believed that Plot-Garonne-Garonne should be the first discoverer and recorder of dinosaur fossils.
The origin of the name "dinosaur"
In fact, humans have discovered dinosaur fossils for a long time. Long before the Mantels discovered the Iguanodon, Europeans had long known that there were many bizarre and huge skeleton fossils buried underground. However, at that time, people did not know their exact ownership, so they were always mistakenly regarded as "the remains of giants". As for us Chinese, we began to collect large ancient animal fossils unearthed from the ground for medicine more than 2,000 years ago, and called these fossils "dragon bones." Who can be sure that the name "dragon bone" has no connection with the discovery of dinosaur fossils?
Psittacosaurus
However, it was not until the Mantells discovered Iguanodon and compared it with an iguana that the scientific community initially determined that it was a lizard-like creature. , long extinct reptiles. Therefore, the names of new types of dinosaurs and other ancient reptiles discovered subsequently were all related to lizards, such as "whale-like lizards", "forest lizards" and so on. At the same time, because these ancient animal fossils that first attracted people's attention are often huge and grotesque, they are really scary.
As the fossils of these terrifying and lizard-like ancient animals continue to be discovered and excavated, more and more types of them have accumulated, and many naturalists have begun to realize that they play an important role in animal classification. Learning should be self-contained. In 1842, the British paleontologist Sir Owen created a name for them in Latin. This Latin word consists of two roots. The former root means "terrible" and the latter root means "lizard". Since then, "terrible lizards" have become a collective name for this large group of reptiles that are related to each other, but behave in a variety of ways. We Chinese have both imagination and generalization ability, so we translated this Latin name into "dinosaur".
Mamenchisaurus
Now we know that there are indeed many terrifying giants in the dinosaur family, but there are also some small and cute "little things".
If you go to the Chinese Palaeozoology Hall not far to the west of the Beijing Zoo, you will see a variety of dinosaurs of different sizes and shapes, from Psittacosaurus, which is less than 1 meter long, to Mamenchisaurus, which is 22 meters long. It will give you a more comprehensive understanding of the dinosaur world.
Now we also know that dinosaurs were not lizards at all. Although they are all reptiles, in the large and complex reptile family, the genetic relationship between dinosaurs and lizards is quite far apart!
From the dexterous Eoraptor to the ferocious Tyrannosaurus rex
—Carnivorous theropod dinosaurs
The overlord of the early Jurassic period—Disosaurus< /p>
In 1942, a larger theropod dinosaur was discovered in the early Jurassic strata of Arizona, USA. Because it had a pair of thin V-shaped bones on its head, scientists named it Named Double Dragon.
Ssangyong
Ssangyong has a stout body, a tall skull, well-developed jaws, a large mouth, and a mouth full of teeth like sharp knives. There are also holes on the front and back edges of the teeth. Small serrated teeth, these features indicate that it can tear up any prey it captures and then swallow the large pieces of meat into its belly. In addition, there are holes in the skull of Ssangyosaurus behind the eyes. These holes are used to better attach the muscles that affect the jaw bones, so the bite of Ssangyosaurus must be very powerful. Scientists speculate that Disaurus may have been the most brutal and ferocious predator in the early Jurassic ecosystem.
Double Dragon and Paleopod Dinosaurs
Buried together
Double Dragon’s hind limbs are thick and powerful, and the feet have sharp claws that can be used to capture and tear prey. . During that period of time about 200 million years ago, Ssangyosaurus often appeared in the highlands between rivers and lakes or in the jungle, chasing various vegetarian animals. They may also like to live alone, and sometimes they may hide in places where they are not easily discovered, waiting for opportunities to sneak up on prey. They may even feed on the carcasses and carrion of animals that died for various reasons like modern hyenas.
my country has also discovered Ssangyosaurus fossils in Jinning County, Yunnan Province.
In August 1987, the dinosaur excavation team of the Kunming Municipal Museum of Yunnan Province unearthed a Yunnanosaurus fossil belonging to the paleopod in Xiyang Township, Jinning County. The unexpected news attracted people from all over to watch. The people here are all Yi compatriots, and they have never heard of dinosaurs. But when they looked at the fossils, some thought the bone-shaped stones looked familiar. Some people told the excavation team that they had seen such stones on the hillside of Muganlang Village in Xiyang Township.
The excavation team followed the messenger to Muganglang Village, where there was indeed a string of dinosaur vertebrae exposed in a small gully. They decided to excavate here. A few days later, a shocking scene occurred. It turns out there are two dinosaurs here! Moreover, there are two complete dinosaur skeletons twisted together, one of which is a paleopod dinosaur, and the other is a carnivorous Disaurus, and the latter's big mouth just bites on the tail vertebrae of the former. Based on the burial conditions of the fossils, scientists speculate that there may be two causes of death for these two dinosaurs: one is that they were both injured in a life-and-death struggle and both died; another possibility is that the paleopod dinosaurs have been dead for many days. The meat on the corpse had rotten and spoiled, and the hungry theropods just tried to fill their stomachs, but unexpectedly they died of poisoning from eating the spoiled paleopod dinosaur meat. Judging from the calm postures of the two, the latter possibility is even greater.
Sinosaurus was the largest carnivorous dinosaur in the early Jurassic, with a length of nearly 4 meters and a long and pointed mouth. There is a cleft in the front of its upper jaw that allows the premaxilla to move. Scientists speculate that its favorite food is probably the internal organs of other animals, because its sharp beak can be inserted into the abdominal cavity of animal corpses, and the two thin plate-like crowns on the top of its head can play a role when its head is inserted into the abdominal cavity of the corpse. The role of supporting the cavity wall.
Disaurus is also a member of the Tethys Sea fauna, so the species found around the world are similar. Their fossils have also been found in modern Antarctica, which shows that the current ice-covered Antarctica was a warm dinosaur world at that time
Great Extinction
Dinosaur fossils have been discovered in recent years, one after another. Types of animals are constantly being discovered, and groups of scientists are eager to study them. Generations of children and their parents have a strong interest in these mysterious ancient creatures. Why is this?
The mass extinction at the end of the Mesozoic Era
This is because many dinosaurs are too big compared to us humans, which makes each of us have to think about why they How big is the president? Also because there are so many types of dinosaurs and their shapes are so strange, we can’t help but wonder how many members there are in this huge family of dinosaurs?
There is also a more important reason, which is why so many dinosaurs that once lived on the earth vigorously and vigorously disappeared from the earth without leaving any traces of them. Descendants have left us an unsolvable mystery. This mystery always inspires us to explore and seek knowledge.
Now we know that the dinosaurs became extinct 65 million years ago.
And at that time, not only were all the various dinosaurs that had ruled the earth for more than 100 million years extinct, but the same tragic fate also befell many other creatures living on the earth's land, oceans and skies. Also extinct in this disaster were marine reptiles such as plesiosaurs, flying reptiles such as pterosaurs, terrestrial reptile relatives of dinosaurs such as leucozoans, and marine invertebrates such as ammonites and belemnites. animals; as for the microphytoplankton in the ocean, the calcareous planktonic foraminifera and the calcareous microphytoplankton were almost wiped out. After this catastrophe, about 50% of the biological genera and almost 75% of the biological species on the earth at that time disappeared from the earth forever.
This is really a great annihilation and catastrophe. As a result of the mass extinction, around 65 million years ago, the face of the biological world on Earth underwent fundamental changes. This mass extinction marked the end of the Mesozoic Era, and the earth's geological history has since entered a new era - the Cenozoic Era.
Scientists have made unremitting efforts to analyze and study all the clues that can be discovered so far, and have proposed various theories to explain this mass extinction phenomenon. But so far, there is still no 100% correct answer to the cause of this mass extinction.
Perhaps, such an answer is waiting for you to find.
Below, we will successively introduce some theories and theories about the causes of the mass extinction of dinosaurs. This will introduce you to some basic background knowledge and hope to provide some inspiration for you to find better explanations. .
Asteroid impact theory
In 1980, at a scientific seminar, American geologist Alvarez and others vividly preached an event based on their research results. In a thrilling story 65 million years ago: On a sunny afternoon, in the tropical shrubs under the scorching sun, many dinosaurs of different types and shapes were walking peacefully by the lake or looking for food in the water as usual. ; At the edge of the forest, a duck-billed dinosaur that had just hatched its eggs was pacing back and forth beside the egg nest; in an open field, a Tyrannosaurus rex was preparing to pounce on a huge Triceratops...
Suddenly, a loud noise that had never been heard before broke the peaceful world. A meteor several kilometers in diameter slammed into the Earth. This collision was huge. An explosion equivalent to the power of tens of thousands of atomic bombs occurred in an instant. This is an unexpected asteroid, and the impact force generated after colliding with the earth can reach the energy generated by the explosion of 1015 tons of TNT explosives. A huge mushroom cloud carrying dust quickly rose up into the sky, then spread out, and finally enveloped the entire earth. Soon, the dinosaurs lost sight of each other because dark clouds covered the sky and there was no sunlight during the day. This horrific situation lasted for a year or two. The photosynthesis of plants is interrupted, so a large number of plants wither and die. Plant-eating vegetarian dinosaurs died one after another as a result. Later, the meat-eating dinosaurs also became extinct due to loss of food.
This story is the essence of the theory that an asteroid hit the earth causing the extinction of the dinosaurs. Later, it was continuously supported by many scientists. Some scientists even believe that the Earth not only experienced a large asteroid impact during this period, but also suffered many smaller, but still seriously life-threatening asteroid impacts. Among them, it can be confirmed that in the Caribbean and Ia in the United States Traces of a planetary impact discovered in Washington.
Evidence for this hypothesis also comes from an amino acid present in 65-million-year-old sediments found around the world. This amino acid contains a large amount of iridium, which is present in large amounts in some celestial bodies, but should not exist at all on the earth. This iridium-rich layer has been discovered in many areas of North America, Europe and Australia. This iridium-containing layer was also discovered in the Gamba region of Tibet, my country a few years ago.
Some scientists believe that this explosion wiped out all dinosaurs. However, some scientists believe that only 70% of dinosaurs became extinct at that time. Some other dinosaur species barely escaped the disaster, but gradually became extinct in the following millions of years. This latter statement is not unreasonable, because some dinosaur bones are still found in the strata formed after this event 65 million years ago. For example, dinosaur remains have been found in the strata above and below 60 million years ago in New Mexico, USA. Triceratops fossils have also been found in the Cenozoic tundra of Alaska. These phenomena seem to indicate that after the big explosion caused by the asteroid impact on the earth, some dinosaurs still struggled to live for millions of years, and finally became extinct one after another because they could not adapt to the new climate and new environment.
The latest theory - large-scale undersea volcanic eruption
The famous Italian physicist Antonio Chicchi recently proposed that the cause of the mass extinction of the dinosaurs was probably a large-scale undersea volcanic eruption. Volcano erupts.
Professor Qijiji believes that at the end of the Cretaceous, a series of large-scale volcanic eruptions occurred under the ocean, which affected the thermal balance of seawater and caused changes in the land climate. Therefore, It affected the survival of animals such as dinosaurs that require large amounts of food to survive. His reason is that the impact of modern submarine volcanic eruptions on the ocean and atmosphere is well known, but the extent of their impact is much smaller than that of submarine volcanic eruptions that occurred 65 million years ago.
Professor Chikichi believes that in the past, the scientific community knew very little about submarine volcanic eruptions.