Dinosaurs are the largest animals in the world. It appeared about 2. 1 100 million years ago and finally magically became extinct. Everything we know about dinosaurs today comes from dinosaur fossils.
There are many kinds of dinosaurs. According to the shape of their skeletal fossils, they can be divided into ornithosaurus and sauropods, and according to their tooth fossils, they can also be divided into carnivores and herbivores. Dinosaurs are not only varied, but also amazing in shape. Some of them fly in the sky, some swim in the water, and some crawl on land. A big one can be as big as dozens of elephants combined; Small, but almost like a chicken.
So far, the largest dinosaur we have found is Zhenlong, which is 39 to 52 meters long! The height can reach 18 meters! ! The weight reaches 130 tons! ! ! If such a behemoth walks on the night of January, every time its giant feet step on the ground, it will make the earth tremble, just like an earthquake, so it is called "Zhenlong".
Dinosaurs ruled the earth for a long time until they suddenly became extinct 65 million years ago. Scientists have been arguing endlessly about the reasons for the extinction of dinosaurs. There are two main viewpoints: one is "small celestial body impact theory". 65 million years ago, a meteorite hit the earth, which led to volcanic eruption and great changes in the earth's climate, and finally made dinosaurs extinct on the earth; The other is "volcanic eruption theory", that is, volcanic groups erupt, spewing lava slurry, and then the world of ice and snow comes, leading to the extinction of dinosaurs.
As for the real reason for the extinction of dinosaurs, there is no answer yet, which will be a mystery in human hearts. Let's explore the secrets of science! Come back to answer this secret later!
The dinosaur's self-report
Hello, everyone, I believe you will not feel strange to me. I am a prehistoric animal-dinosaur who lived about 65 million years ago.
Although our dinosaur fossils have existed on the earth for tens of millions of years, it was not until the nineteenth century that people knew that there was such a strange animal on the earth. Speaking of the origin of the name "dinosaur", there is still a story! 1820, an English doctor named Mantel first discovered the fossils of our teeth and knew that they might belong to a giant reptile named Iguanodon. 184 1 year, Sir richard owen, an outstanding scientist at that time, officially named us dinosaurs, whose scientific name means scary lizards, and the upsurge of studying dinosaurs was thus unveiled.
There are many kinds of dinosaurs, about 900 kinds. So our bodies and habits are very different. Among them, the largest can reach 45 meters, and dozens of elephants add up: the smallest is less than one meter, which is similar to a chicken. As far as eating habits are concerned, we dinosaurs have docile vegetarians, ferocious carnivores, and omnivorous dinosaurs who eat both vegetarian and vegetarian foods. 65 million years ago, the earth was ruled and dominated by us, and there were dinosaurs in the sky, land and sea. In order to better understand us, let me tell you something about some dinosaurs with characteristics in our dinosaur family!
People used to think that dinosaurs, like reptiles today, laid eggs all their lives and then walked away, no matter what happened to their children. Actually, it's not. There is a kind of dinosaur whose young dragons were raised by their parents in their nests. When they went out to line up, the big dinosaurs were on both sides, and the small dinosaurs were protected in the middle of the line. It can lay 25 eggs at a time. These 25 little dinosaurs eat hundreds of pounds of fresh plants every day. Large dinosaurs had to tirelessly look for food everywhere. How hard it is. Therefore, scientists have given them a very humanized name: the female dragon. By the Red Deer River in Canada, there is a dinosaur named Albertosaurus. Compared with ordinary dinosaurs, their bodies are smaller, but they are more terrible to other animals. Because they run very fast, it is estimated that they can reach a speed of more than 30 kilometers per hour in a short distance. The terrible thing about Albertosaurus is that its mouth is very big and full of sharp teeth, which can break hard bones, not to mention the thick skin of other dinosaurs. In addition, their front paws are as sharp as eagles, and it is difficult for any animal to escape bad luck when caught. You should go to the dinosaur park.
We dinosaurs, like other creatures, will go through the process of emergence, prosperity and extinction, which is the inevitable law of biological evolution. But the sudden disappearance of our dinosaurs from the earth is still a mystery, and this mystery is still waiting for you to solve! !
Why did dinosaurs become extinct?
One day 65 million years ago, the green jungle was bathed in the scorching sun and was peaceful. Some dinosaurs gathered near the jungle, some of them chased each other, some were quietly devouring fresh leaves, some triceratops snuggled together to rest, and two hadrosaurs walked around the nest, carefully guarding their unborn babies. In the shadow of the jungle not far away, there is a Tyrannosaurus Rex. Its fierce eyes stare at everything in front of it, looking for opportunities to pounce on the target it is interested in.
Suddenly, a dull thunder broke the peace of the jungle. Hadrosaurs first craned their necks warily, and their voices grew louder and louder. It shook the earth and brought an ominous omen. Triceratops jumped up quickly, but it was too late. The earth is shaking, like a mountain of boulders falling from the sky, surrounded by smoke, clouds of smoke rising from the ground. In an instant, the boundary between heaven and earth disappeared, darkness was everywhere, and the world seemed to come to an end. Within a few days, the earth's surface was completely covered with smoke and dust, covering the sky, the temperature plummeted and darkness enveloped the earth. Without sunshine, plants withered, a large number of dinosaurs suffocated and died, and those who survived by luck fell down one after another because there was no food to eat. The earth is full of dinosaur bodies and bones.
This is the story that scientists told us about the extinction of dinosaurs. At that time, many asteroids hit the earth. The strong impact not only left a crater with a diameter of about 200 kilometers on the earth's surface, but also caused the high temperature and high pressure generated during the impact to vaporize the material, thus making the earth's surface constantly full of dust, leading to a large number of animal and plant deaths and the disintegration of the biological chain. Dinosaurs died out after this sudden disaster. A few dinosaurs may have narrowly escaped a temporary disaster, but they won't last long, because the environment on which they live has been completely destroyed and it will take a long time to recover, and only death awaits them.
The theory that asteroids hit the earth is not a woven myth, and the enrichment of iridium in the stratum is an important scientific basis. It turns out that the content of iridium on the earth is very small, only concentrated in the depths of the core. Where does a small amount of iridium in the formation come from? Through in-depth study, scientists believe that these iridium should come from cosmic dust. In the late 1970s, a high concentration of iridium was found in the clay layer on the Cretaceous-Tertiary boundary in Italy, which coincided with the extinction time of dinosaurs. Subsequently, during this period, the iridium content in the strata was found to be abnormal in many parts of the world, so the hypothesis that whisperd hit the earth and made iridium exist in the strata was proved. According to this hypothesis, geologists began to look for iridium anomalies around the world, and more and more evidence supported this hypothesis. It has become an acceptable theory that asteroids hit the earth and led to the extinction of dinosaurs. Information from astronomical observations shows that more than 2,200 asteroids have been discovered and named in the solar system, and there is no doubt that they have the opportunity to "visit" the Earth. It is also calculated that when an asteroid falls to the earth, the energy released by the impact is equivalent to hundreds of atomic bombs and hydrogen bombs exploding at the same time, and hundreds of tons of soil and dust may be thrown into the air, leaving the earth in darkness and disorder for at least several months or even longer. It seems that the extinction of dinosaurs is an act of god.
There are many other hypotheses about the extinction of dinosaurs. For example, the "Nemesis Hypothesis", that is, the theory of comet impact. It is believed that when a comet in the solar system is disturbed by the gravity of a companion star, it will produce thousands of "storms", and some of these "storms" will spread to the earth, so that the earth will suffer a trauma every once in a while (about 26-30 million years), and dinosaurs will die because of this continuous blow. Related to the hypothesis that the universe brings disaster, there are supernova explosion theory and solar flare hypothesis. In recent years, some new hypotheses have emerged, such as the "canceration theory" that dinosaurs were caused by the penetration of neutrinos in outer space, and dinosaurs were probably collectively extinct after suffering from various cancers. All these hypotheses are dinosaur extinction theories that emphasize extraterrestrial factors, but the causes of dinosaur extinction can not be ignored. The earth entered the late Mesozoic, and the living environment changed greatly. The development of dinosaurs has reached its limit and it can't adapt well to new conditions. Although dinosaurs ruled for a while, with the arrival of a new era, they had to give way to emerging mammals.