How many kinds of dinosaurs are there in the world?

Dinosaurs were a huge family in Mesozoic, and they ruled the animal kingdom at that time.

In time, dinosaurs lived for 65.438+0.6 billion years; In terms of distribution, the footprints are spread all over seven continents. However, most dinosaurs were found in the United States, Mongolia, China, Canada, Britain and Argentina.

There are 64 genera of dinosaurs found in the United States, ranking first in the world. There are 40 genera in Mongolia, 36 genera in China, 3 1 genus in Canada, 26 genera in Britain and 23 genera in Argentina. Animals that are similar to each other belong to the same "genus" in taxonomy, such as cats, tigers, lions and leopards, but they belong to different species. ) Most dinosaurs have only 1 species, and a few dinosaurs have 2 or 3 species. According to statistics, there are 285 dinosaur genera found at present, each with 336.

We don't think this is the actual number of dinosaurs that once lived on the earth. There are still a large number of dinosaur bones buried deep underground, which have not yet been discovered. There are also many dinosaurs who may have walked in the world for nothing and left nothing behind after their death.

Professor dodson of the University of Pennsylvania studied how to estimate the genus number of dinosaurs that have lived on the earth for many years. He estimated that 900- 1200 dinosaurs once lived on the earth. But only part of it was discovered. But after the discovery, few people explored and studied it carefully.

According to dodson, the number of dinosaurs we have discovered is about 1/3-? . This shows that the task before dinosaur experts is still quite huge, and the discovery and research of dinosaurs have a long way to go. With the deepening of dinosaur research, new dinosaur genera and species will be discovered continuously. As long as the remains of many unknown dinosaurs on the list are still there, they will not be buried, and they will be famous all over the world forever.

Dinosaur kingdom (full text)

Hello, everyone, I am honored and happy. Today, I have the opportunity to talk with my classmates at the University of Chemical Technology about how to find dinosaurs and how to study them. Everyone is doing chemistry and engineering. How can they be related to dinosaurs? In fact, sometimes the study of dinosaurs can really be linked with chemistry. For example, when we study ancient dinosaurs, we sometimes want to know about the living environment of this dinosaur at that time. So we have a research direction, that is, for example, to do this geochemical thing, measure some rare earth elements or trace elements, and restore the environment at that time through these elements, so as to understand what the era when dinosaurs lived at that time was like, whether it was hot, cold, dry or wet. There are some other aspects, such as when we study dinosaur eggs, when we study other aspects, sometimes we can use chemical methods. Of course, I won't talk about this chemical method here today because I don't do it myself. What should I do? That's what I did. In a popular saying, I hope to find more and more dinosaurs, and then sort out the relationship between these dinosaurs, such as who and who are brothers, or father-son relationship. By understanding this relationship, we can restore this evolutionary tree of life, in other words, during its long period of existence of about1.700 million years, by restoring this evolutionary tree, we can understand a series of many important life topics, such as the origin of this bird. As we all know, this bird is now one of the largest vertebrate groups we know, and we know about 10 thousand species. But how did these 10 thousand beautiful birds, very lovely birds with different shapes, originate and evolve at first? Then we should start with dinosaur fossils. Of course, dinosaurs had many other problems besides the origin of birds. Next,

Dinosaurs were first discovered about 160 years later. You see the big bone stick on it, which is the earliest reported dinosaur fossil, when this dinosaur fossil was discovered. Because people didn't know much about biological evolution at that time, they began to describe it as a kind of ancient giant ape-man leg bone fossil. Of course, it seems ridiculous now, right? Obviously, there can't be such a big ape. Anyway, from this fossil, people began to find many other dinosaur fossils. For example, the following dinosaur fossil, let's take a look at this long-toothed dinosaur fossil, which is the first dinosaur named Megalodon in the world. What about the gentleman next to the tooth? His name is Owen. He is an English naturalist. He was the first person to systematically study dinosaurs and the first person to name them. Many dinosaur fossils were found, but we didn't know which group they belonged to. Later, Owen grouped all dinosaur fossils together. He said that these animals were called dinosaurs. Since he named dinosaurs, it should be said that dinosaurs have been discovered very, very much. According to incomplete statistics, there are about 1 100 genera, and these 1 100 genera are distributed in all continents as we know. So from now on, it means that the distribution range and time of dinosaurs are very extensive. Let's take a look at this picture, which is a spiral recovery picture of life evolution. Dinosaurs lived for a long time from the Middle Triassic to the Late Cretaceous, about 65.438+0.7 billion years. This is a picture of the evolution of vertebrate life. You can see all kinds of creatures, including this fish, snake and crocodile. At the bottom, you can see a dinosaur with a straight tail, which shows that among the animals we know now, dinosaurs are closely related to birds and are a branch of birds. That's what we know about dinosaurs. For example, it is an animal that lived from Triassic to Cretaceous10.7 billion years ago, and its genetic relationship is closest to birds, which is its position in the field of biology. So how do we know this knowledge? It was obtained by studying dinosaur fossils. In these different types of rocks, we look for dinosaur fossils, dig dinosaur fossils, and then recover through this dinosaur fossil. I was just talking about the position of dinosaurs in the evolution of life. We can learn about the ancient world through dinosaurs.

This is a dinosaur named Lu Fenglong, which was discovered in Yunnan in the early days of liberation. Let's look at this picture. Above is a skeleton, and below is a dinosaur fossil in the rock. At that time, it was buried. Let's look at this fossil. It is very beautiful. This dinosaur is called Mamen Xilong. This dragon is very long, about 23 meters long, and its neck should be said to be beyond your imagination. So sometimes people will think, with such a long neck, how can it stand up, will it break its neck or something? But we have many fossils to prove that this animal is alive and well. This is a restored picture of a fossil, a dinosaur fossil found in Xinjiang. You see, this dinosaur fossil is a bit like a dog, but it has nothing to do with dogs. It is true that some dinosaur fossils are all kinds, but the size and shape are very different. This shows that dinosaurs were a very big family. As I told you at the beginning, 1 100 genera have been reported so far. Of course, it should be said that there are only more than 300 genera, but each genus contains many species, indicating that the dinosaur family is very large. So when we do this work, the first thing we need to know is that we have discovered new fossils and how many kinds of dinosaurs there are. Then we need to do a very important job, which is to connect these different kinds of dinosaurs, that is to say, classify them and see what relationship they have, such as the relationship between brothers or uncles, or perhaps straighten out the relationship between them. Here is a small life evolutionary tree restored by different kinds of dinosaurs, called a branching tree, which shows that this dinosaur has two different categories, that is, there is a sauropod above and a bird-buttock below, and these two categories contain different subclasses. Among them, you can see the third one. This dinosaur is very, very interesting. Why do you say that? One of the dinosaurs became a bird, which later evolved and radiated into a huge family of birds we see today, with more than 10 thousand species. I just talked about restoring its kinship, which is the work of systematics. We can also do a lot of other work, such as paleontology, such as studying dinosaurs, whether they are warm-blooded animals, for example, we all know that crocodiles and lizards are cold-blooded animals, and they are lazy, every day. But what about dinosaurs? We found some evidence that it was different. It is different from typical reptiles, and it is very close to this kind of birds and mammals. So it has a high metabolic rate and moves quickly.

Let me give you a few examples to illustrate how dinosaur research has enriched our understanding of the ancient world and the life world and promoted our understanding of evolution. Look at this picture. Look at this animal. It looks strange. It has a big belly, but its mouth is a little sharp like a bird. It also has feathers. This dinosaur is called Kamakura Age. You can see that its claws are very sharp, like daggers, indicating that it is a carnivore. But if you look at other features of this dragon, such as the teeth on its mouth and some specific structures of its mouth, what about this dragon? It's not like a carnivore. And being like a very docile herbivore means that this animal is a contradictory combination. Because of its contradictory characteristics, which family does everyone say this Kamakura belongs to? Is it a bird-buttock family or a lizard-buttock family? Recently, by studying the fossils in China, we have made this problem clear. That is to say, although this dinosaur looks strange, we have good evidence that it is closely related to birds, that is, it is closely related to birds. This is another kind of dinosaur called Liaoning Dragon. This dinosaur is very small, only 50 cm, very small, but it is not the same as a dinosaur more than 20 meters long. It is an adult dinosaur, and this dinosaur is a juvenile dinosaur. It suffered misfortune shortly after its birth, and then it died and formed a fossil. What's the significance of this dinosaur? In the initial research, everyone thought that dinosaurs walked upright, that is, dinosaurs were different from other reptiles, such as lizards and crocodiles. Everyone saw its hand crawling forward. But dinosaurs are different. Dinosaurs are more like birds and mammals. Their limbs are under their bodies and they walk upright. The lizard next to it looks like it is crawling. Their two postures are completely different, and it is generally believed that dinosaurs walked upright. However, we found some fossil evidence of this Liaoning dragon. It seems to crawl like other reptiles, such as lizards or crocodiles. Why did I say it was a reptile? This deck is preserved in its abdomen, and judging from the preserved state of this dinosaur, it is buried in the same place, which means that its deck is so big that its legs can't stand up straight and it can only stretch sideways, so it is a reptile, which is a very intuitive phenomenon. This animal is not funny to everyone. There is a dinosaur here and a rabbit here. At first glance, everyone can see that they have similarities. What are the similarities? They are front teeth, ugly, but also cute. Indeed, in this dinosaur world, it has many strange things, that is to say, the dinosaur family is a strange family, and many of its forms are often unexpected. Before this fossil was discovered, I did say that I had studied dinosaurs for so long that I never imagined that it would grow like this. Even after I saw the fossil, I wondered if there was something wrong with it and what caused it. But there were such dinosaurs in ancient times. Why did I put this photo here? It tells us another problem, that is, by studying this dinosaur, you will find some evidence, for example, its teeth have a good grinding surface, which shows that this dinosaur is a herbivore, but from the evolutionary tree of life just now, this dinosaur's ancestor was a carnivore, that is, it changed from a carnivorous dinosaur to a herbivorous dinosaur, just like the giant panda we know now, it ate bamboo. But the ancestors of giant pandas also ate meat, so in different branches of vertebrates, such as mammals and dinosaurs, we will find an amazing phenomenon of convergence and evolution.

Let me tell you another example in scientific research, called the origin of birds, which is also the most interesting and actually the most confusing question. As we all know, the origin of birds, I just mentioned that there are many different birds in the bird world, so if we trace back to the source, these birds were all a long time ago, and now if we predict, it will be about 65.438+0.5 billion, or 65.438+0.6 billion, or even 65.438+0.7 billion. This hypothesis is the earliest. This man is Huxley. He is a British naturalist. He found that birds and dinosaurs looked alike in the19th century. He asked if there was a relationship between the two animals. So this comrade with glasses in the lower right corner, he is a professor at Yale University. His name is Ostrom. He studied the earliest bird called Archaeopteryx in the world and some small dinosaurs that ate meat in North America. Later, he came to a conclusion. That is to say, birds evolved from dinosaurs, but if I put these two pictures together, no one will accept this phenomenon. How did such an ugly dinosaur become such a beautiful bird? But it is a very good hypothesis from a scientific point of view, and it has been confirmed by many scientists. We study the origin of birds, not from this beautiful bird, but from the fossils of the earliest birds in ancient times. You can see that the fossil in the lower left corner is archaeopteryx, the oldest bird fossil found in Germany, and the fossil restoration map in the upper right corner is a dinosaur found in the United States, called Deinonychus. If you compare the bone morphology of these two animals, you will find that the two animals are strikingly similar, that is, you can't deny that they are related. On the left, you can see the skeleton contrast between a dinosaur and a bird. If you count them bit by bit, you will find that dinosaurs and birds have many similarities, at least 100 species, and many of them are unique to birds and dinosaurs and can't be found in other animals, so this bone form provides good evidence for the close genetic relationship between birds and dinosaurs. Some white fossils can be seen in the fossils above, and then there is a round thing below, which is a dinosaur skeleton lying on a nest of dinosaur eggs. What's the significance of this fossil? In other words, by studying the fossils of the dinosaur bones and eggs, scientists found that the dinosaur was hatching eggs when it died. I don't know if anyone from the countryside has seen an old hen hatch eggs, but if you compare other animals, you will find that this hatching behavior is a good feature of birds, that is, birds can hatch eggs. Like other animals, such as turtles, you may not have a chance to watch turtles lay eggs, but if you read popular science books, you will know that, for example, turtles can swim, swim to an island and dig a small hole. The discovery of this fossil shows that dinosaurs, like birds, hatched eggs, which means that birds inherited this hatching behavior from their dinosaur ancestors. And this fossil below, this round dinosaur egg, you may have heard of this dinosaur egg. By studying the dinosaur egg, such as cutting it open and looking at its structure, we will find that the structure of dinosaur egg is very similar to that of bird egg. That is to say, in the past 30 years, many scientists have found many good fossil evidences from the United States, such as North America, Argentina, many places in South America, Madagascar from Africa, Mongolia from Asia, including China. From this skeleton, from this behavior, from this microstructure, it is proved that dinosaurs and birds are close relatives, in other words, the hypothesis that birds originated from dinosaurs has been well proved before the middle of last century 1990 s. Through the study of these fossils, we have enough reason to believe that a dinosaur became the first bird, and then this huge bird family was formed by this first bird, probably 65.438+600 million years ago.

The research on the origin of birds seems to be over, but it is not. In fact, from the perspective of popular science, I will tell you that this hypothesis has been well demonstrated before the last century1990s. So what should we do now? Are we unemployed now? That's not true. In fact, there are many things to do in this evolutionary process. What are we going to do? For example, although we know that dinosaurs became birds, we don't know the process. What is involved in this process? The first question, such as which dinosaur became a bird, after we know which dinosaur became a bird, we will accurately restore this history and see how the main characteristics of birds evolved. For example, if we know that this dinosaur became a bird, then if we have an accurate evolutionary history, we will find out, for example, how did birds fly? When did you fly? When did you learn it? How did it learn? For example, there are feathers like birds. As we all know, feathers are unique to birds. What can I say if you catch any animal now, even you? With your eyes closed, if you touch feathers, it's okay to be a bird, and you won't say it's a mouse. Because it is different from a feather, you wouldn't say it is a turtle, because its feather is a very unique thing, so how did this feather evolve? This is what we young people and many other scientists in the world are doing. This is a simple picture. Let's look at many different dinosaurs, and this is just a small part of them. That is to say, it is found that these dinosaurs may be closely related to birds, but which one is the closest? We don't know. This is a branch diagram of the process of dinosaurs becoming birds, in other words, the evolutionary tree of life. For example, we try to find out which dinosaurs became birds. You can see that this bird is located here. It is closely related to two kinds of dinosaurs, one is called odontosaurus, and the other is called Long Ben, which are the following two kinds. These two species are collectively called deinonychus. That is to say, birds are the closest to these two dinosaurs. From 65438 to 0990 in the last century, many very important fossils were found in our country, which provided good fossil evidence for the study of the two major problems of flight and feathers I just mentioned. Before we found this fossil evidence, people knew little about these two problems. For example, in this assembly site, the feathers and flight of birds must have been formed before this, so at which point? Where did it form in this tree? How is it formed? We need fossil evidence to answer this question.

This is the first dinosaur fossil found in Liaoning, our country, which is very important. When you look at it, I won't tell you it's a fossil. You think it's a Chinese painting or a beautiful work of art, but it's really a fossil and it's beautifully preserved. You can see from beginning to end. The most interesting thing is that you see a lot of this black thing on its back. This black thing looks a bit like our hair in form. It is this hair, at that time. Everyone guessed that it was a primitive feather. However, there are also many people who oppose it. Soon, another interesting fossil was discovered. You can see that this fossil is called the tail feather dragon. This gesture is a gesture of birds, called courtship. Express your love. But why is this fossil interesting? As you can see from its tail, it is called tail feather dragon, tail feather dragon. Why is it called tail feather dragon? Its tail looks like a fan. It looks the same as today's bird feathers Although it is exactly the same as the feathers of modern birds, you can even see feathers on its forelimbs, but it is a dinosaur, it is not a bird. This is another fossil, which is not as beautiful as the first two fossils, but also has feathers. This is its restoration map. This is not as affectionate as that just now. This dragon is fierce, with a big mouth and sharp teeth. This dinosaur is called Chinese Bird Dragon. You can see that its forelimbs can flap like the wings of a bird. Although it has feathers and can flap its wings, it is still a dinosaur. This is another kind of dinosaur. It doesn't jump around on the ground like those dinosaurs just now. It ran to a tree. This dinosaur is called Microraptor, and there is a Microraptor in the distance. Everyone saw that it seemed to spread its wings and learn to fly down.

You can't see this kind of Microraptor in the picture. In fact, this dinosaur is a very small dinosaur. The size of Microraptor is only 50 cm from beginning to end, which is the smallest dinosaur found in the world. Some small dinosaurs have been found in the past, but none of them are so small. Even broke through a critical point. What critical point? In other words, all dinosaurs found in the past were bigger than the earliest bird archaeopteryx, but Microraptor was the first dinosaur and smaller than archaeopteryx. This little individual is of great significance. What's the point? That is, a bird must learn to fly and be light. Otherwise, you said that elephants must learn to fly. I find it difficult. It must be light enough to fly into the blue sky. Microraptor meets this requirement in this respect. We found that Microraptor not only has this significance in the research process, but also is very small, which is valuable for the study of the origin of flight. We also found some other interesting phenomena. For example, the hind feet of Microraptor are similar in structure and shape to some arboreal birds, that is, birds living in trees, that is, they are not particularly similar, that is, close. At that time, we inferred from this evidence that this dinosaur was very small and light, and its legs and hind feet were very similar in structure to arboreal birds. So is it also a dinosaur living in a tree? If so, it is the first known dinosaur, supported by fossil evidence, living in trees. So if this inference is correct, it provides a good and good evidence for the origin of bird flight. At that time, when we published this article, we also wrote this view in it and made some arguments. Of course, after the publication of the article, it should be said that the impact is not particularly great. Why? Because of this, our evidence is not very strong, and many other scientists have other evidence. Say, your evidence is not strong enough to change this Microraptor, it is an arboreal animal, and you can come to this conclusion. You mentioned this possibility just now, but it is not enough to convince us that this is the scientific process. But we are still very happy. After all, this is a start, and it should be said that it provides a good start for solving this problem. And I'm telling you in private here. It is very important that we have found good evidence recently. This time, our evidence is very strong, much stronger than what I just said about Microraptor, which provides very, very good evidence that this dinosaur is arboreal. Therefore, the study of Microraptor and dinosaurs similar to Microraptor provides evidence for the origin of flight, and it should be said that the origin of flight has taken a big step forward.

In fact, there is another interesting and embarrassing thing about the study of Microraptor. How can I put it? One thing, that is to say, the study of Microraptor is closely related to an event called "Pirate Bird", which is a world-famous event. How did this happen at that time? It is at 1999 that there is a magazine called National Geographic. I wonder if you have read this magazine. It is a world-famous magazine, a popular science magazine. It should be said that it is the largest popular science magazine in the world and the most successful magazine. As for this magazine, some people say it is part of the American spirit. It is not easy for Americans to do this. It made a big mistake in 1999, which should be said to be the most serious mistake in its history of 100 years. What mistake?

It was1June 1999, 10/October, and the famous National Geographic magazine published an article, reporting an early bird fossil called "ancient bird". It is very interesting that this bird has a dinosaur's tail. At that time, "ancient pirate birds" were called "missing links" between dinosaurs and birds. The report said that the front of the "ancient bird" is a very progressive bird with strong flying ability. But the second half of its body is a typical dinosaur tail. So the dinosaur became a bird and learned to fly. This is the best evidence that birds originated from dinosaurs. For a time, many media around the world rushed to report.

In June, I was on a business trip in western Liaoning at 5438+0999 1 1, and I was very lucky to find the specimen of Microraptor. At that time, I really didn't think that Microraptor had anything to do with "ancient birds", but after we took this specimen back, we observed and compared it and suddenly found a small probability event. I think everyone is studying science and engineering and knows what a small probability event is. It is a part of the specimen of Microraptor that we found, and it is actually the other half of the American "ancient pirate bird" specimen. As we all know, there are many fossils in Liaoning and many places in China. Many fossils have been smuggled or lost abroad for various reasons. But in fact, these two specimens, one on the other side of the earth and the other on the other side of the earth, were discovered by accident. I just saw that, and then I went back to Liaoning and happened to find this piece, which was broken in half by a specimen. Then by comparing the two specimens, we found that the tail of Archaeopteryx was not its own tail, but the tail of Microraptor, which was wrong. Of course, this sense of security is deliberately put on by some people. As for his ideas and purposes, we won't talk about it. Indeed, I will talk about this process. This small probability event happened, and I found the other half of the fossil. Later, I told National Geographic that you don't need to promote the "ancient bird" anymore, because now I have found the fossil evidence that the "ancient bird" is fake, and if you continue to promote it, you may make more mistakes.

After the disclosure of the "Liaoning ancient bird" incident, it caused an uproar in the international community. National Geographic immediately sent someone to investigate the whole incident. And in June 2000, 10, I reported in an article how this error happened and how to correct it. The United States returned this "Liaoning ancient bird" specimen to China free of charge, and now it is kept in the Herbarium of the Institute of Paleontology, China Academy of Sciences.

Why are we talking about this? I don't have enough time to talk about it today, but if you are interested, you will see this report. In the process of this matter, you will see the relationship between science and humanities, and the relationship between ordinary people and scientists. What kind of connection is this feeling? In other words, you will find that science is a very humanized process. Ordinary people have shortcomings, and so do scientists. But in this process, the most important thing for a scientist is that on the one hand, you are an ordinary person, but on the other hand, you should always remember that you are a scientist. As a scientist, the most important thing is to face up to the evidence and dare to examine it from a scientific point of view.

By studying the beautiful fossils I just mentioned, we can also study another problem, that is, the origin of flight. You can see that these two pictures are two hypotheses about the origin of flight. Dinosaurs became birds. We have no doubt now. Everyone admits this, but people argue about another problem, that is, how did dinosaurs fly when they became birds? Most people think that dinosaurs ran very fast because they lived on the ground. So obviously, it must have flown into the sky when it ran. It is difficult for many people to intuitively accept the assumption that it flew into the sky while running. This Johnson ran 100 meter and didn't see him in the sky for eight seconds. Isn't he still running on the ground? Admittedly, this assumption is hard to be intuitively accepted, that is, running to the sky. Simplified characters, of course. In fact, it has many processes. Although it is hard to accept intuitively, if you want to study this evidence as a researcher, we will talk about fossil evidence most. After studying its structural changes, you will find that it really seems that this fossil evidence supports the hypothesis that it may become a flying animal when it runs. Everyone studies the posture of many dinosaurs and studies it, which is the conclusion drawn from dinosaur fossils.

For example, its hind legs, its walking speed and the changes of its forelimbs will show that it was indeed a good running animal in the process of evolution from dinosaurs to birds, and its many anatomical structures also support that it was also a good running animal before becoming birds, even the most primitive birds, Archaeopteryx, a better running animal, so from the evidence of many fossils, most fossils really support this hypothesis, that is, dinosaurs. But some people still think that it is hard for me to accept this kind of rush to the sky. I am still willing to accept another point of view. What's the point? That's arboreal, that is to say, when the dinosaur climbed to the tree first and then lived in the middle of the tree, for example, when it jumped from tree to tree, there was a jump. In the process of jumping, it has a process of, for example, landing and landing. During this landing process, it gradually became more and more capable. It patted its forelimbs and put this landing process.