In ancient times, there used to be a group of strange creatures-dinosaurs. They ruled the earth, lived for nearly 15 thousand years, and finally died out magically. Everything we know about dinosaurs today comes from dinosaur fossils.
There are many kinds of dinosaurs, and their shapes and habits are quite different. Among them, the big one can be as big as dozens of elephants combined; Small, but almost like a chicken. As far as food habits are concerned, dinosaurs have mild vegetarians and fierce carnivores, and there are omnivorous dinosaurs that eat both vegetarian and vegetarian foods.
early discovery
Although dinosaur fossils have existed on the earth for tens of millions of years, it was not until the nineteenth century that people knew that such a strange animal had existed on the earth. The first dinosaur fossil was discovered by an English doctor named gideon algernon. Dr mantel usually has a hobby of collecting rocks and fossils. In A.D. 1820, he and his wife Marian discovered some huge teeth embedded in rocks. Dr mantel has never seen such big teeth. When he found more bones nearby, he began to study these unusual discoveries seriously. After some efforts, Dr. Mantel came to the conclusion that these teeth and bones should belong to a huge reptile. He named this unknown animal Iguanodon, and its original scientific name was Iguanodon's teeth. Soon, the bones of two giant reptiles were found in Britain, which were named Ban Long and Forest Dragon respectively. It was not until A.D. 184 1 year that these giant reptiles got their official names. At that time, an outstanding scientist, Sir richard owen, named them dinosaurs, whose scientific name means terrible lizards. Since then, the upsurge of dinosaur research has been unveiled, and scientists all over the world have become interested in digging dinosaurs.
Scenes of the dinosaur era
Dinosaurs lived on the earth10.5 billion years ago. During such a long time, many changes have taken place in the environment of the earth. The Pangu continent, which was originally connected as a whole, gradually drifted and split into the familiar form. After these continents drifted around the world, the climate and environment also changed. Land mass drift, coupled with climate change, has caused great changes in plant species on the earth. But because these changes are gradually formed in a very long time, the animals growing in them can still adapt well. In the early dinosaur era, the dwarf shrubs composed of ferns were the main vegetation on the earth. Later, tall coniferous forests and low cycad jungles replaced ferns and became the main plant landscapes on the earth. Soon after, the first flowering plants appeared, and the plant landscape on the earth changed greatly. Many plants and flowers that dinosaurs lived on at that time still live on the earth today.
Big monsters and small brains
Many people think that dinosaurs are giants as tall as giant trees. In fact, many dinosaurs were petite and not as high as human knees. Among the terrestrial creatures that have appeared on the earth, the herbivorous sauropod dinosaur is the largest, and Brachiosaurus is one of the best. Brachiosaurus weighed about 70 tons and was 22 meters long. Its height is 12 meters, which is equivalent to the height of four floors! Recently, people have unearthed dinosaur fossils larger than brachiosaurus-dragon and super dragon. According to calculation, the super dragon is one third bigger than Brachiosaurus, and its weight before death may be as heavy as twenty elephants! Compared with these gentle behemoths, the beautiful jaw dragon is much more agile and light. Megalodon is a small carnivorous dinosaur that may not weigh as much as a cat.
Long-necked monster
Starting from this page, you will see an eight-page giant dinosaur. This is Liang Long, one of the biggest dinosaurs that once lived on the earth. Liang Long and Mamenxilong on the right belong to sauropods. Liang Long has a very long neck and tail. By contrast, his head is very small. Although it seems strange, it fits their way of life. The long neck enabled Liang Long to eat the leaves at the top of the tree, such as the common conifer leaves at that time. The small head made it easy for Liang Long to dive into the bushes and eat plants that other dinosaurs seldom ate. This foraging skill can only be achieved through Liang Long's strong, light, soft and flexible neck. When Liang Long has eaten all the food in an area, they will look around for new food together. When Liang Long was attacked by carnivorous dinosaurs, their strong trunks and long tails like whips were their best defensive weapons.
Dinosaur's feeding habits
Many people think dinosaurs are terrible carnivores. In fact, many dinosaurs were gentle herbivores, just shuttling between trees and tearing leaves at the treetops to eat. Some dinosaurs, like humans, were omnivores that ate both meat and plants. As for carnivorous dinosaurs, they don't just eat dinosaurs. Anything that moves, such as insects and birds, is their prey. From the remains of dinosaur fossils, we can know many eating habits of dinosaurs before their death. One of the most important clues comes from the shape and arrangement of dinosaur jawbones and teeth. In addition, the shape of the whole dinosaur skeleton can also provide some clues. For example, carnivorous dinosaurs usually had a big head and a short and powerful neck to tear off the meat of their prey and eat it. On the other hand, most herbivorous dinosaurs had long necks, which made it easier for them to feed on the leaves at the top of trees.
Ancient footprints
Dinosaurs not only left fossils as evidence of survival, but also left footprints on the surface. These footprints were left when dinosaurs walked through the soft and muddy banks in search of food and water. Later, these footprints were dried and hardened by the sun, and rain and flood carried a lot of sediment to bury them. Slowly, they became fossils. These fossils are called trace fossils because they do not belong to animal bodies. Trace fossils provide a lot of information about dinosaur behavior. For example, among a large group of identical footprints, smaller footprints are often found. Scientists speculate that these small footprints may have been left by small dinosaurs protected in the middle when dinosaurs moved in groups.
Myths and legends
When the bones of dinosaurs were first discovered, it was hard to believe that such creatures ever existed on the earth. At that time, giant dinosaurs were almost equivalent to terrible monsters in people's minds. Because people know little about dinosaurs, they have many wrong ideas. For example; When remodeling dinosaurs, misspell the bones or confuse the bones of dinosaurs with those of other animals. Also, most people think that dinosaurs are huge, bulky and stupid animals, and they are on the verge of extinction because they can't adapt to their living environment. In fact, these ideas are completely wrong! Dinosaurs can be said to be the most elegant and shrewd creatures that have ever appeared on earth. They have survived for10.50 billion years, which is 150 times of the current human survival time on the earth!
The end of the dinosaur era
At the end of Cretaceous, dinosaurs became less and less, and finally all disappeared. At the same time, the landform of the earth has also changed. Because of the expansion of the seabed, Pangu continent was divided into several pieces. The rising sea level has turned many low-lying areas where dinosaurs lived into Wang Yang. Many kinds of marine animals have also become extinct. In addition, the warm climate in the past year has become more changeable or seasonal. The species of plants have also changed, and flowering plants have become more and more important. The extinction of dinosaurs just made another group of creatures on the earth-mammals rise.
Looking for dinosaurs
How did scientists find dinosaur remains? Dinosaur remains must be covered with sand or soft mud, which will be fossilized by sand for a long time, so dinosaur fossils usually only appear in sedimentary rocks. Many dinosaur fossils were accidentally discovered by construction workers or mining workers while digging the ground; Others are excavated by fossil lovers in places that may be rich in fossils. Large-scale scientific exploration is much more planned, and people will study the possible places in detail before starting to dig. No matter which way dinosaur fossils are discovered, it is necessary to make detailed preparations in advance to successfully discover fossils. Moreover, when excavating, we must carefully record the correct position of fossils and choose appropriate tools to ensure that fossils can be taken out of rocks intact and sent to the laboratory.
The mystery of dinosaur extinction
Until about 70 million years ago, dinosaurs ruled the earth. However, less than 5 million years later, that is, 65 million years ago, they were all extinct. Moreover, the whole extinction process is likely to occur in just a few months. Why this happened is still a mystery. Scientists have put forward various theories to explain the mystery of extinction, such as the theory of meteorite hitting the earth, the theory of large-scale volcanic eruption, the theory of disease or food poisoning and so on. But any theory to explain the extinction of dinosaurs must be able to explain why many other animal populations died out at the same time besides dinosaurs. Scientists are still studying the secret of dinosaur extinction.
Be born, grow up
Can you imagine what giant dinosaurs looked like in infancy, adolescence and adulthood? According to some recent discoveries, experts have been able to piece together the life of dinosaurs in their infancy. Now we know that mother dinosaur laid her eggs in a hole in the surface of the earth. In some dinosaur eggs, even small dinosaur fossils that have not yet hatched have been found. Small dinosaur bones were also found in the nests of a group of hadrosaurs, and their teeth showed signs of wear, which indicated that the mother dinosaur would bring food back to feed the small dinosaurs in the nests. Little dinosaurs may grow very fast; Moreover, some dinosaurs, such as Ceratosaurus, changed the proportion of all parts of their bodies as they grew up. In addition, when a group of sauropods move together, small dinosaurs will surround the team to protect young children.
Eggs and nests
The dinosaur eggs discovered one after another can confirm that dinosaurs, like modern reptiles and birds, also produced hard-shell eggs. Some egg fossils even found small dinosaur bones that were not hatched! Sometimes the remains of large dinosaurs are found near the nest where dinosaur eggs are found. It can be seen that little dinosaurs, like birds, will instinctively stay in their nests no matter what happens to their parents. Some dinosaur nests are close to each other, so experts speculate that dinosaurs may have social habits. Surprisingly, the dinosaur egg is not as big as expected. If the size of dinosaur eggs is directly proportional to the size of dinosaurs, then the eggshell will be so thick that little dinosaurs can't hatch; Moreover, it is impossible to get enough oxygen into the egg to provide breathing for the little dinosaur.
timetable
It's incredible to think of it; Animals and plants have lived on the earth for 700 million years! During this time, countless creatures appeared and disappeared. The first dinosaur appeared in the late Triassic, about 2. 1 billion years ago. At this time, the land masses of the earth are still connected together, called Pangea. After dinosaurs appeared, they ruled the earth until the late Cretaceous 64 million years ago. During the reign of dinosaurs, great changes have taken place on the earth: land drift, sea level change, climate change, and many creatures have disappeared. Careful observation of fossils in the early and late dinosaur era and at the same time as dinosaurs shows that some creatures have not changed at all, but some have changed greatly.