Dinosaurs are ancient creatures thatappeared on the planet about 225 million years ago. For 160 million years, these animals dominated the planet. The extinction period took about 5 million years, and now they are absent for about 65 million years in the animal world. There are many hypotheses about why dinosaurs disappeared. How these animals died out and ceased to exist, we will tell in our article.
Planet Earth has been populated by different species.plants and animals 3 billion years ago. In the process of evolution, plants and animals appear and disappear, and each such process has its own time period and period. Dinosaurs on the planet lived in the Mesozoic era - this is the Triassic, Jurassic and Cretaceous periods.
Первыми простейшими растениями были морские algae, and the first animals are small marine mollusks. The appearance of fish occurred about 500 million years ago. About 370 million years ago, the first animals, amphibians, came to land. Reptiles are a new group of animals that appeared about 300 million years ago. The animals had scaly skin, they could lay eggs and be constantly on land. Next in the chain of evolution were dinosaurs. An extinct animal species gave impetus to the development of such a science as paleontology.
One of the amazing animals that lived onthe planet are dinosaurs. How extinct and how these large animals lived can be judged only by petrified remains. From the fossil remains we can conclude that they were reptiles, like crocodiles, lizards, turtles and snakes. The size of dinosaurs varies in a large range - from tiny to giants. They had four limbs and a tail. Dinosaurs stood and moved on straight limbs, some on their hind legs, others on all four, and others could move both on two and on four limbs. Many dinosaurs have long necks and teeth. Their habitat was significant, but 65 thousand years ago they suddenly died out.
Dinosaurs are divided into two groups:lizardnose and poultry The difference of the groups is in the structure of the pelvic bones. In lizard dinosaurs, the structure of the pelvis is four-rayed, and in birds, the three-beam one. Some species of bird-to-thighs had horns, thorns, shells.
In the 30s of the XIX century were first discoveredfossilized dinosaur remains. Then, archaeologists did not attach special importance to them, and only after some time it became clear that these fossils belong to ancient animals. The very concept of "dinosaur" was introduced by the English zoologist Richard Owen in the middle of the XIX century. From the Latin language "dinosaur" is translated as "scary", "dangerous", "terrible", and from the ancient Greek language - "lizard", "lizard". Since then, interest in these animals is constantly growing. How many years ago did dinosaurs become extinct? The answer to this question is given by science paleontology. Ancient animals are studied by scientists, shot in films, they become heroes of books. And despite such interest, the question of why dinosaurs became extinct, there is no exact answer.
At the end of the Permian period, the formation ofsingle mainland - Pangea. A characteristic feature of this time was global volcanic activity and the disappearance of about 90% of animals. Reptilians adapted best to the new conditions. At the beginning of the Triassic, a group of reptiles called "pelicosaurs" appeared. By the middle of the Triassic, they were replaced by a group of reptiles with the name "terapidy". In parallel with the therapy, a new group of reptiles, the archosaurs, developed. This group of reptiles is the ancestor of all dinosaurs, pliosaurs, crocodilomorphs, ichthyosaurs, placodons and pterosaurs. The following species of reptiles was called the Tekodonts and was adapted to life on land. And from them dinosaurs got their development. The extinct animals adapted well and occupied dominant positions on land, in water and in the air.
During the Triassic period, the following types of dinosaurs existed: celophysis, muszavr and prokommsgnat. Plant dinosaurs evolved and evolved.
The largest animals lived in the Jurassic period. In the Late Jurassic period, land animals began to appear - brachiosaurus, diplodocus, etc.
In the Cretaceous, predatory reptiles began to dominate in the seas and oceans. New types of dinosaurs are emerging.
Меловой период – это период расцвета гигантских raptors, pterodactyls and marine reptiles. At the end of the Cretaceous, the Pangea continent split into Gondwana and Laurasia. The climate on Earth becomes much colder, ice caps are formed at the poles. Flowering plants appear and the number of insects increases.
Всё это привело к вымиранию многих видов растений and animals, including dinosaurs. They did not die out overnight, but if we consider that their domination lasted for 160 million years, their disappearance occurred rather quickly. The causes of the disaster that occurred in the Cretaceous period are still not clear.
But are all dinosaurs extinct?The descendants of ancient reptiles are crocodiles, lizards and birds that exist today. The first birds appeared in the epoch of chalk, and by the end of the epoch they already had developed plumage. When the dinosaurs became extinct, the birds took over the evolution baton.
The fall of the asteroid is one ofcommon versions. The time of its fall coincides with the formation of Chicxulub Crater (Mexico, Yucatan Peninsula). These events occurred about 65 million years ago, during a period when dinosaurs became extinct. It is possible that the fall of the asteroid caused destructive actions, as a result of which a mass extinction of all living things occurred.
The multiple fall hypothesis states thatthe fall of the asteroid occurred several times. In addition to the Chicxulub crater, there is the Shiva crater in the Indian Ocean, which was formed at about the same time. This hypothesis explains why extinction occurred gradually.
There is also a version of a supernova explosion and a comet-to-Earth collision.
There have been significant changes on the planet.a period when dinosaurs began to disappear. How animals have become extinct suggests a theory of changes in average annual and seasonal temperatures. Large individuals need a warm and even climate. Volcanic activity could lead to a change in the composition of the atmosphere and cause a greenhouse effect. A large emission of volcanic ash could provoke a volcanic winter, thereby changing the illumination of the Earth. Significant lowering of sea level, cooling of the ocean, changes in the composition of sea water and a sharp jump in the Earth’s magnetic field could also contribute to the extinction of dinosaurs.
Одна из гипотез этой группы придерживается situations of mass epidemic. It is possible that the dinosaurs could not adapt to the changed vegetation, which caused poisoning. The probability of destruction of eggs and cubs by the first predatory mammals is great. There is also a version that during the ice age the female individuals disappeared. Scientists have proposed another version of the death of dinosaurs - suffocation: in the atmosphere there was a sharp decrease in the amount of oxygen.
Why are dinosaurs gone?How did these ancient animals become extinct? Answers to these questions provide a variety of theories and hypotheses, but none of them answers all questions fully. It is known that the extinction of species began long before the moment of the catastrophe, and the astronomical hypothesis is doubtful in this case. Many theories have no actual data, such as the hypothesis of regression of the World Ocean or changes in the magnetic field. Also, the lack of completeness of paleontological data can give a distorted picture.
Combining hypotheses creates a more visual picture. The hypotheses, complementing each other, provide answers to more questions, and the picture of that time looks more traced and detailed.
The process of evolution is the extinction of the old andthe formation of the new is consistent. And the evolution of dinosaurs until the end of the Cretaceous period occurred naturally. But for some reason, at the end of the Cretaceous period, the old species died out, and the new ones did not appear, and, as a result, there was a complete extinction of this species.
The version of the great extinction is based on the following facts:
According to the scientific world, the following was observedpicture. Developed root system of flowering plants, their best adaptability to the soil quickly replaced other types of vegetation. Insects that fed on flowering plants began to appear, and the insects that had previously appeared began to disappear.
The root system of flowering began to grow andinterfere with soil erosion. The land surface has ceased to erode, and nutrient material has ceased to flow into the oceans. This has led to the depletion of the ocean and the death of algae, which, in turn, are producers of biomass in the ocean. An ecosystem disturbance occurred in the water, causing mass extinction. It is believed that flying lizards are closely linked to the sea, so the chain of extinction has spread to them. On land, they tried to adapt to the green mass. Small mammals and small predators began to appear. This was a threat to the offspring of dinosaurs, as the eggs and cubs of dinosaurs became food for predators that appeared. As a result, conditions were created that are negative for the emergence of new species.
When the dinosaurs became extinct, the Mesozoic era ended, and the active tectonic, climatic, and evolutionary activities ended with it.
Interest in ancient animals is not only inadults, but also in children. Today, the project “Why did the dinosaurs become extinct?” Is included in the program of kindergartens and primary schools. The uniqueness of such activities lies in the fact that the child independently develops cognitive abilities, seeks answers to questions and gains new knowledge. The question of why dinosaurs became extinct is as curious for children as it is for scientists. The interest is primarily due to the fact that there are no these animals on earth today and the exact answer to the question about the reasons for their disappearance has not yet been received.
