Dinosaurs: how extinct? When did dinosaurs die out?

Dinosaurs are ancient creatures that appeared on the planet about 225 million years ago. For 160 million years, these animals dominated the planet. The disappearance period took about 5 million years, and for about 65 million years in the animal world, they are absent. There are many hypotheses why the dinosaurs disappeared. How these animals died out and ceased to exist, we will tell in our article.

The appearance of dinosaurs

The planet Earth was inhabited by various species of 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 era of the Mesozoic - this Triassic, Jurassic and Cretaceous periods.

The first protozoa were algae, and the first animals - small marine mollusks. The appearance of fish occurred about 500 million years ago. Approximately 370 million years ago, the first animals - amphibians - emerged on land. Reptiles are a new group of animals that appeared about 300 million years ago. Animals had scaly skin, they could lay eggs and constantly be on land. Next in the chain of evolution were dinosaurs. The extinct species of animals gave impetus to the development of such a science as paleontology.

Description of dinosaurs

Some of the amazing animals that lived on the planet are dinosaurs. How extinct and how these big animals lived, one can judge only by petrified remains. According to fossil remains, it can be concluded that they were reptiles, like crocodiles, lizards, turtles and snakes. The size of dinosaurs varies in a wide range - from tiny to giants. They possessed four limbs and a tail. Dinosaurs stood and moved on straight limbs, some on hind legs, others on all four, others could move on both the two and four limbs. Many dinosaurs had long necks and teeth. Their habitat was significant, but 65 thousand years ago they suddenly died out.

Dinosaurs are divided into two groups: lizhorotazovye and ptitsetazovye. The difference between groups is in the structure of the pelvic bones. In the scaphiotic dinosaurs, the structure of the pelvis is four-rayed, and in the case of poultry plants, it is three-beam. Some species of ptitsetazovyh had horns, spines, armor.

The emergence of interest in dinosaurs

In the 30-ies of the XIX century for the first time were found the fossilized remains of dinosaurs. Then archaeologists did not attach much importance to them and only after a while 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 "terrible", "dangerous", "terrible", and from the ancient Greek language - "lizard", "lizard". Since then, interest in these animals is constantly growing. How many years ago dinosaurs died out? The answer to this question is given by the science of paleontology. Ancient animals are studied by scientists, filmed in films, they become heroes of books. And despite such interest, the question of why the dinosaurs died out, there is no exact answer.

The Age of Dinosaurs

At the end of the Permian period, the formation of a single continent - Pangea. A characteristic feature of this time was the global volcanic activity and the disappearance of about 90% of the animals. The best adapted to new conditions were reptiles. At the beginning of the Triassic, a group of reptiles called "pelicosaurus" appeared. By the middle of the Triassic period, they were replaced by a group of reptiles called "terapsids". In parallel with the therapists, a new group of reptiles - arhosaurs - developed. This group of reptiles is the ancestor of all dinosaurs, pliosaurs, crocodilomorphs, ichthyosaurs, placodonts and pterosaurs. The next species of reptiles was called tekodonts and was adapted to life on land. And already from them the dinosaurs have developed. Extinct animals adapted well and took dominant positions on land, in water and in air.

During the Triassic period, the following dinosaur species existed : cotophysis, muszavr and procomsognat. Developed and evolved vegetable dinosaurs.

The largest animals lived in the Jurassic period. In the Late Jurassic period, land animals began to appear-the brachiosaurus, diplodocus, and others.

In the Cretaceous period, predatory reptiles began to predominate in the seas and oceans. There are new types of dinosaurs.

End of an era

The Cretaceous period is the period of the heyday of giant pangolins, aerial pterodectors and marine reptiles. At the end of the Cretaceous, the Pangea continent is 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.

All this led to the extinction of many species of plants and animals, including dinosaurs. They did not die out overnight, but if you consider that their domination lasted 160 million years, then their disappearance happened quite quickly. The causes of the catastrophe that occurred during the Cretaceous period are still unclear.

But did all dinosaurs become extinct? Descendants of ancient reptiles are existing crocodiles, lizards and birds. The first birds appeared in the era of the chalk, and by the end of the era they already had developed feathers. When the dinosaurs died out, the birds adopted the baton of evolution.

Astrophysical hypotheses of extinction

The fall of the asteroid is one of the most widespread versions. The time of its fall coincides with the formation of the Chicxulub Crater (Mexico, Yucatán Peninsula). These events occurred about 65 million years ago, at a time when dinosaurs died out. Perhaps the fall of the asteroid entailed destructive actions, as a result of which a mass extinction of all living things occurred.

The multiple fall hypothesis says that the fall of the asteroid occurred several times. In addition to the Chixulub crater, there is a Shiva crater in the Indian Ocean, which was formed around the same time. This hypothesis explains why extinction occurred gradually.

There is also a version of a supernova explosion and a collision of a comet with the Earth.

Geological and climatic hypotheses of extinction

On the planet there were significant changes in the period when the dinosaurs began to disappear. How animals died out, suggests a theory of changing 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 release of volcanic ash could provoke a volcanic winter, thereby changing the illumination of the Earth. A significant decrease in sea level, cooling of the ocean, a change in the composition of sea water and a sharp jump in the Earth's magnetic field could also contribute to the extinction of dinosaurs.

Evolutionary-biological hypotheses of extinction

One of the hypotheses of this group adheres to the situation of the emergence of a mass epidemic. It is possible that the dinosaurs could not adapt to the changed vegetation, which resulted in poisoning. The probability of destruction of eggs and cubs by the first predatory mammals is great. Still there is a version that during the glacial period women 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 did the dinosaurs disappear?

Why did the dinosaurs disappear? How did these ancient animals die ? The answers to these questions are given by various theories and hypotheses, but none of them answers all the questions in full. It is known that the extinction of species began long before the time of the catastrophe, and the astronomical hypothesis in this case is doubtful. Many theories lack factual data, such as the hypothesis of a regression of the World Ocean or a change in the magnetic field. Also, the lack of completeness of paleontological data can give a distorted picture.

The combination of hypotheses forms a more graphic picture. Hypotheses, complementing each other, provide answers to more questions, and the picture of that time looks more detailed and detailed.

The process of evolution - the extinction of the old and the formation of a new one - are consistent. And the process of evolution of dinosaurs until the end of the Cretaceous period occurred naturally. But for some reason at the end of the Cretaceous the old species died out, but new ones did not appear, and as a result, the species completely died out.

From the point of view of paleontology

The version of the great extinction is based on the following facts:

1. The appearance of flowering plants.
2. Gradual climate change caused by continental drift.

According to the scientific world, the following picture was observed. The developed root system of flowering plants, their better adaptability to soils, quickly replaced other types of vegetation. Insects that fed on flowering plants began to appear, and previously appeared insects began to disappear.

The root system of flowering plants began to expand and hinder the process of soil erosion. The surface of the land stopped blurring, and the nutrient material ceased to flow into the oceans. This led to the depletion of the ocean and the death of algae, which, in turn, are producers of biomass in the ocean. In the water there was a disturbance of the ecosystem, which caused a mass extinction. It is believed that the flying lizards are closely connected with the sea, so the chain of extinction spread to them. On land, they tried to adapt to the green mass. Small mammals and predators of small size began to appear. This was a threat to the offspring of dinosaurs, as eggs and young dinosaurs became a food for emerging predators. As a result, conditions were created that were negative for the emergence of new species.

When the dinosaurs died out, the Mesozoic era ended, and active tectonic, climatic and evolutionary activity ended with it.

Children and dinosaurs

Interest in ancient animals is not only in adults, but also in children. Today the project "Why did dinosaurs die out?" 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 receives new knowledge. The question of why the dinosaurs died out is as curious for children as it is for scientists. The interest is primarily due to the fact that these animals are not on earth today and the exact answer to the question of the reasons for their disappearance has not yet been received.