Предлагаем восстановить, заказать, купить диплом Вуза в любом городе России. Только настоящий бланк ГОЗНАК с гарантией.
Viewings: 5561Life on Earth is always struggling for survival. Animals live in constant stress, to get enough food and adapt to the environment.
Some animals that are ill know how to adapt to changes struggling, starving, cease to multiply and eventually die out. Throughout the history of our planet lives acquired new forms, which were then tested for survival.
Why was the mass extinction?
When the climate and environment fluctuated significantly, many living beings which could not adapt to the new conditions, died. Mass extinctions have occurred more than once. This phenomenon forms of life had disappeared completely, leaving no fossils, no descendants. Mass extinctions have occurred since the beginning of the origin of life on Earth.
All the animals who today live on the planet, are only the descendants of those beings who were lucky and were able to adapt to the changed world. We offer you to look into the past and learn about the 10 most serious mass disappearance of flora and fauna on the planet.
1) Edukacijsko mass extinction
During Adikari complex creatures for the first time began to get shape. Tiny bacteria evolved into more complex life forms - the eukaryotes, some of which began to form groups in order to increase your chances to find food and to avoid becoming someone else's prey. Most of these creatures did not leave anything because they did not possess the skeleton. They were soft-bodied and are fully decomposed after death without saving in fossils.
The first primitive creatures
Only in very rare cases beings times Educare could reach us in fossils, for example, if the animal were left lying in the soft mud, which quickly hardened, so it was the imprint. These few fossils tell us about the presence in the seas and oceans of the strange creatures that resembled modern worms, sponges and jellyfish.
These animals are dependent on oxygen, as we are. The level of oxygen in the atmosphere began to fall 542 million years ago. Then he began the mass extinction. More than 50 percent of living beings of the planet died. A huge number of dead bodies of living beings rotted into fossil fuels.
The reason why decreased oxygen levels not yet known scientists. However, this extinction were positive consequences: it provided the impetus for the Cambrian explosion, unexpected diversity complicated creatures that were as simple worms.
2) the Cambrian-Ordovician extinction
During the Cambrian period, life on Earth has flourished. The living beings that appeared at the time Educare remained largely unchanged for millions of years, but after the onset of Cambrian life forms began to develop quite rapidly evolved a great many unseen beings. Exotic crustaceans and trilobites have become dominant. Molluscs and giant marine arthropods similar to insects filled the sea. These creatures had a hard outer shell, which they have come down to us in the form of fossils.
Ice age caused extinction
Life on Earth is flourishing, while unexpectedly (from a geological point of view) 40 percent of all living things on the planet suddenly disappeared 488 million years ago. Those who managed to survive, difficulty coping with harsh environmental conditions. That led to mass extinction of this period, scientists do not know.
According to one of the theories in this period took place the ice age, rather, the coldest part of it. The last 11 thousand years on Earth dominates the so-called "Interglacial". Extreme temperature decrease, probably, led to the death of a great number of species. It is this mass extinction marked the border between the end of the Cambrian and Ordovician.
3) Ordovician-Silurian extinction
Life on Earth began to flourish again in the period called the Ordovician. Nautiloid (primitive octopus), trilobites, corals, sea stars, eels and fish gelatine sponge filled the oceans. Plants were gradually selected on the land. Gradually life became more complicated.
The second force mass extinction of species
443 million years ago, more than 60 percent of life on Earth died as a result of the second power of mass extinction in history. This extinction was associated with abrupt onset of the ice age, resulting in decreased levels of carbon dioxide. A large part of the waters which were home to a huge number of living beings, is frozen or covered with ice caps and glaciers, which led to lower levels of oxygen.
It is believed that the flash of gamma-rays from space has destroyed the ozone layer and on the surface of the planet began to break free of ultraviolet radiation of the Sun, which destroyed much of plants. Fortunately, some people managed to survive, but to fully recover took another planet 300 million years.
4) Mass extinction Lau
After Ordovician-Silurian extinction began during the Silurian period. Life again was restored on the planet and in this time have evolved first sharks and bony fish, most of which are very similar to modern. Mosses and small steel plants grow freely on land along the coast, and some arthropods evolved into spiders and centipedes, which are adapted to dry air and began to dwell among the plants along the coast.
Giant sea Scorpions are very diverse, began to dominate the trilobites. 420 million years ago there was a sudden change of climate, which disappeared about 30 percent of species. Atmospheric gases has changed in proportions that for many animals became uninhabitable and toxic. The causes of this event is unknown.
Life on the planet were struggling to the end Selenskogo period and prior to the period of Devon, when evolution was able to produce completely different models of life, which began to thrive and feel.
5) Mass extinction of late Devonian
In the Devonian period certain fish species appeared fins that they were used as limbs, allowing them to crawl on land. These living beings, eventually evolved into reptiles and amphibians. In the seas giant coral reefs were filled with fish, including sharks, and other marine life, some of which were fed by the trilobites.
The trilobites have ceased to occupy the dominant position in the water for the first time in 100 million years, since then, as he had appeared. Actually sharks of this period were so successful that they did not need especially to change. Some modern sharks look exactly the same as their ancestors Devonian period.
Land plants were given seeds and reached a high diversity. Evolved more complex species of plants on land, and for the first time in the history of the Earth appeared soil. Appeared strange forest with an 8-meter mushrooms that today we can see only in sci-Fi movies. However, 374 million years ago, 75 percent of all of this amazing animals became extinct. This again was connected with the change of the composition of the atmosphere, probably because of the intense volcanic activity, or because of a meteorite.
6) the Disappearance of tropical forests of the Carboniferous period
After Devon was followed by a period carbon (Carboniferous). Several terrestrial animals by this time have developed the ability to lay eggs on land, which enabled them to dwell anywhere, and not depend on bodies of water in the coastal areas where they have laid eggs, as it is doing today turtles. Came flying insects. Sharks enjoyed its Golden age and some trilobites that survived the last extinction, began to meet less and less.
Coniferous trees Carbon reached us
Appeared giant trees and a huge tropical forests began to cover most of the land our planet, increasing the atmospheric concentrations of oxygen to 35 percent. For comparison, today our atmosphere contains only 21 percent oxygen. Coniferous trees Carbon has remained virtually unchanged today.
305 million years ago was short, but the sudden ice age caused by the reduction of carbon dioxide to a record level. Large forest began to die, and with them many land animals. At the time, disappeared about 10 percent of all living things on the planet. The trees began to rot, compaction, which led eventually to the formation of deposits of coal, therefore, this period was called Coal.
7) Mass Permian extinction
After he had gone a giant tropical forests, on the land remained the most successful animals that laid eggs. They quickly took the dominant position, while other species are still recovering. There appeared a lot of variety of reptiles and synapsida that resembled mammals and was their ancestors.
The worst catastrophe of the Earth
252 million years ago there was an accident, of which the Earth has never seen before or after. Treasondeposits followed the fall of a meteorite or volcanic activity, which has changed the composition of the atmosphere radically. From 90 to 99 percent of all living creatures of the Earth perished. It is the biggest mass extinction in the history of the planet.
If to compare with the extinction of species, which is caused by human activity, in our history, we are also guilty of the death of only 1 thousand species of animals. Because in today's world, there are about 8 million known species, then died out just 0.01 percent. This is nothing compared to what happened during the Mass Permian extinction.
8) the Triassic-Jurassic extinction
After the devastation of the Permian reptiles again took the dominant position. Appeared dinosaurs. Dinosaurs were not taken the leading position and while in size were not more horses. Their descendants became famous and terrifying creatures, which we all know.
The beginning of the death of the dinosaurs
All large dinosaurs, Tyrannosaurus, the stegosaurs, Triceratops and a giant dinosaurs zauropody with long necks, appeared in the Jurassic and Cretaceous periods. 250 million years ago, 65 percent of creatures of the Triassic period became extinct, including all major terrestrial animals. Many dinosaurs survived thanks to small dimensions.
Most mass extinctions lasted about one million years, but this extinction occurred just 10 thousand years. Probably it was caused by intense volcanic eruptions, which are highlighted in the atmosphere of a huge amount of carbon dioxide or sulfur dioxide, leading to climate change.
9) the Mass extinction of the late Jurassic period
During the Jurassic giant marine reptiles such as the famous plesiosaurus, dominated the oceans. Pterosaurs were the host of heaven, and dinosaurs earth. The stegosaurs, long diplomacy and predatory dinosaurs allosaur become widespread. Coniferous, cikatove trees, Ginkgo and ferns accounted for the majority of forest vegetation. Smaller dinosaurs got feathers began to appear first birds.
The death of the inhabitants of the seabed
200 million years ago to about 20 percent of all those creatures suddenly disappeared from the fossil record, mainly marine species. Shellfish and corals were widespread, however, as a result of this event, they had almost disappeared. Those few who managed to survive, have gradually settled by the sea in the next few million years. This mass extinction is not particularly affected land animals disappeared only a few dinosaurs.
The reason of extinction of marine animals is a subject of controversy in the scientific world, but according to a leading theory, there is a possibility that the tectonic plates of the oceans are a bit low, making the oceans deeper. A large part of the marine life was adapted to the shallow water, and therefore began to die, having moved away from the surface.
10) the Cretaceous-tertiary extinction
This is the most famous mass extinction of species. After the end of the Jurassic period, the dinosaur had continued to grow and evolve into the next period - Chalk. These animals have become appearance, which is familiar to almost all modern children. But most importantly, it is in the Cretaceous period, life finally regained strength after the earlier of the Ordovician-Silurian extinction.
The death of the dinosaurs
The number of species is only now for the first time reached the level of the Ordovician period, which was the place for 300 million years to the Cretaceous. Synapsida eventually evolved into small, like rodents creatures, which were the first true mammals.
65 million years ago, a huge meteorite struck the Earth in the area of modern Mexico, destroying the atmosphere and causing terrible global warming, resulting disappeared 75 percent of living beings.
This meteorite contained a high concentration of iridium and rare element on Earth. All terrestrial species that existed 65 million years ago, contain a thin layer of iridium, which remained in the result of a meteorite. Managed to survive only some small reptiles and mammals. Mammals replaced dinosaurs and became the dominant land animals on the planet.
You are reading news Топ 10 массовых вымираний if You liked the article Топ 10 массовых вымираний, prokomentiruet her.