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What are AD

What are the era

The whole history of the Earth's life is divided into long segments, which are called eras.

Each is distinguished by certain changes in the geography and climate, as well as significant developments in the plant and animal world.

archean era

This era has its origins from the time of formationEarth, as a planet, and lasts about 1 billion. Years. It was during this period arose the first inhabitants of our planet - the anaerobic bacteria. Then came photosynthesis - the most important stage in the evolution of life, led to the division of the organic world on the flora and fauna. At the end of this period, there were multicellular and sexual process, which increased the possibility of adaptation to environmental conditions.

The first photosynthetic organisms were blue-green algae and cyanobacteria pre-nuclear.

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proterozoic era

Great for the duration of the development phaseEarth, which lasted about 2 billion. Years. When it appeared the first simple organisms on our planet. During this period, bacteria and algae are at their dawn, formed the largest iron ore deposits of organic origin.

Living organisms are multicellular(Archeocyathids, sponges), their organs are formed. They change the shape and composition of the Earth's crust, forming the biosphere and contribute to the accumulation of oxygen in the atmosphere. At the end of the Proterozoic era appear annelids. All life processes of this period took place in the ocean.

Palaeozoic

This segment represented 6 periods: Cambridge, Ordovician, Silurian, Devonian, Carboniferous and Permian. In the animal world there are and develop a variety of fish species, including sharks, appear and then become extinct corals. A little later comes the age of amphibians - grasshoppers, beetles, reptiles. The flora of this era is represented by the development of thick forests along the river banks, consisting of tree ferns and conifers first.

Geography and climate of this period permanentlychange. Glaciation at the end of the Ordovician period, replaced by warming and mild climate. The Devonian torrential rains alternating with drought in the Carboniferous glaciation occurs, which is then followed by warming, heat and dry climate. This diversity is due to climatic conditions changing positions of continents and the greatest disasters.

As a result, there are various mountain peaks, including the Ural mountain range and the Himalayas.

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The Mesozoic era

The Mesozoic Era is represented by Triassic, Jurassic andCretaceous period. In the animal world, dinosaurs and various reptiles are the dominant group, there are frogs, land and sea turtles, new species of shrimp and coral. Later appear precursors of modern insects and birds. At the end of an era comes the extinction of the dinosaurs and pterosaurs.

The climate becomes milder and the entire landbecome overgrown vegetation different: the precursors of today's pines and cypresses, the first flowering plants. It is establishing the relationship between plants and insects. The Mesozoic Era is a split continents and removing them from each other, formed the island. Is formed and expands the Atlantic Ocean, the sea flooded huge areas of land.

Cainozoic era

The modern era, which began 66 million. years ago. During this period, there are angiosperms plants, birds, mammals and people. In the middle age there are already representatives of the main groups of the kingdoms of nature. Develop shrubs and herbs, there are meadows and steppes. Forming the main types of ecosystems in nature and agrocnosises. There is the use of nature by man to satisfy his needs. As a result of human influence changed the organic world and nature.

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