The whole history of the Earth is divided into 2 main periods - cryptozoa and the Phanerozoic. Cryptococci period is counted from the moment Vozniknovenie our planet (4.6 billion years ago). This period saw the formation of the earth's crust, ocean, began living organisms. Cryptozoic is conventionally divided into archaea, or archeozoic, and the Proterozoic. The duration of each of them is about 2 billion years.
When archeozoic on our planet has favorable conditions for the emergence and development of life. Life on Earth appeared not later than 3, 5 billion years ago. The first living organisms were the simplest structure. But as a result of natural selection was surviving organisms better adapted to their environment. This led to more complex life forms.
At the beginning of the Proterozoic period in the waters of the World ocean lived algae and the first multicellular organisms: sponges, coelenterates, mollusks, and worms.
The Phanerozoic is divided into the Paleozoic, Mesozoic and Cenozoic era.
In the period of the Paleozoic spill occurred seas, and a single continental block fell apart, which was later developed into the modern continents. At the end of the Paleozoic died out many primitive plants and animals.
For the period of the Mesozoic era flora and fauna became more progressive and varied forms.
The Cenozoic era was an important step in the development of the Earth. In this period of insectivorous animals evolved primates, from which people and the earth's surface gradually became modern shape.
