2. Earth Chronology



The Earth was formed around 4.57 billion years ago, during which the solar system was forming too. But it was after 800 million years ago the earth went from liquid to solid, is that the older rock known today has 3.8 billion years.

Around 3.8 billion years ago hastened the emergence of life on earth. The first life forms were born in the warm waters of the sea, under the ultraviolet rays of the sun were small protected by a membrane, able to divide spheres. After about 500 million years around 3.3 billion years ago these primitive living beings start to be capable of photosynthesis.

It took a further 1.3 billion years to the early formation of complex cell which had a cell nucleus surrounded by a membrane, that is, the DNA is separated compartment of the cytoplasm, these living beings are called eukaryotes. And over 1 billion years to form multicellular beings.

Around 1.2 billion years ago initiates mating and results in an explosion in the rate of evolution to reach the formation of the first simple animals around 600 million years ago.

Throughout this period of almost 4 billion years corresponds to geological time(Supereon) called Precambrian flocked where the most important events in Earth history as the beginning of life, the beginning of the movement of tectonic plates and the formation of the atmosphere.

After the Pre-Cambrian Paleozoic era starts which corresponds between 540 million to 245 million years ago. Within this was the Cambrian Period begins where the first annelids, arthropods and mollusks arise .

The fish appeared around 500 million years ago, then it was the turn of terrestrial plants, then insects and seeds to reach the amphibians and reptiles about 300 million years ago and the end of the Paleozoic era.

Dinosaurs arose in the Jurassic period around 230 million years ago. Also emerged in this period the first mammals and birds and Pangaea (only continent to this period) separates into two. Arise early placental mammals, the first flowering plants and the extinction of the dinosaurs about 65 million years ago finalizes the major events of the Mesozoic era.

After this period starts the tropical climate and there were the first large mammals. The first Aegyptopithecus (primitive monkeys) appeared around 33 million years ago and this period is up to 5 million years ago with the changing climate to cold and dry.

Around 1.8 million years ago the first glacial period starts. There were several ice ages over the past million years, occurring with frequency from 40 to 100 thousand years. The last glacial period was between 100,000 and 12,000 years ago .

The first humans (Homo sapiens) appeared around 200,000 years ago.


Resume


Time (years ago) Event
4,500,000,000 Formation of the Earth.
3.800.000.000 Emergence of Life.
3,300,000,000 Beings capable of photosynthesis.
2,000,000,000 Complex cells (eukaryotes).
1,000,000,000 Multicellular beings and sexual reproduction.
600,000,000 Animal Simple.
570.000.000 Arthropods.
500,000,000 Fish.
475,000,000 Terrestrial Plants.
400,000,000 Insects and seeds.
360,000,000 Amphibians.
300,000,000 Reptiles.
230,000,000 Dinosaurs.
200,000,000 Mammals.
150,000,000 Early birds.
100,000,000 Arising flowers.
65,000,000 Dinosaur Extinction.
64,000,000 Tropical climate and early large mammals.
55,000,000 Dogs, elephants, whales, bats.
33,000,000 Aegyptopithecus (The first monkeys).
23,000,000 Cats, camels great apes and bears.
5,300,000 Climate change to cold and dry.
1,800,000 Home of the first glacial period.
200,000 Surge Homo sapiens (early humans).
12,000 End of last glacial period.




Earth Chronology



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