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Home - Planet - Concepts - Evolution of the planet


ISS Expedition 7 Crew, EOL, NASA
(Image record from Gateway to Astronaut Photography of Earth)

Since its formation, the Earth has gone through several stages in which life has progressively evolved. To understand the magnitude of time of these changes, imagine that the entire history of the Earth was condensed into one year. During January and February, the Earth went through a period of high temperatures which gradually decreased. After chilling, by early March the first primitive single-celled organisms appeared and these were the sole living beings for five months (i.e., 2100 million years). In July the first bacteria and other organisms without nuclei appeared, and life continued with no major complications for three more months (1900 million years). In November, the first molluscs, arthropods, corals, fish and land plants (licopodios, horsetails and ferns) appeared. During the first weeks of December appeared the amphibians and reptiles, while birds and mammals appeared in the last week of December. The first hint of man was on the last day of December, and his civilization only developed in the final minutes of the last day of the year.

Era

Period

Epoch

Duration (million years)

Event

Condensation into one year

Cainozoic

Holocene

0.007

"Civilization"

December´31 23:59 hrs

 

Quaternary

Holocene

0.01

December´31 23:50 hrs

 

Pleistocene

2

December´31 20:00 hrs

 

Tertiary

Pliocene

5

Human kind

December´31

 

Miocene

25

December´29

 

Oligocene

38

December´28

 

Eocene

55

December´27

 

Paleocene

65

December´25

Mesozoic

Cretaceous

 

138

Flowering plants

December´20

Separation of the continents

Jurassic

 

208

Mammals and birds

December´24

Triassic

 

245

December´10

Palaeozoic

Permian

 

290

Reptiles

December´8

Carboniferous

 

360

Amphibians

December´3

Devonian

 

408

Insects & seed bearing plants

November

Silurian

 

438

November

Ordovician

 

505

Terrestrial plants

November

Cambrian

 

590

Arthropods & fish

November

Archaean

Proterozoic

2,500

Bacteria

July

 

3,800

unicellular life

March

 

Archaean

4,600

January


     
 
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