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 Automatic translationAutomatic translation Category: Earth
Updated March 14, 2015
  Biodiversity during the Phanerozoic

Image : Evolution of the number of genera (set of species) during the Phanerozoic, according to a 2005 study by Robert A. Rohde & Richard A. Muller (Department of Physics and Lawrence Berkeley Laboratory). The diversity of life seems to fluctuate during the Phanerozoic, this curve shows the apparent changes in marine biodiversity throughout the 542 million years of the Phanerozoic. There are 3 eras in the Phanerozoic, the primary era (542-250 my), the Mesozoic era (250-65 my) and Tertiary (65 my to now). These eras are marked by great mass extinctions, especially one that took place there are 250 my and that took place there are 65 ma. Since the last mass extinction there are 65 my, life has never been more diverse than today.

    
  Biodiversity during the Phanerozoic

Image : Intensity of mass extinctions in the Phanerozoic. The five major disasters in the history of the Earth occurred at the end of the Cretaceous (End K) at the end of the Triassic (End Tr) at the end of the Permian (End P) in the late Devonian (Late D) and at the end of the Ordovician (End O). Credit image : GNU Free Documentation License.

Major biological crisis Families Genera Species
       
Ordovician
(≈ −450 million years)

22%

55%

85%
Devonian
(≈ −370 million years)

22%

50%

75%
Permian - Triassic
(≈ −250 million years)

55%

80%

95%
Triassic - Jurassic
(≈ −205 million years)

22%

50%

75%
Cretaceous - Tertiary
(≈ −65 million years)

15%

45%

75%

Table : The five major disasters in recent Earth history (last 540 ma). These figures are probably biased, but they have the merit of bringing out the Permian-Triassic crisis like the one that was the most devastating and the Cretaceous-Tertiary crisis, the best known and yet least deadly. Successions of volcanic eruptions, ones after the others would they have had an impact on the evolution of biodiversity by participating in mass extinctions?

geological times

Image : Geological aeons, of the Hadean to Phanerozoic, the last 540 million years are the best dated. credit astronoo.

The astronomical unit created in 1958, is the distance unit used to measure distances to objects in the solar system, this distance is equal to the distance from Earth to the Sun. The value of the astronomical unit is exactly 149 597 870 700 m, at its General Assembly held in Beijing from 20 to 31 August 2012, the International Astronomical Union (IAU) has adopted a new definition of the astronomical unit, unit of length used by astronomers around the world to express the dimensions of the solar system and estellar systems. One will retain approximately 150 million kilometers. A light year is approximately 63,242 AU. Mercury: 0.38 AU, Venus 0.72 AU, Earth: 1.00 AU, March: 1.52 AU, Asteroid Belt: 2 to 3.5 AU, Jupiter 5.21 AU, Saturn : 9.54 AU, Uranus: 19.18 AU, Neptune: 30.11 AU, Kuiper Belt: 30 to 55 AU, the Oort Cloud: 50 000 AU. An eon is a very long period of geological time, arbitrary length. The history of the Earth, its formation to the present, is divided into four aeons. The first three (Hadean, Archean, Proterozoic) cover the first 4 billion years of the Earth history. They are sometimes combined into one superéon named "Precambrian". The fourth is the Phanerozoic eon, which began there 542 million years, which is the era of the appearance of small animals, fish and plants on Earth.
           
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