In addition to the gradual disappearance of species, our planet has experienced numerous extinctions of species diversity in the past 540 million years (MY), a score of crises more or less intensively and successfully. Most are occupied by large volcanic eruptions caused by the fall. Some Dell Inspiron 1525 Battery died en masse which led to the disappearance of the species most alive. But every time the extinction led to the explosion of a continuation of life, richer, especially in new ways not experienced before. Mass extinctions play a role in the diversification of life forms.

The great mass extinction of species that forever changed his life on earth.

Before the mass extinction - MA 438: Ordovician-Silurian

70% of marine species, including famous trilobites disappear.

Causes

The causes are still unclear, but carry a high level of under sea ice.

Another hypothesis by Brian Thomas, an astrophysicist (Washburn University) is increased: gamma radiation to reach the earth.

After the mass extinction - MA 365: Devon-Carboniferous

Eliminating a number of extinction, 70% of the species are. Again, it is mainly of marine species that are interested: corals, brachiopods, benthic organisms. Plants and arthropods are little affected.

Causes

The causes are still unclear, but carry a high level of under sea ice.

Thirdly, the mass extinctions: - 252.6 BUT: the crisis of the Permian-Triassic

252,600,000 years ago the Earth's largest mass extinction ever recorded: the Permian-Triassic crisis (1). Over 90% of the then existing species disappeared suddenly, especially in the oceans, the biosphere with a ruined take 1-30 years to find a biodiversity comparable to that of the crisis. For this scenario, the "destruction of the environment (2) of the rule" to Dell Inspiron 1545 Battery support

Permian-Triassic extinction crisis is probably the worst ever mass on Earth known to disappear for more than 95% of all species, both on land and the oceans. This mass extinction took place gradually over a period 10 million years, followed by a sharp acceleration of 5 million years. The biosphere is destroyed, we talk about environmental degradation (destruction of (natural or anthropogenic) the Dell Inspiron 1720 Battery systematic and total ecosystem).

Many sedimentary and geochemical record of serious pollution in the Lower Triassic (5 million years after the mass extinction) confirm that the carbon cycle of the oceans acidic abnormal carbon dioxide, oxygen and carbon-enriched sulphides (CNRS, 09 / 2011) was used .

10 to 30 million years before finding a biodiversity comparable to the crisis. If life was on the brink of extinction, extinction, new forms of life that continues to diversify in a way that is incomparable.

This crisis marks the end of the Paleozoic, Mesozoic or Paleozoic and early or Mesozoic.

Causes

The causes of this extinction is due to the impact of a comet, or more likely a major episode of volcanism and intense Siberian traps appear to testify. In all cases the species suppressed due to high temperatures and a lack of oxygen.

Mass extinction Fourth: - MA 200: Triassic-Jurassic

This kills 20% of marine species, most diapsids (reptiles, birds), amphibians and glorious past. In all, half the planet's biodiversity disappears. However, this crisis has the reign of the dinosaurs on Earth.

Causes

The causes are not clearly identified, and several hypotheses have been raised.

With the breakup of Pangaea, huge volcanic eruptions, which lasted at least 600 000 years occurred in the Mid-Atlantic magmatic province.

This period also corresponds to an increase in levels of carbon dioxide and a massive release of methane. In fact, researchers at Utrecht University found that at least 12 000 gigatonnes of carbon (as methane) released into the atmosphere from 20 000-40 000 years. This would have led to global Dell Inspiron 1521 Battery warming (Bits of Science, 07/2011).

Finally, among other possible causes have been a meteorite.

Five mass extinction - 65 MA: Cretaceous-Tertiary, the end of the dinosaurs

All the kingdoms combined, almost six and eighteen species have disappeared, including the large dinosaurs, including the famous dinosaurs. Dell Vostro 1700 Battery Insects and small mammals, by contrast held up well. Almost all marine plankton, an important link in the chain of food of animal origin and also disappeared. It seems that animals weighing more than 20-25 kg survived, except for the crocodiles.

Causes

Various Dell Vostro 1500 Battery  theories more or less controversial proposed for this mass extinction, meteor showers, explosive volcanism epidemic larger poisonous for plants containing alkaloids, the inversion of the magnetic field of the Earth, cooling ...

Two main hypotheses are favored: the fall of a meteorite and an important volcanism. Recent developments in this area looking at the fall of a meteorite with a diameter of six miles in an area in the Yucatan peninsula in northwestern Mexico. A meteorite crater, Dell Inspiron 6000 Battery called "the Chicxulub crater" was discovered in 1991, is about 200 km in diameter. When this effect, very large amounts of sulfur, soot and dust dispersed in air in minutes, allowing disturbance events such as global dimming and global cooling, while the extinction of 70 % currently.

In addition, the disaster at a time when volcanic activity was intense on the ground saw the Deccan Traps in India.

Currently, the Dell Inspiron 6400 Battery loss of biodiversity and environmental changes associated with them faster than any other time in history. Many animal and plant populations are declining, both in terms of number of people, geographical coverage, or both. The loss of species is part of the natural history of the Earth. However, human activity is accelerating the pace of extinction is at least 100 times the natural rate of extinction, a rate that Dell Latitude D820 Battery increases, some biologists such as EO Wilson talks about 1000 times!

The current extinction is caused by human activity, is comparable to a major crisis as organic in 2050, while 25-50% of species have disappeared.

Thus, the role and flourished almost all human societies, the great battle. But millions of years required for biological diversity after a mass extinction to be covered.

And human society, that this mass extinction has begun permanently seal the fate of humanity: we are both the cause and the victims of the sixth mass extinction ...