FIVE MASSIVE EXTINCTIONS IN THE EARTH.

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The location of the volcanoes, known as the Siberian stairs, is now in the north of of Russia, concerning the Siberian city Tura, and also they include Yakutsk, Norilsk and Irkutsk. They cover an area of little less than two million square kilometres, a major size that that of Europe. The plumes of ash of the volcanoes travelled up to the regions that now the Arctic of Canada occupies, where they found a few caps of coal ashes. The studies have suggested that the volcanoes liberated 3 trillions of tons of carbon, sufficient to unleash a massive climate change. The eruptions also caused acid rain and issued sufficient halogens as to create a hole in the cap of ozone, it affirms. The toxic ash, especially, could have been the final blow

They died 90 % of all the species; 96 % of the marine species (53 % of the biological marine families, 84 % of the marine kinds) and approximately 70 % of the terrestrial species (including plants, insects and vertebrates), between them, 98 % of the crinoideos, 78 % of the braquiópodos, 76 % of the dashing ones, 71 % of the cephalopods, 21 family of reptiles and 6 of amphibians, besides great numbers of insects, trees and microbes. The acquaintances trilobites disappeared forever with this extinction in mass. After the catastrophe only it would survive 10 % of the present species at the end of the Permian one.

4. Fourth massive extinction: between Triassic - Jurassic period

It corresponds with the massive extinction of the Triassic -Jurassic one, the third most catastrophic. It affected in an important way the life in the surface and in the oceans of the Earth, disappearing near 20 % of the biological marine families (though the majority of these groups recover in the Jurassic one) what is equivalent to approximately 75 % of the marine invertebrates. Several groups went out of arcosaurios, of which only they survived three: Crocodilia, Dinosauria and Pterosauria. Also stands out the total extinction of the not mammalian sinápsidos as the Thrinaxodon. The reason was probably volcanic. This stage finished with the majority of the terápsidos, the conodontos, the rincosaurios and the arqueosauros, the reptiles placodontos and mamiferoides, big amphibious … The only marine reptiles that survived were the ictiosauros and plesiosauros.

The reasons of this extinction are not known, since there are many hypotheses, but none stops "fitting" with everything what happened. The liberation of so big number of ecological niches left the scene prepared for the dinosaurs, which were beginning his domain in the Earth up to the following paragraph … they have proposed diverse explanations for this event, but in all of them ropes stay.

5. Fifth massive extinction: between the Cretaceous Tertiary period

The fifth massive extinction, which took place between the periods Cretaceous and Tertiary, 65 million years behind, is the most famous of all because in this one they eliminated the dinosaurs. Here yes there seems to be a probable reason: the impact against the Earth of an asteroid of big proportions that provoked Chicxulub's crater, in the Peninsula of Yucatan. A great percentage of the biological kinds disappeared, including the giant reptiles.

This extermination caused the disappearance of approximately 50 % of the biological kinds, between them they are: the dinosaurs, pterosaurios, swimming reptiles, plesiosauros and mosasaurios, ammonoideas, rudistas einocerámidos. The calcareous nannoplancton and the foraminíferos planctónicos experienced important losses though they recovered during the Age Cenozoica.