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341630 2010 年 04 月 07 日 23:55 Reading (loading. ..) Comments (0) Category: Personal Diary
Since the Cambrian Explosion
since the evolution of life on Earth has not been easy, five of which appeared in worldwide mass extinction.
the first time, dating back 440 million years ago in the Late Ordovician, the third largest planet in the history of extinction of species, about 85% of species extinction. Paleontologists believe that this extinction was caused by global climate cooling. About 440 million years ago, and now the Sahara where the land was located in the Antarctic, when the land together near the pole, likely to cause a thick Ordovician ice --- it is this situation. Large glaciers to ocean currents and atmospheric circulation cooling, the temperature of the earth down,
red wing mens boots, locked glacier water, the sea level also reduced the original rich coastal biosphere is destroyed, resulting in 85% of species extinction.
second time, dating back some 36,500 years ago,
red wing work boots, the late Devonian, after the two peaks, with an interval of 100 years, is the fourth largest planet in the history of extinction events, marine organisms have been hit.
third time, about 2.5 billion years ago, the late Permian, the Earth is estimated that 96% of the species extinction, of which 90% of the marine life and 70% of terrestrial vertebrate extinctions , is the largest planet in the history of extinction of species is the most serious incidents. This makes the occupation of the mass extinction nearly 3 million years of marine biology from the main decline and disappear, giving way to new species, ecosystems, also has been one of the most thoroughly updated for the dinosaurs and other reptiles class paved the way for the evolution. Scientists believe that the mass extinction of Earth history, turning from the Paleozoic to Mesozoic milestone. Mass extinction of all other marine species caused by the decline and not 1 / 6, did not make the process of biological evolution to produce such a major turning point.
scientists believe that sea levels have occurred in the Permian dropped and continental drift,
red wing shoes outlet, which caused the most severe mass extinction of species. At that time, all the continents together into a joint of the ancient land, rich and sharp decline in the coastline, the continental shelf is also reduced, the ecosystem has been seriously damaged, many species have become extinct because of loss of living space. More seriously, when the shallow continental shelf exposed, the original organic matter buried in the seabed is oxidized, a process that consumes oxygen, carbon dioxide is also released. The oxygen content in the atmosphere may reduce the life of this animal on land is very negative. As temperatures rise. Sea-level rise, and so many land creatures were drowned, the sea became anoxic zone. Formation in a large number of organic-rich shale deposits is evidence of the disaster.
fourth, dating back 195 million years ago, the late Triassic, an estimated 76% of the species, mainly in the extinction of marine life to disappear. This is particularly evident in a disaster did not sign, only later found to increase sea level falling, there has been lack of investment and a large area of water of oxygen.
fifth time, dating back 65 million years ago, the late Cretaceous period, is the second largest planet in the history of mass extinction, about 75% - 80% of species extinction. In the five mass extinction, this time the most famous mass extinction events, as long as 14,000 years old at this end of the age of dinosaurs known class of ammonites in the sea but also with disappear. The maximum contribution is eliminated in a dominant position on the earth and its ilk dinosaurs, mammals and humans for the final appearance provided an opportunity. This is a disaster from the ground outside the space and volcanic eruption occurred in the late Cretaceous meteorite shower caused by one or more of the global ecosystem collapse. Impact to a lot of gas and dust into the atmosphere, so that sunlight can not penetrate, a sharp decline in global temperatures, this black cloud covered the earth for several years, plants can not get energy from the sun,
red wing shoe store, sea The algae and the gradual death of the forest into the film, the basic link of the food chain was destroyed, a large number of animals die of hunger, which is the dinosaurs.
of mass extinction studies reveal that the planet's ecosystems fragile than we imagine, when it is damaged to a certain extent,
red wing shoes online, it will lead to the collapse of our survival system. If we act because of their own human disaster caused by the arrival of the final moments, we will be survivors of it?
five mass extinction events, are mainly of geological and climate change caused by the disaster. Since the dawn of humanity, and especially after the industrial revolution, human only on the specific biological source of practical value to the development of its indiscriminately, to the neglect of indirect and potential biodiversity value to the maintenance of life on Earth systems have been relentless encroachment of mankind.
Scientists estimate that, without human interference in the past 2 million years, on average about every 100 years, the extinction of 90 species of vertebrates, averaging 27 years have a higher plant extinction. In this context, human disturbance, so that the extinction of birds and mammals 100-1000 times faster. Since 1600, there are records of higher animals and plants extinct 724 kinds. While the vast majority did not know before in the human species has become extinct.
by rough estimates, 400 years, the biological environment of life, shrinking 90% cut in half species, including tropical rain forests are cut down because of the impact of species loss is more prominent. Estimates from the 1990-2020 years due to deforestation of tropical forest species extinction caused by the world's species will decrease 5% -15% reduction of 50-150 species per day. In the past 400 years, the world's 58 species of mammals were extinct, about every 7 years to extinction of a species, the fossil record than the normal rate of 7-70 times higher; 100 years of the twentieth century, the world A total of 23 species of extinct mammals, about one species extinct every 4 years, the fossil record than normal high speed 13-135 times ... ....
The following is a group from the State Environmental Protection Administration, the latest figures: China's rare and endangered species of angiosperms has 1,000 kinds of 28 species of critically endangered species, extinct or possibly extinct 7 species; gymnosperms endangered and threatened 63 species of critically endangered species, 14 species 1 species extinction; threatened 433 kinds of vertebrates, and possible extinction of 10 species extinction ... ....
biological diversity is the most serious threat ever. Survival from extending the scope of human interdependence on Earth all species,
red wing motorcycle boot, many people are thinking the same question - what can we leave the next generation? The world is as rich as possible, or a species increasingly poor of the earth? The rising number of the alarm sounded the end of the century, the human dream of transforming the world cast a shadow, and many people fear to ask themselves: never lonely afterlife of the human, are destined to leave alone? The answer may be an Indian chief from 150 years ago to find the words - \