history the biggest extinction reasons found
recently, the Chinese and foreign ancient research team for the 252 million – year – old creature at the end of the Permian mass extinction event was studied, the cause of the original, & other; High temperature & throughout; Extinction is deadly killer! The results were published in the authoritative journal science, and was widely reported by the media. The high temperature is how? At the end of the Permian extinction 5 million years after the creature out is a kind of what kind of scene? The mass extinction what enlightenment to us? Today, we had an interview with one of the researchers & ndash; & ndash; Professor of China university of geosciences xu-long lai, asked him to give us a detailed interpretation.
252 million years ago, the earth high temperature lead to biological extinction
the liaoning daily: as common sense, we already know that earth has experienced five mass extinctions why said about 252 million years ago, at the end of the Permian extinction event is one of the biggest?
xu-long lai: life on earth has experienced five big biological extinction, the first time in 440 million years ago in the late ordovician; The second time in a 375 million – year – old late devonian to early; For the third time in the 252 million – year – end Permian; For the fourth time in 208 million years ago the late Triassic; The fifth time in the end of the cretaceous period, 65 million. Occurred in the global biological big at the end of the Permian extinction, about 90% of Marine species and 70% of invertebrate animals disappear in the incident, a large number of extinction, active in the Paleozoic & other; Throughout the &; Level of extinction by almost 96%. Other all caused by the Marine species extinction of decline is not and 1/6, may say, the degree is the most widespread extinction.
the liaoning daily: one is a part of the biosphere, is doomed to extinction such big events as we are concerned. And at the end of the Permian extinction is the biggest, will certainly be also caused the scientific community a great deal of research interest, your team studied the cause of the extinction event this time, so what is the direct cause of the extinction?
xu-long lai: our root university and the university of Leeds in England, Germany, Ireland – nuremberg university in cooperation study found that lead to the extinction and after early Triassic equatorial low latitude area ecosystem is the main reason of the collapsed 5 million years when the temperature is too high.
the liaoning daily: high temperature is how to draw?
xu-long lai: in short, through the calculation of conodont oxygen isotope ratios, for the first time to get the most detailed and accurate of the late Permian to early Triassic Marine temperature curve, learned from the curve near the equator ocean surface temperatures of up to 40 ℃, far higher than modern equatorial sea surface temperature, high temperature event happened, close to the sea creatures and stop the lethal temperature of photosynthesis.
the liaoning daily: why determination of conodont?
xu-long lai: conodont is geological history of an ancient fish like eels teeth, general size is 0.1 mm or so. Conodont fossils is not only the standard of dividing Marine strata geological s, conodont composed of calcium phosphate bone is also very good to record the oxygen isotopic composition of ancient seawater. And the oxygen isotopes in biological skeleton is formed by the environmental temperature control, through the oxygen isotope ratio in the specimens of conodont research can restore the paleotemperature of hundreds of millions of years ago.
the liaoning daily: how to determine which fossil or which areas, formation are the Permian?
xu-long lai: due to the complexity of the earth has experienced many times of transformation and change of the earth’s geological age need to explore its own material records from earth. Geological era of time has relative time (age) and absolute time. Geologists according to rock sedimentary sequence, the phases of biological evolution and relationship between geological body established a relatively s geological history, we say at ordinary times the Cambrian, Permian, Jurassic and cretaceous are relative geological time. Is the Cambrian trilobites era, for example, in the Permian – Triassic period, conodont Marine stratigraphic division is the best time of fossil evidence. Plasmids can base areas, on the other hand, some of the degree of the decay of radioactive elements such as uranium that isotope age to determine the geological & other; Absolute & throughout; Age (time), such as the absolute age of the Permian and Triassic boundary by measuring, probably around 252 million years ago. When we are doing the research, is usually a relative age with the combination of absolute age namely lithofacies, fossil and isotopic jointly determine the long time. Determines the formation time, we can be presented to it & other Throughout the ancient information &; Systematic research.
biodiversity is extremely low status continue 5 million years
the liaoning daily: in 252 million, before the extinction of is what? What are the creatures?
xu-long lai: before the end of the Permian extinction on the earth is filled with a variety of plants and animals, including the original reptiles and amphibians, including trilobites, brachiopods, corals and sea lilies, all kinds of Marine life.
the liaoning daily: how long the extinction process lasted for a while? How to conclude that destroyed? After the extinction of the earth is what?
xu-long lai: under the Permian – Triassic boundary dozens hundred centimeters to widespread line a mass extinctions, it has been widely discovery. Destroy this dynamic process lasted for 200000 years, this time in earth’s geological history is only flashed by. Biological extinction after showing a large & other; Dead zones & throughout; : in the equatorial low latitudes very damp but almost no biological growth. Survive and only a few categories, Paleozoic tall plants only short type. No forests and animals on land, only some shrubs and ferns. The ocean not fish and Marine reptiles, only some shellfish biology.
the liaoning daily: you just said the extinction that earth’s biosphere in 5 million didn’t resume & other Strength & throughout; ?
xu-long lai: at the end of the Permian extinction after early early Triassic, the biodiversity is extremely low dead zones in lasted for 5 million years.
the liaoning daily: high temperature caused by too?
xu-long lai: yes, because of early Triassic equatorial low latitude area is also very hot temperature. Biological high metabolic rate is difficult to adapt to the high temperature, only in the higher latitudes gives animal refuge from hot temperature.
in the ocean, the Paleozoic the dominant brachiopods suffer has never recovered, this is mainly because the greenhouse effect produced by the high temperature caused by the water dissolved oxygen to reduce for Marine animal was tortured by heat added to the gloom. Only some of the more easy to regulate metabolism and adapt to the environment of high temperature mollusks in a short period of time to get a good recovery.
in the history of modern earth extinction rate exceeds the fossil record levels
the liaoning daily: for the cause of the biological extinction has always been on the international research hot topic, and now the direct cause of extinction, we found that high temperature, then the causes of the high temperature?
xu-long lai: through the study found that when a massive volcanic eruption is the release of greenhouse gases and related mechanism caused by the greenhouse effect caused by high temperature of the main causes of deadly. The current international academic circles is generally believed that the Siberian basaltic volcanic eruption of very large scale is the most important events in such events. In addition, in south China in guizhou, guangxi, guangdong, hunan and other places of many profile (at that time the equatorial low latitudes) of Permian Triassic boundary especially extinction line appeared a lot of acidic volcanic tuff, it shows that when there is also widespread in the acidic volcanic activity, and natural to us the equatorial low latitudes in the research of high temperature has a relationship. When such frequent volcanic activity is closely related to the interior of the earth’s movement at that time. In short, these volcanic eruption and land fire events such as high temperature closely related to Marine extinctions and ocean anoxic, occur almost at the same time.
the liaoning daily: violent volcanic eruptions will produce what kind of consequences?
xu-long lai: volcanic eruption and the excess carbon dioxide in the atmosphere, create a “greenhouse effect”, and many plants photosynthesis will be weakened dramatically in 30 ℃ above, the role of fungi as disintegrator is greatly enhanced with the increase of temperature, these factors lead to the terrestrial carbon can’t buried coal, so as to make the elevated atmospheric co2 levels linear cause temperature continues to rise again. High temperature can cause the equatorial low latitude area productivity greatly reduced, and the sea is will tend to eutrophication for the strengthening of terrigenous weathering. In addition to the volcanic eruption, at present about the extinction of other reasons are also studied and discussed, such as an asteroid impact and cosmic radiation, plate tectonics, large-scale regression, transgressive, scientists trying to find more evidence, in order to fully reveal the causes of the mass extinction of life.
the liaoning daily: back to the present. The United Nations published in 2006, “the global biodiversity outlook,” said human is currently director sixth earth extinction event, which is one of the biggest since the dinosaurs. So, the dominated by high temperature at the end of the Permian biological extinction gave us what kind of enlightenment?
xu-long lai: Chinese and foreign scientists have statistical current extinction rate, the results show that the extinction of life on earth now rate is accelerating, some scientific research shows that modern life on earth extinction rate than in the geological history of the fossil record shows extinction rate is high, the human need to take effective protective measures. Although biological mass extinction at the end of the Permian is a massive volcanic eruption caused by intense geological activity such as high temperature, but is enough to give us a great deal of warning. One of the most important is the deterioration of ecological environment, especially the greenhouse effect caused by high temperature and atmospheric environment of dramatic change, because our earth is being disturbed by the greenhouse effect, climate change is very severe, and now the greenhouse effect more related to human activities. No matter how smart, how advanced the science and technology, human beings will always be a part of the biosphere, life on earth has always been a part of the world this net, so to protect this and other Net & throughout; , avoid the earth ecological environment of dramatic change, and it should be said that our common responsibility.//our reporter wang lina/guitar
Dr Xu-long lai. China university of geosciences (wuhan), vice President, paleontology and stratigraphy professor, doctoral supervisor, the state council special allowance from the government. Nearly 20 for many years engaged in biostratigraphy, ecological stratigraphy, sedimentology, and paleogeography, the molecular paleontology of the teaching and scientific research work, as a project and the main participants to preside over or participate in the national natural science fund project, department and international cooperation projects, more than 20 research projects, publications at home and abroad nearly hundred academic theses, as the main author published five monographs.