Cretaceous - Tertiary extinction event artistic depiction of asteroidal impact Overview of the Cretaceous - Tertiary extinction event is Cretaceous to Tertiary time between the mass extinction, which caused the mass extinction on Earth 45% of biological death, making the dinosaurs extinct. Some people think that is caused by a comet, but the largest impact crater on Earth is Barringer Crater, some 13 km in diameter, if there is a such a huge meteorite crater should find a larger fishes, but so far yet to be discovered. But others say that because a large volcanic eruption, resulting in clouds blot out the sun, making many of the plants die, there is a saying that the climate of the mutations, dinosaurs and plant fitness and therefore can not be killed. As of today there are still doubts the hypothesis, so the reason for the extinction of dinosaurs is still a mystery. Because the most likely cause is caused by a comet, but others say that because a large volcanic eruption, resulting in clouds blot out the sun, making many of the plants die, the volcano theory, dating back 6300 years to 6700 a series of massive volcanic eruption thousands of years for some species to disappear from the earth. India's "Deccan rock group" (deccan trap) is the remains of the volcanic eruption, the first of its coverage could reach 58 million square miles (150 square kilometers), equivalent to twice the size of Texas. The main focus of controversy surrounding the extinction is that every time a disaster occurred at a time, and whether the subsequent extinction occurred. Previous studies of the Deccan volcanic eruption will determine the extinction time of the incident from 300,000 to 50 million years. New research shows that the mass extinction of biological Deccan volcanic eruption occurred in one of the largest stage, or after this stage, 80% of Deccan volcanic zone at this stage is spewing out. Another says that the climate of the mutations, dinosaurs and plant fitness and therefore can not be killed. While the most common argument is that a comet caused, but the real reason is still need for more research and evidence. Of 65 million years ago, an asteroid had hit the Earth and crashed in the sea near the Yucatan Peninsula, which led to the dinosaurs on Earth 70%, and species extinction. U.S. scientists say they have a new study found that the asteroid crashed into the ocean depths, far beyond the scientists had expected, the release of water vapor higher than previously estimated amount of 6.5 times. Sean - Old Creek, said the atmosphere in increasing concentrations of sulfate aerosols from two to more lethal impact: First, change the gas, because the upper atmosphere of sulfate aerosols will have a cooling effect; second generation acid rain, because water vapor helps flush with the lower atmosphere of sulfate aerosols. Early studies have shown that these two effects may come from the impact, but relatively low intensity. Increase in the amount of acid rain might help explain why living in the reefs and marine creatures with large surface, like vertebrates, also suffered severely affected. When the acid rain falling into the water, ocean acidity will therefore increase. There is evidence that, on the ph value of the adaptive changes in the marine organisms to survive, while sensitive to changes in ph value can not survive biological. Old Creek, said the production of mass extinction events also may be affected by various environmental factors. For example, when the asteroid crashed into Earth from the sky, the atmosphere will become hot and fierce storms of fire gives off, which makes many large land animals were dried for several hours or several days, burned; and gradual climate change and changes in acidity caused by the ocean will affect the more far-reaching. Initially, Sean - Rick and his colleagues _set_ out to learn the ancient asteroid's orbit that they want from the subsurface structure of the crater found some clues. Old Rick said: "We found that the shallow structure of the crater by the impact is likely to, and not caused by asteroid orbit." If scientists can determine its orbit, that can impact on the environment from the impact, because the absolute most harmful, shock heating is likely to be fast-moving objects along the shock from the impact at the outward direction of projectile out. Currently, Imperial College London researchers are using computer models, the impact at the crater in search for possible clues to determine the surface before impact than by the environmental impact of the asteroid orbit. Yucatan Peninsula in Mexico, the United States, a geophysicist who is leading the crash clues extinction of the dinosaurs. In the Yucatan Peninsula have a staggering impact crater diameter of about 180 km. It is known as the "奇科苏卢布" crater, buried it in a few hundred meters of the sedimentary rocks below. Related clues hidden in this big hole, because some parts of the world the unique rock formations, even if only a millimeter to several centimeters thick, may help researchers decipher the mystery of dinosaur extinction. But researchers now know, there is a 10 to 15 kilometers in diameter objects fall in the Gulf of Mexico at an alarming rate. In the past 25 years, most scientists believe, although there is still some debate on specific issues, but the meteorite collision with Earth is closely related to the extinction of these species. However, researchers were able to declare "奇科苏卢布" meteorite is the culprit, they need to find out "奇科苏卢布" meteorite crashed into Earth exactly how. To uncover the mystery, geophysicists at the Yucatan peninsula, the U.S. underground drilling to 1,500 meters, and hope that more understanding of this huge object in the case of colliding with Earth and accurately explain the turn of the Cretaceous-Tertiary ╠ era, this big mass extinction in terms of collision in the end what role to play. U.S. researchers say, the "奇科苏卢布" meteorite is caused by the worldwide mass extinctions of the clues are still hidden in the rocks and sediments in the crater. However, to determine the 奇科苏卢布 "murderer" during the attack is much more difficult, especially from the Cretaceous - Tertiary alternative era, the core has been there through a long 30 years, so , the recent "奇科苏卢布" drilling crater appeared to find the answer almost as many new problems.
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Introduction
Cretaceous - Tertiary extinction event in Earth's history is a major extinction event, occurred in the Mesozoic between the Cretaceous and Cenozoic Tertiary, about 65.5 million years ago wiped out most of the animals on the planet at that time and plants (including dinosaurs). Cretaceous - Tertiary extinction event since the demise of the dinosaurs and the rise of mammals is known, however, be pointed out: Permian - Triassic extinction event wiped out about 90% of the Earth at the biological, geological age of the most serious biological mass extinction event. KT boundary outcrops in Cretaceous and Tertiary strata, between a layer of iridium-rich clay layer, called the KT boundary. K is in German, Cretaceous (Kreidezeit) acronym, T is the Tertiary (Tertiary) of the acronym. International Commission on Stratigraphy no longer recognized as the third century is the official name of geological time, from the Paleogene and Neogene replaced. Therefore, the Cretaceous - Tertiary extinction event can be called the Cretaceous - Paleogene extinction event (Cretaceous-Paleogene extinction event). Dinosaurs (excluding birds) of the fossils found in the KT boundary only the lower, indicating their extinction event occurs in this (or before) the rapid extinction. A small part of the dinosaur fossils found in the KT boundary above, but these fossils are considered because of erosion and so on, and taken away from the original location, and then deposited in younger sediments. In addition to other dinosaurs, Cang Long Branch, Head plesiosaur, pterosaurs head, and a variety of plants and invertebrates, but also extinction of the incident. Mammals and birds are to survive, and evolution of radiation, a new generation of dominant animals. Most of the scientists speculate that the extinction is caused by one or more reasons, for example: caused by an asteroid or comet impact event, or a long period of volcanic eruptions. Chicxulub crater and the crater such as the Deccan shield volcano eruptions, and the KT boundary time to close, was considered most likely the main cause of the extinction event. Events or volcanic eruptions will impact a lot of dust into the atmosphere, and cover the provision of the sunlight, reducing photosynthesis, and thus on the global ecosystem around the impact. But a few scientists believe that this is a slow extinction event occurred, and the extinction of a gradual change in sea level and climate.
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Duration
On the Cretaceous - Tertiary extinction event the duration of the dispute is still in a long time, because some of the theory that the extinction of the process is very short (from several to thousands of years between), while other theories hold that extinction process lasted a long time. Since it is impossible to find a complete fossil record of species, extinct species, so the real time to extinction may be later than the end of the fossil record. Therefore, extinction is difficult to determine the experience of time. Scientists have found a few across the KT boundary strata with fossils, dating from before the millions before the KT boundary, to the KT boundary of the nearly 2 million years.
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Ecological disaster
The strength of previous extinction Cretaceous - Tertiary extinction event caused a large extinction (see left, the Cretaceous - Tertiary extinction event at the K and the extinction of intensity between Pg) Coccolith (Coccolithophore) and molluscs (including Ju Danya Gang, thick shell clams, aquatic snails, mussels), and to the hard-shell animals living animals perished in the extinction event, or suffer a severe blow. For example, mosasaurs ammonites are considered to feed on these marine reptiles in the Cretaceous - Tertiary extinction event in the demise. Omnivorous, insectivorous, and scavengers to survive in this extinction event, possibly because their diet more varied. End of the Cretaceous did not seem completely herbivorous or carnivorous mammals. Mammals and birds by the insects, earthworms, snails ... and other animals for food, survival in the KT event, and these dead plants and animals Zeyi animals. Scientists assume that these organisms to organisms living on organic debris, was able to collapse in the extinction of flora survive. Biological communities in the river, only a small number of animals destroyed; because many biological communities to the river washed down from land-living organic detritus, and less directly to the living plants for a living. Ocean had a similar situation, but more complicated. Animals live in the pelagic zone, than the impact on the survival of animals in the sea bed is also large. With the animals living in pelagic phytoplankton living almost to live, and live in the sea-bed animals, places bio-organic detritus, or can be converted to bio-organic detritus. Survived the extinction event in the species, the largest land animal is the crocodile and from Lombok, is a semi-aquatic animals, and can bioclastic living. Scavengers of modern crocodiles can be a living, and for several months without eating; young crocodile is small in size, slow growth, mostly in the first years of invertebrates, dead creatures for food. These characteristics may be the crocodile to survive through the critical end of the Cretaceous extinction event. After the extinction, resulting in many vacant niche, ecosystem restoration took a long time before the original diversity. Microorganisms After the first since the Ordovician, radiolarians (Radiolaria) once disappeared from the fossil record. In the Cretaceous / Tertiary border, you can find a small amount of radiolarian fossils. There is no evidence at that time was a large-scale extinction of radiolarians. In the early Paleocene radiolarian very busy in the Antarctic area, which may be due to the cold climate. Nearly 46% of the diatom species, to survive to the ancient New World. This shows the degree end of the Cretaceous extinction of diatoms is not serious and the degree level to the species level only. Since the 1930s, scientists have started studying the handover of the Cretaceous and Tertiary foraminifera door (Foraminifera) extinctions. Since the end of the Cretaceous impact event may result in the theory of the extinction event occurred, the more scientists study the foraminifera door when KT boundary extinction conditions. But the scientific community is divided into two views. Some people think that the main door ① foraminiferal extinction events because of this video. ② Other people feel that the transfer of the Cretaceous and Tertiary periods, there have been many foraminifera extinction of the door and recovery. Benthic foraminifera mainly organic detritus, with the end of the Cretaceous extinction event caused by a large number of marine organisms died, many of the benthic foraminifera also with those who perish. Recovery in the marine ecosystem, the benthic foraminifera increased food sources, species formation but also with those increases. Phytoplankton in the early Paleocene recovery, providing large-scale low-dwelling foraminifera food. Until hundreds of years after the extinction event, about the early Paleocene, low habitat ecosystem for them to fully recover. Marine invertebrates Fossil evidence shows that in the Cretaceous - Tertiary extinction event before and after, marine invertebrates have changed considerably. However, the lack of fossil record, making it impossible to show the proportion of true extinctions. Ostracoda Programme (Ostracoda) is a key link crustacean subphylum, these small animals in the upper Maastrichtian very busy, leave a fossil record in many areas. A key link for the fossils of ostracods, Ostracoda Gang shown in the diversity of the Paleocene period, other than the Tertiary period. However, the current study can not determine the ostracod Gang recession, is the end of the Cretaceous occurred before or after the event. The key link in the Late Cretaceous coral coral heads, nearly 60% are gone, there is no survival to the Paleocene. Usages studies have shown that habitat in warm, subtropical, shallow areas of coral species recorded, 98% die. Those who inhabit the colder, with less light, growth alone can not form a coral reef, less affected by extinction. Photosynthesis of algae and coral symbiosis, in the Cretaceous - Tertiary extinction event of a large number of extinction. But in addition to research into the KT boundary strata of the Paleocene fossil coral outside, but also to refer to changes in coral reef ecosystems at the time. After the KT boundary, cephalopods, echinoderms, the number of double-hull is the key link, showing significantly reduced. Most of the brachiopods, the late Cretaceous extinction event in the survival and diversification since the early Paleocene. In echinoderms, nearly 35% are lost in this extinction event. Among them, live in low latitudes, the highest proportion of shallow-water echinoderms perish; and live in the mid-latitude, deep-sea regions of echinoderms, the extent of the affected is small. This may be the cause of the extinction model habitat loss, especially in shallow-water carbonate platform in the region. Other invertebrates, such as thick shell clams (which can form a reef clams) and the imbricate clams (close relatives of modern large scallops), in the Cretaceous - Tertiary extinction event of all perish. Fish KT boundary in the upper and lower strata, a large number of fossil fish have jaws, for scientists studying the extinction patterns of marine invertebrates. Pisces in the cartilage, there are nearly 80% of the sharks, rays present, rays of the subjects survived the extinction event; in Teleostei, only less than 10% of the families disappear. Seymour Island, near Antarctica, the fossil record shows that the upper KT boundary a large number of bony fish died. Scientists have inferred the fish was facing an environmental change, and KT event should be the main cause of environmental change. However, marine and freshwater environments, reducing the fish suffered the impact of environmental changes. Terrestrial invertebrates 14 locations in North America, flowering plant fossil was used to study changes in insect diversity and extinction ratio. The researchers found that in the Cretaceous before the KT boundary, there are plenty of plants, insects, very diverse. In the early Paleocene (about 170 million years after the extinction event), is still very diverse group of plants, from insects feeding is less. Terrestrial plant In the Cretaceous - Tertiary extinction event occurs, not widely distributed in plants around the world for research. However, individual areas for the flora of the discontinuity. In North America, the Cretaceous - Tertiary extinction event occurs when a large number of plants destroyed, but at the time of extinction before the incident, has been a marked change in plant communities. High latitudes in the southern hemisphere, such as New Zealand and Antarctica, flora, and no substantial species disappeared, but in the prosperous situation of the plant is short-term, dramatic changes. In North America, nearly 57% of plant species extinction. In the Paleocene, the fern leaf fossil record shows that ferns began to once again prosper and flora began to recover. Mount St. Helens in 1980 after the outbreak of revival is also a similar situation of ferns. Since the late Cretaceous extinction event, the integrity of the damage caused Flora, then a large number of saprophytic proliferation of biological, such as fungi, these organisms do not need to rely on photosynthesis, and decomposition of dead plant to absorb nutrients. Fungi flourish only lasted a few years, when the atmosphere is back to normal, photosynthesis of plants (eg ferns) began re-growth. Amphibians There is evidence that amphibians do not because the Cretaceous - Tertiary extinction event and a lot of destruction, most members survive. Montana for a number of salamander fossils that is a salamander seven in six genera survived the extinction event. The frog seems to survive to the Paleocene epoch, only a few species extinction. However, in the fossil record, the number of frogs in the families and genera are not clear. A case for the three Montana frog research indicates that they are not subject to the late Cretaceous extinction events. These data showed no amphibian families perished in the extinction event, or be hit. Because the survival of amphibians in the water, or in the sediment, soil, trees and building points, or survival of the hole in the rocks. Non-archosaurs reptiles In the Cretaceous - Tertiary extinction event, the non-archosaurs reptiles are turtles head, super long scale projects (including today's snakes, lizards, earthworms Lizard) survived, in addition to raw water from semi-Lombok (part of the original master classes under the dragon, disappeared from Miocene) also had survived the extinction event. More than 80% of the Cretaceous turtle, survived the incident. In the late Cretaceous period, a total of six turtle families, have survived to the third century, and survived to the present. The existing scales of the existing beak head dragon lizard include: beak head Lizard Head, Squamata. Early in the Mesozoic, the beak head Lizard Head is very successful group of animals, and widely distributed, but began to decline in the mid-Cretaceous. Beak head Lizard Head is now the only remaining one, the only remaining in New Zealand. Existing Squamata include: lizards, snakes, lizards, and earthworms, they occupy a lot of different Jurassic niche and successfully survived the Cretaceous period. Squamata survived the end Cretaceous extinction event, as today's most successful and diverse reptiles, the current total of more than 6,000 species. There are currently unknown scales any purpose He Lusheng Branch, disappeared in the extinction, the fossil evidence shows their numbers did not change significantly. These terrestrial animals Squamata small size, adaptable metabolic rate, and the ability to change the habitat, is that they are late Cretaceous / Early Paleocene survived reasons. Non-archosaurs marine reptiles, including mosasaurs, plesiosaurs, which are the advantages of Cretaceous marine predators, but in the end of the Cretaceous extinction. Archosaurs Archosaurs consists of two main clades, mosaic classes archosaurs include crocodiles ankle with relatives, the birds long neck contains the main class of pterosaur head, dinosaurs, and birds. Exingchaomu Wyvern Head In the Maastrichtian, the only category to determine the existence of pterosaurs pterosaurs Dragon, Dragon pterosaurs are extinct extinction event. In the mid-Cretaceous, there are 10 families and survivors of large pterosaurs, and then gradually decline. Smaller pterosaurs is early Maastrichtian been destroyed before. Pre-order in Maastricht, there have been small animals, recession, and the phenomenon of large animals more prosperous. During this period, new birds began to diversify subclass and replace the other birds and pterosaurs original niche, these animals may be direct competition, or just take a new subclass of these birds disappeared species niche space . Most of the dinosaurs Many studies end of the Cretaceous extinction, are concerned about how the extinction of the dinosaurs. Apart from a few of the controversial research, most scientists agree that dinosaurs (excluding birds) extinct in the late Cretaceous extinction event. On the extinction of the dinosaurs was divided into two schools of ① The first school that last millions of years in the Cretaceous, the diversity of dinosaurs have a recession; ② The second school believes that, in the last millions of years, and no indication of the decline of the dinosaurs. At present, scientists still can not under the dinosaur fossils of this period, in which two schools to make a conclusion. There is no evidence that the late Maastrichtian dinosaur, a cave, swimming, diving and other habits, it is not possible to reduce the impact of environmental changes. Some small dinosaurs may have survived, but they are, regardless of herbivorous or carnivorous, will face a shortage of plants or prey. In recent years, the temperature on the dinosaur is increasing evidence of animals, dinosaurs, crocodiles and close relatives of different metabolic levels, helps scientists study their extinction in the late Cretaceous and survival reasons. Crocodiles are cold-blooded animals, can not eat for several months; and close to the warm-blooded dinosaur body needs more food sources to maintain a faster metabolic rate. So when the KT event, the collapse of the entire food chain, need a lot of food dinosaur extinction, while the crocodiles alive. Such as birds and mammals, animals in temperature, probably because smaller and required less food, coupled with other factors, to survive in this extinction event. Birds Mammal Cretaceous mammals of all the major clans, including: oviparous monotremes, multi-target tumor animal teeth, there are bags under the Programme, under the real animal classes, spine toothed beast superfamily (Dryolestoidea, the original beast subclass), and Gondwana beast suborder (Gondwanatheria, subclass belonging to animals), have survived the Cretaceous - Tertiary extinction event, but they suffered heavy losses. Living in North America and Asia of the original triangular tooth marsupials animal superfamily (Deltatheroida) was extinct. Hell Creek group in North America, more than 10 kinds of animals present in the tumor teeth at least half of the members, and 11 species of marsupials, have been destroyed. In the Cretaceous - Tertiary extinction event 3000 years ago, mammals began to diversify. Cretaceous - Tertiary extinction event prevented the further diversification of mammals. The present study indicates, despite the disappearance of the dinosaurs left a large number of niche, but not so explosive diversification of mammals. One study noted that a number of mammalian orders, in the Cretaceous - Tertiary extinction event began shortly after the diversified, including Chiroptera (bats), whale Artiodactyla (whales and dolphins, and cloven-hoofed); but another studies have proposed different views, that in the Cretaceous - Tertiary extinction event, only began to diversify marsupials. Before the KT event, the mammalian body is usually small, close to the mouse's body, making them easy to find refuge. In addition, some early monotremes, marsupials, and so is semi-aquatic mammals, or burrowing animals, like many modern mammal habitat. Semi-aquatic, or burrowing mammals in the Cretaceous - Tertiary extinction event caused by the environmental pressure to find shelter.
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Fossil evidence
North American fossil In North America, continental stratigraphic sequence in the late Maastrichtian and the KT boundary abundant pollen types after the fern leaves, most highlight the differences between the two different periods of formation. In the KT boundary occurred before the oldest known dinosaur fossil-rich strata in western North America, especially Montana Hell Creek Group (Age to the late Maastrichtian). If the group with the Hell Creek, Montana, Alberta, Canada and the Judith River Group / Dinosaur Park Formation (early years, about 75 million years ago) compared to the last 1000 years can be drawn from the Cretaceous change in the number of dinosaurs. Limited geographical distribution of these strata, only found in parts of North America. In the mid-to late Campanian strata in the diversity of dinosaurs than any other period. Late Maastrichtian appears several large Dinosaurs: Tyrannosaurus, Ankylosaurus, Pachycephalosaurus, Triceratops, and the dragon horn, before the events appear in the extinction, the region's food abundant. In addition to a wealth of dinosaur fossils, the fossil record of plant species can be reconstructed from the sharp decline as evidence of extinction. Strata above the KT boundary, pollen confirmed that the period of the advantages of fossil plants are angiosperms; at the junction formation, very little pollen fossils, mainly fern leaf fossils. KT to the upper boundary from the exploration, we can see that the number of fossil pollen gradually increased. The area after the eruption, but also the plant fossils found in the change mode. Marine fossils Paris Museum of Natural History collection of mosasaurs plankton of Dan Haisheng large-scale, rapid demise occurred at KT boundary time. Early before the KT boundary, Ju Dan Yagang have small, slow decline may be related to the Late Cretaceous regression on the remaining time is in the KT boundary extinction. Bivalvia imbricate most species of clams Division, before the KT boundary has been gradually destroyed; Also in the late Cretaceous, ammonite diversity also appeared small, gradual decline. Studies have shown that the ocean in the Late Cretaceous, there have been several different models of extinction occurred some time staggered, the end of the Cretaceous extinction patterns at the end of extinction.
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Geological evidence
Deccan Shield See entry "of the Deccan shield" Deccan shield before 2000, there is the Deccan flood basalt shield is the main cause of this extinction event, but since the eruption began 6,800 million years ago, and continued more than 200 years, so at that time that the Deccan Shield volcano caused by the extinction event should be gradual and slow. But now there is evidence that 2 / 3 of the Deccan shield terrain, is formed in a million years, occurred at 6,550 million years ago. Shows that the eruption caused a rapid extinction Deccan shield volcanoes caused by a number of ways by the events of extinction, dust and sulfur dioxide and carbon dioxide and other greenhouse gases a large number of spray, dust down to the surface the amount of sunlight, plants reduced photosynthesis; When the dust slowly to the surface when landing, volcanic eruption of carbon dioxide gas, may increase the greenhouse effect. The death of many plants, herbivorous dinosaurs perished because there is no food, but have also become extinct carnivorous dinosaurs. . Before the mass extinction of the dinosaurs, volcanic eruptions of gas, it seems related to global warming. There is evidence that the Chicxulub impact event 50 million years ago, the atmospheric temperature has increased by 8 ° C. In the Deccan shield volcano is still considered slow extinction event, Luis Alvarez had already made a few paleontologists are confused by the information. He warned that time was not accepted, but later research work for the fossil layer, the early studies proved that wrong. Currently, most paleontologists have generally accepted the late Cretaceous impact event is the main reason for the extinction event. However, the son of Luis Alvarez Walter Alvarez of China (Walter Alvarez) that before in this impact event on Earth other significant events have occurred, such as: sea level fall, resulting in the Deccan Shield large-scale volcanic eruption, they may also cause the extinction of a combined one. Multiple impact event Chicxulub crater has been found in the current number of craters, they form the equivalent of KT boundary time. These findings point out that there may be times when the impact occurred; this pattern occurred in 1994, similar to Shoemaker - Levy 9 comet, because of tidal forces and the separatist, a number of pieces in the next few days after another hit Jupiter . These craters include: Ukraine, Bo Taishi crater, 24 kilometers in diameter, formed for about 65,170,000 years ago (the error is 64 million years), the North Sea in the silver pit crater, 20 kilometers in diameter, the formation time of about dating back 6,500 million years ago to 6,000 million years ago. Off the coast of the Shiva crater in India, was located in the Tethys Ocean, multiple impact event is one of the possible crater. Maastrichtian of regressive events There is clear evidence shows that in the Cretaceous large-scale Maastrichtian regression, reaching the lowest level since the Mesozoic. In some parts of the world Maastrichtian strata, the earliest part of the sea bed, the earlier part of the coast of formation, is the latest part of the terrestrial strata. The formation is not due to orogeny and lean, signs of bending, so the most likely explanation is regression. There is no evidence of regression reason, the more common explanation is that the activities of the lower ridge, and these huge underwater mountains were its own weight with the slow _set_tlement of the seabed strata. Caused a substantial regression of mass disappearance of the continental shelf, perched on the continental shelf (or shelf, the continental shelf) the most abundant marine life, the regression may result in the extinction of marine life. Studies also show that sea level change, not enough to cause such serious ammonite extinction. May cause a decline in sea level atmospheric circulation system and the current system changes, the formation of climate change; narrow area of the oceans would also decrease the albedo of the surface, leaving the global warming. Large-scale regression has made so many mainland's disappearance, such as the North American Western Interior Seaway. The disappearance of these waters, destruction of many found in 1000 million years ago, biological prosperous coastal plain, such as Dinosaur Park group. Meanwhile, the relative increase in the land, rivers, the length of the longer survival of the freshwater area expansion. Marine and Freshwater Studies on changes in the region, increasing the freshwater invertebrates, and reduce the number of marine organisms is, for example, sharks.
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Theoretical Hypothesis
Cause of the extinction Although the Cretaceous - Tertiary extinction event caused the extinction of many species, but different clade, clade, or within each, showing a significant difference in the degree of extinction. Cover the provision of particles in the atmosphere of the sun, reducing solar arrived at the surface, dependent on the biological photosynthesis decline or extinction. In the Late Cretaceous, the bottom of the food chain is dependent on the biological composition of photosynthesis, such as phytoplankton and terrestrial plants, as the current situation. Evidence that herbivores decline due to plant depends on, and reduce the number; Similarly, the top predators (such as Tyrannosaurus) are successively affected. Asteroid impact hypothesis (impact events) Impact event can cause a lot of dust into the atmosphere, cover the provision of sunlight, for up to 1 year or 1 year period. In addition, a large number of sulfuric acid in the form of aerosols into the stratosphere, so that the amount of sunlight reach the surface reduced by 10% to 20%, prevent plant photosynthesis; stratospheric aerosol layer, the deposition may be required within 10 years time, which will lead to plants, a large number of phytoplankton disappear, and in the food chain of the herbivorous animals, predators also with those who perish. And organic detritus to small creatures, less affected by extinction. Within a few hours after the impact event, there will be a large number of infrared penetrate the atmosphere, exposure outside of the biological damage. Impact ejecta and fall again, will cause a global fire storm. Late Cretaceous atmospheric oxygen content, will contribute to the fire around; and Early Tertiary atmospheric oxygen content, showing signs of declining. Had the fire occurred a global storm of carbon dioxide in the atmosphere will rise, and the dust in the air, fallout, to continue to cause short-term greenhouse effect. Survival in the event of biological impact, perhaps because of these effects and death. II. Volcanic eruption hypothesis Because of the eruption, a large number of emitted carbon dioxide, the greenhouse effect that causes global acute shock, making the plants die. Moreover, the volcanic eruption makes a lot of salt, the release element, the ozone layer break, harmful ultraviolet radiation the Earth's surface, resulting in biological extinction. Italian physicist Antonio - brushed off recent, mass extinction of the dinosaurs probably because large-scale submarine volcanic eruptions. Professor brushed off the late Cretaceous, the Earth beneath the ocean a series of massive volcanic eruptions, thus, affecting the thermal balance of water, thus causing the land to climate change, thus affecting the need for large quantities of food for a living the survival of dinosaurs and other animals. His argument is that the modern submarine volcanic eruptions on the impact of ocean and atmosphere are well known, but its impact than the 65 million years ago the extent of submarine volcanic eruptions is much smaller.