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Mosquito bites led to the extinction of dinosaurs?

Viewed 668 times 2018-7-11 22:46 |System category:Others

In the Mesozoic era, 70 million to 200 million years ago, our earth was dominated by reptiles such as dinosaurs. These reptiles were flying in the sky, climbing in the ground and swimming in the water. They ruled the earth for more than 100 million years. However, in a relatively brief period about 65 million years ago, they suddenly became extinct on earth. So what caused such a once-mighty species to suddenly disappear? Although many scientists have devoted their lives to the hunt for this unprecedented killer, many suspects have been caught today, but the real culprit remains elusive.

According to incomplete statistics, scientists have provided more than 100 suspects and clues to kill dinosaurs, the most famous and most popular of which is the asteroid impact theory. In this view, in about 65 million years ago, an asteroid hit the earth, the impact caused a lot of dust, canopy, low temperature, plants wither, finally caused dinosaurs to not survive and died out.Firstthe time it took for an asteroid impact to wipe out the dinosaurs should have been brief, while the fossil record shows that the dinosaurs went extinct for millions of years. Second, if an asteroid impact caused the dinosaurs, so, turtles, crocodiles and lizards these contemporary with dinosaurs and is closely related with dinosaurs reptiles why can survive and have been living now? Third, an asteroid impact would cause the earth to go into low temperatures without sunlight all year round, but scientists have discovered the cretaceous bee amber, which tells us that earth was not very cold at the time. Other explanations, such as plant poisoning, volcanic eruptions, climate change, cosmic radiation annihilation, competitive pressures, and so on, have similar inconsistencies.

In geological history, there have been many large-scale paleontological extinctions [8,9]. Studies have found that the extinction of organisms has a certain mechanism [10], and most of the extinction events occur at the peak of the extinction period [11]. That is, when the morphological characters of a species are highly differentiated and reach a peak, they tend to be extinct soon. The less differentiated relatives often survive (Fenton,1935) .the extinction of trilobites, ammonites and dinosaurs is no exception. As we know, "highly differentiated morphological traits" are manifestations of evolution and adaptation, and this "extinction law" of paleontology seems to contradict Darwin's "survival of the fittest" theory. As a result, some argue that the extinction of paleontology has nothing to do with "competition for survival," but rather with the devastation caused by an extraterrestrial impact. In fact, an impact is an accidental event, and it can not explain the regularity of things that "most extinctions happen in the heyday of extinct organisms". Since the extinction after the "peak", then the extinction must be related to the "peak". Asteroids are not "alien imperialist" bombs. When they see life on earth flourish, they throw one at earth. The reason for the extinction, therefore, lies in the biology itself. Fast reproduction, the number, reach a "golden", (1) it may destroy the living environment, cause its own extinction, (2) nourish the natural enemies, kill themselves, (3) cause the epidemic, and finally be infected with the disease and perish. The extinction of the dinosaurs is also among the three reasons.

In the age of dinosaurs, dinosaurs had few predators and no evidence of serious environmental damage. So, most likely, a plague epidemic led to the extinction of dinosaurs. So why do mosquitoes and other stinging insects kill dinosaurs? This can be examined from three aspects:

First, from the growth history of insects, including mosquitoes, the Mesozoic is dinosaur era, is an age of insects, mosquitoes and horsefly sucking insects is produced in that time, and flourished at the end of the cretaceous period. At the time, warm temperatures, seasons and swampy swamps provided ideal breeding grounds for mosquitoes. The sky was filled with these little blood-sucking insects. Initial mosquito beak short, not suitable for sucking, but towards the end of the cretaceous and paleogene, some species of mosquitoes, such as claw mosquitoes found in Germany and China liaoning fushun, found the jehol midge mosquitoes (amber) evolved a long beak, very suitable for sucking, they can sap-sucking animal's blood. In fact, at the time midges appeared, many of today's bloodsuckers were also born. Now that mosquitoes and other blood-sucking insects have appeared, They need a blood sucking object, and dinosaurs were the largest species at that time, so dinosaurs became a good meal for blood-sucking insects like mosquitoes.

Second, from the point of comparative biology, tortoise, lizards and other animals and dinosaurs are of reptiles of the immune system is not perfect, no complete lymphatic duct inside its body, and no lymph nodes, and the immune organ thymus this only bad development, generally no clear differentiation of cortical and medullary. Due to the lack of diversity of antibodies in the body fluids of reptiles, they are not competent to deal with the specific immune work of various pathogenic organisms. When the body is attacked by germs, immune cells are added to the blood, which is characterized by fever. Reptiles are cold-blooded, the immune cells proliferation speed is very limited, so when confronted with the germ of mosquitoes and other insects, the epidemic infectious disease transmitted to them, they will not escape the fate of death. In addition, because of their small size, crocodiles, lizards, turtles and other reptiles can survive by hiding from mosquitoes in caves and water. In fact, they can't escape extinction without caves and water. For example, Australian crocodiles that migrate between droughts often die from mosquito bites.

Third, from the archaeological research, Scientists have found bacteria in the guts of the cretaceous insects in amber that can cause leishmania and malaria-causing organisms that are deadly to dinosaurs.Traces of other protozoans, such as nematodes, flukes, and even dysentery, were also found in dinosaur droppings. These intestinal parasites can be widely spread through insect bites, indicating that dinosaurs die from infectious diseases caused by germs.In addition, the excavation of dinosaur fossils show that dinosaurs were in death, and many dinosaur eggs can't hatch, the extinction time lasted for one million years, some death was very pain, its performance is very similar with the plague, or only with plague can explain the phenomenon of death.

To sum up, there are a large number of deadly infecting mosquitoes in the age of dinosaurs. The dinosaur, an imperfected reptile of the immune system, has no immune ability after being bitten by mosquitoes and infecting bacteria,  eventually led to the extinction of the species that dominated the planet for more than 100 million years.

(Opinions of the writer in this blog don't represent those of China Daily.)




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