恐龙的灭绝原因 英文同上满意的话我会+10-15分哒

恐龙的灭绝原因 英文同上满意的话我会+10-15分哒
恐龙的灭绝原因 英文
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满意的话我会+10-15分哒

恐龙的灭绝原因 英文同上满意的话我会+10-15分哒
With regard to the reasons for the extinction of dinosaurs, it is still being studied. For a long time, the most authoritative view, and the extinction of the dinosaurs 6500 years ago about a large meteorite. According to the study, there was a 7-10 km in diameter asteroid will fall on the earth's surface, causing a large explosion, such as throwing a lot of dust in the atmosphere to form the Zhetianbiri House of Sand and Fog, led to the suspension of plant photosynthesis , And therefore the extinction of the dinosaurs.
Asteroid impact theory quickly gained the support of many scientists. In 1991, in Mexico's Yucatan Peninsula occurred in the discovery of a long period of the meteorite impact craters, the fact is further evidence of this point of view. Today, this view seems to have become a conclusion.
But there are also many people for such an asteroid impact on the skeptical, because the fact is: frogs, crocodiles and many other very sensitive to the temperature of the animals have resisted and survived the Cretaceous. This theory can not explain why only the dinosaurs died. To date, scientists have put forward for the cause of the extinction of dinosaurs have been no fewer than a dozen scenarios, more wealth to the dramatic and exciting, "said the meteorite collision," but it is one of them.
In addition to the "meteorite collision", the extinction of dinosaurs on the main point of view there are the following:
First, climate change, said. 6500 million years ago, the Earth's climate suddenly changes in the temperature dropped, resulting in decreased oxygen in the atmosphere so that the dinosaurs could not survive. It was also suggested that dinosaurs are cold-blooded, but with no hair or warm organ and can not adapt to the Earth's temperature dropped, were frozen to death of.
Second, the species, said the fight. End of the dinosaur era, first appeared in small mammals, these animals are rodent predators may feed to eggs. As a result of this lack of small animal predators, more and more and eventually eat up the eggs.
Third, continental drift, said. Geology Research shows that the survival of dinosaurs at the age of the Earth's only a piece of the mainland only, that is, "Pangea." Due to changes in the earth's crust, the continent took place in the Jurassic of the larger division and drift, leading to the environment and climate change, and therefore the extinction of dinosaurs.
Fourth, changes in the geomagnetic said. Modern biology shows that certain biological and magnetic fields related to the death. More sensitive to the magnetic field of biology, in the Earth's magnetic field changes, may lead to extinction. It seems therefore that the extinction of the dinosaurs may be related to changes in the Earth's magnetic field.
V. said angiosperm poisoning. End of the dinosaur era, the Earth gymnosperms gradually disappearing, replaced by a large number of angiosperms, gymnosperms contain these plants are not in toxic shape of a huge dinosaur odd food, intake of a large number of angiosperms led to the accumulation of toxins in the body Too much, finally the poison.
Six, said acid rain. The late Cretaceous period may have been under strong acid rain, soil, including in the trace element strontium, be dissolved dinosaurs through drinking water and food, directly or indirectly, strontium intake, acute or chronic poisoning, the last groups of the dead.
The reasons for the extinction of dinosaurs on the hypothesis that the above-mentioned far more than these. But these above-mentioned hypothesis in the scientific community has more supporters. Of course, each of the above, there is an imperfect place. For example, "climate change" does not clarify the causes of climate change. After inspection, some small dinosaurs in the Coelurosauria, with enough early against small mammals, so "species struggle to say" there are loopholes. In modern geology, the "continental drift theory" itself is still a hypothesis. "Angiosperms poisoning" and "acid rain" the same lack of sufficient evidence. As a result, the real cause of the extinction of dinosaurs, have yet to explore it further.
关于恐龙灭绝的原因,人们仍在不断地研究之中.长期以来,最权威的观点认为,恐龙的灭绝和6500万年前的一颗大陨星有关.据研究,当时曾有一颗直径7-10公里的小行星坠落在地球表面,引起一场大爆炸,把大量的尘埃抛如大气层,形成遮天蔽日的尘雾,导致植物的光合作用暂时停止,恐龙因此而灭绝了.
小行星撞击理论,很快获得了许多科学家的支持.1991年,在墨西哥的尤卡坦半岛发现一个发生在久远年代的陨星撞击坑,这个事实进一步证实了这种观点.今天,这种观点似乎已成定论了.
但也有许多人对这种小行星撞击论持怀疑态度,因为事实是：蛙类、鳄鱼以及其他许多对气温很敏感的动物都顶住了白垩纪而生存下来了.这种理论无法解释为什么只有恐龙死光了.迄今为止,科学家们提出的对于恐龙灭绝原因的假想已不下十几种,比较富于刺激性和戏剧性的“陨星碰撞说”不过是其中之一而已.
除了“陨星碰撞说”以外,关于恐龙灭绝的主要观点还有以下几种：
一、气候变迁说.6500万年前,地球气候陡然变化,气温大幅下降,造成大气含氧量下降,令恐龙无法生存.也有人认为,恐龙是冷血动物,身上没有毛或保暖器官,无法适应地球气温的下降,都被冻死了.
二、物种斗争说.恐龙年代末期,最初的小型哺乳类动物出现了,这些动物属啮齿类食肉动物,可能以恐龙蛋为食.由于这种小型动物缺乏天敌,越来越多,最终吃光了恐龙蛋.
三、大陆漂移说.地质学研究证明,在恐龙生存的年代地球的大陆只有唯一一块,即“泛古陆”.由于地壳变化,这块大陆在侏罗纪发生的较大的分裂和漂移现象,最终导致环境和气候的变化,恐龙因此而灭绝.
四、地磁变化说.现代生物学证明,某些生物的死亡与磁场有关.对磁场比较敏感的生物,在地球磁场发生变化的时候,都可能导致灭绝.由此推论,恐龙的灭绝可能与地球磁场的变化有关.
五、被子植物中毒说.恐龙年代末期,地球上的裸子植物逐渐消亡,取而代之的是大量的被子植物,这些植物中含有裸子植物中所没有的毒素,形体巨大的恐龙食量奇大,大量摄入被子植物导致体内毒素积累过多,终于被毒死了.
六、酸雨说.白垩纪末期可能下过强烈的酸雨,使土壤中包括锶在内的微量元素被溶解,恐龙通过饮水和食物直接或间接地摄入锶,出现急性或慢性中毒,最后一批批死掉了.
关于恐龙灭绝原因的假说,远不止上述这几种.但是上述这几种假说,在科学界都有较多的支持者.当然,上面的每一种说法都存在不完善的地方.例如,“气候变迁说”并未阐明气候变化的原因.经考察,恐龙中某些小型的虚骨龙,足以同早期的小型哺乳动物相抗衡,因此“物种斗争说”也存在漏洞.而在现代地质学中,“大陆漂移学说”本身仍然是一个假说.“被子植物中毒说”和“酸雨说”同样缺乏足够的证据.因此,恐龙灭绝的真正原因,还有待于人们的进一步探究.