恐龙是怎样灭绝的 英文表达

恐龙是怎样灭绝的 英文表达
恐龙是怎样灭绝的 英文表达

恐龙是怎样灭绝的 英文表达
How did the dinosaurs become extinct?This is a question that has stumped scientists ever since dinosaur fossils were first discovered.There are many theories as to how the dinosaurs became extinct.This page presents some of the most popular thoeries.Keep in mind that there is no absolutely proven theory.Noone knows for certain exactly why and how the dinosaurs became extinct.
Probably the most popular theory right now is the Asteroid Theory.According to this theory a large asteroid or comet collided with Earth about 65 million years ago.Scientists think that such a large collision would throw so much dust into the air that sunlight would not be able to shine and plants and animals would die.The dramatic changes in climate that resulted from this huge collision were too much for the dinosaurs.They were not able to survive.
Another theory that could explain how the dinosaurs became extinct is volcanic activity.A huge increase in volcanic activity at around 65 millions years ago could have pumped so much ash into the air that it blocked out the sun killing the dinosaurs.
Some scientists believe that there was a severe ice age.Throughout Earth's history there have been many ice ages.The last one ended about 10,000 years ago.A very severe ice age could have changed temperatures and frozen a lot of Earth's water.The dinosaurs would not be able live under such conditions and that is how the dinosaurs became extinct.
It has also been suggested that desease killed off the dinosaurs.A very deadly and contagious desease may have circulated among the dinosaurs forcing them to become extinct.
Still yet another theory is that the Earth just gradually changed in climate over a long time period and the dinosaurs were not able to adapt to the cooler,dryer climate.
There are probably other theories as to how the dinosaurs became extinct.One thing is for certain.All dinosaurs that we know of are extinct.How did all the dinosaurs become extinct?Maybe one of these theories is the right answer.However,it is difficult to explain why all the dinosaurs died out but many other animals survived.Perhaps one day we will know for certain how the dinosaurs became extinct.Until then we must speculate and continue the search for the answer to this great mystery of nature.

How did the dinosaurs become extinct? This is a question that has stumped scientists ever since dinosaur fossils were first discovered. There are many theories as to how the dinosaurs became extinct. ...

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How did the dinosaurs become extinct? This is a question that has stumped scientists ever since dinosaur fossils were first discovered. There are many theories as to how the dinosaurs became extinct. This page presents some of the most popular thoeries. Keep in mind that there is no absolutely proven theory. Noone knows for certain exactly why and how the dinosaurs became extinct.
Probably the most popular theory right now is the Asteroid Theory. According to this theory a large asteroid or comet collided with Earth about 65 million years ago. Scientists think that such a large collision would throw so much dust into the air that sunlight would not be able to shine and plants and animals would die. The dramatic changes in climate that resulted from this huge collision were too much for the dinosaurs. They were not able to survive.

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In 200 million years ago, a large number of Mesozoic reptile on land, so called "the Mesozoic and reptiles," the earth is first vertebrate widely. Then the earth's climate is warm, the thick forest an...

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In 200 million years ago, a large number of Mesozoic reptile on land, so called "the Mesozoic and reptiles," the earth is first vertebrate widely. Then the earth's climate is warm, the thick forest and reptiles had enough food, gradually flourish, more and more kinds. They are constantly to differentiate into different categories of reptiles, some became today, some turtles became today's alligator, some became today's snakes and saurians, has evolved into a kind of mammals across the world today.
Dinosaurs were all reptiles in the biggest category, physical life is suitable in the marshes and shallow lake, warm and wet, the air is also very easy to find food. So the dinosaurs on earth millions years of rule, but somehow, in 65 million years ago, a very short period of time, and today people died out suddenly see only then leave of dinosaur fossils.
The reasons about the extinction of the dinosaurs, people still continuously research. Long-term since, the most authoritative view, the extinction of the dinosaurs and 65 million years ago, a large meteors. According to the study, there was a 7-10 kilometers in diameter of the asteroid crashed on the earth's surface, causing a huge explosion, send a lot of dust into the atmosphere, such as cloud formation in dec.15 plant photosynthesis and temporarily stopped, dinosaurs extinct.
An asteroid theory, soon won the support of many scientists. In 1991, in Mexico's Yucatan peninsula found a bygone era in the meteors, this fact impact craters further confirmed this view. Today, this seems to have good.
But there were also many people on the theory of an asteroid scepticism because the fact is: frogs, crocodiles and many other sensitive to temperature, the animals worked cretaceous and survive. The theory fails to explain why only death. The dinosaurs, So far, the scientists suggest the extinction of the dinosaurs reasons for not imaginary has dozens of comparison, stimulating and dramatic "full collision said." but the meteorites are one.
Besides "the meteorite collision", the main ideas about the extinction of the dinosaurs have the following kinds:
A, climate change. 65 million years ago, the earth's climate change, temperature sudden drop sharply, atmospheric oxygen levels drop, make the dinosaur cannot survive. There are also people who believe that dinosaurs are cold-blooded, no hair or heat preservation organ, cannot adapt to the earth, have been frozen.
Second, the species struggle. In the end, the first dinosaur small mammals, these animals of rodents predators, may to feed dinosaur egg. Due to the lack of small animals, more and more natural, finally ate the dinosaur egg.
Third, continental drift. Geology research proves, in the time of the dinosaurs of the mainland, namely "only a generic ancient land." Due to the changes in the continental crust, of the Jurassic and drift phenomena split larger, eventually leading to environment and climate change, the dinosaurs and extinction.
Four, geomagnetic change said. Modern biology, some biological magnetic field of death and relevant. The biological magnetic field is more sensitive to changes in the earth's magnetic field, may cause extinction. By inference, the extinction of the dinosaurs may change with the magnetic field of the earth.
Five, the angiosperms poisoning. In the end, the dinosaurs on earth gymnosperms disappearing, replaced by a large number of angiosperms, these plants containing gymnosperms have no toxin, form a huge dinosaur food intake, thrashing angiosperm cause body endotoxin accumulation overmuch, finally was poisoned.
Six, acid rain. Late cretaceous may have strong acid rain, soil microelement, including strontium being dissolved by water and food, the dinosaurs, directly or indirectly, strontium intake of acute or chronic poisoning, the last batch died.
The reasons about the extinction of the dinosaurs, far above the hypothesis. But above all, scientists in several hypothesis has more supporters. Of course, there is every imperfect places. For example, "the climate change said." not illustrate reasons of climate change. Some of the investigation, the small dinosaur bone dragons and virtual as small early mammals, therefore "rival struggle" also exist species loopholes. But in the modern geology, the theory of continental drift ", "itself is still a hypothesis. "The angiosperms poisoning" and "rain" also lack sufficient evidence. Therefore, the real reason for the extinction of the dinosaurs, there is a need for further exploration of.

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在两亿多年前的中生代，大量的爬行动物在陆地上生活，因此中生代又被称为“爬行动物时代”，大地第一次被脊椎动物广泛占据。那时的地球气候温暖，遍地都是茂密的森林，爬行动物有足够的食物，逐渐繁盛起来，种类越来越多。它们不断的分化成各种不同种类的爬行动物，有的变成了今天的龟类，有的变成了今天的鳄类，有的变成了今天的蛇类和蜥蜴类，其中还有一类演变成今天遍及世界的哺乳动物。
恐龙是所有爬行动物中体格最...

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在两亿多年前的中生代，大量的爬行动物在陆地上生活，因此中生代又被称为“爬行动物时代”，大地第一次被脊椎动物广泛占据。那时的地球气候温暖，遍地都是茂密的森林，爬行动物有足够的食物，逐渐繁盛起来，种类越来越多。它们不断的分化成各种不同种类的爬行动物，有的变成了今天的龟类，有的变成了今天的鳄类，有的变成了今天的蛇类和蜥蜴类，其中还有一类演变成今天遍及世界的哺乳动物。
恐龙是所有爬行动物中体格最大的一类，很适宜生活在沼泽地带和浅水湖里，那时的空气温暖而潮湿，食物也很容易找到。所以恐龙在地球上统治了几千万年的时间，但不知什么原因，它们在6500万年前很短的一段时间内突然灭绝了，今天人们看到的只是那时留下的大批恐龙化石。
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。

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