I remember once seen a documentary, documentary portraying scientists believe that alien appearance, the appearance of an alien body with their living environment has a great relationship, for example, it is assumed alien planet inhabited gravity is relatively large, gravity could prompt it becomes very short. Conversely, if extraterrestrial life is like living on the moon gravity as small stars, so many years of evolution, it may be its size will become very tall.
In fact, the reason is not only applicable to the alien, for any kind of life is the same in the long process of evolution, as well as the volume of organisms characterized planet will live with the changes and evolution. However, in the long history of the evolution of life on Earth which, for some time, it seems a bit different, that is approximately between Carboniferous and Jurassic geology familiar friends will know, when the volume of animals, is simply amazing big.
Random example, we know there is an animal called dragonfly, its volume is small, probably only half as big as the palm, often walking in many plants. However, we may not know is that in the Carboniferous period, the size of the dragonfly is now seven to eight times, and now the Eagles probably about the same size. At that time, the ground crawling scorpions and many insects are also in the volume of more than one meter.
During that period, there is an animal that most people are familiar with dinosaurs, people all over the world its size probably are not familiar with, can be regarded as the world's largest monster, and there are also smaller dinosaur weighing several tons, several meters high for some herbivorous dinosaurs, whose length sometimes staggering two meters, equivalent to the height of five-six floors. However puzzling is that the Earth's gravity that time there was no unusual small, but then land animals but had surprisingly tall, just today we can not see such a big volume of several animals. So in the end this is how it happened?
Originally, dating back some 200 million years ago, when the outbreak of violent volcanic activity on so that when the carbon dioxide content of the volcano on Earth surge, causing the greenhouse effect. In this case, the entire planet will soon become a warm and humid "rainforest" to increase vegetation also makes the oxygen content of the atmosphere was unusually rich on land, which is about 1.5 times today, this situation also when many large herbivores provided plenty of food. United under these various conditions, the volume of animals will suddenly increase that reached a peak. So, in that period of the animal, and why such a large length, the fundamental reason is because the atmospheric oxygen content is too rich.
(Author: Lai chongda)
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