This paper takes part in the series essay competition of “great science” of Recordunkown.
The earth was born 4.6 billion years ago. After a series of adventures, the earth is very lucky to be a living planet. Therefore, life on earth may have appeared 4 billion years ago. After the birth of life, through continuous evolution and evolution, life forms become more and more complex, and then there is a rich life world.
There are billions of years in the life history of the earth, but the time when life really began to enrich was about 300 million years ago, that is, the era of Carboniferous Fantasy (about 250-300 million years ago). There is another name for this period: the age of giant insects. Since it is the age of giant insects, it shows that the overlord of this period is our common insect now.
For insects, I believe we are not unfamiliar with dragonflies, butterflies, ants, centipedes, mosquitoes and so on. They are the largest biological group in the world. But we can see that modern insects are relatively small, larger is dragonflies, and dragonflies are beneficial insects in the eyes of modern people. They are very beautiful and rare insects.
However, many people would not think that the Carboniferous era 250 million years ago was dominated by insects. As we all know, non intelligent life in nature must have a strong physique if it wants to be a dominant creature. For example, in the age of dinosaurs 65 million years ago, dinosaurs relied on their strong body to stand at the top of the food chain and become the dominant of the earth at that time.
250 million years ago, insects were able to dominate the biological world, indicating that insects were relatively large at that time. That’s right. In the Carboniferous era, people and insects were extremely huge. Let’s take dragonflies as an example. Today’s dragonflies are only about 5cm long and very small. However, in the Carboniferous era, the ancient giant dragonflies, including wings, were nearly 1 meter long, about 20 times as long as modern dragonflies. Such a huge dragonfly can carry a person to fly.
I believe everyone has seen the film “adventures in the center of the earth”. After the hero accidentally falls into the underground world, the insects there are also extremely huge. Bees are the size of dogs, carrying the hero to fly. According to scientists, at that time, the food of ancient giant dragonflies was land creatures, as well as some amphibians living in water, which could eat carnivores.
In the age of giant insects, dragonflies were not the largest insects. On land, the centipede, which we are familiar with, was nearly 2.5 meters long, and was also the Largest Arthropod in the evolutionary history of the earth. There are abundant animal and plant fossils in the Jurassic Daohugou fossil bed in Ningcheng, Inner Mongolia, China, including nearly 20 species of dragonflies, which are world-class fossils.
Chinese scientists discovered a 200 million year old fossil dragonfly in Junggar basin, Xinjiang. The largest wing span in the fossil “giant Dragonfly” is 710 mm, which is only slightly smaller than the Zhao’s repair Dragonfly previously found in Inner Mongolia. From these fossil dragonflies, we can also imagine what it was like 250 million years ago: giant insects dominate the land, and other animals can only avoid them.
Some people may have said, was there no creature bigger than insects 250 million years ago? Of course not. In terms of biological size, insects were not the largest 250 million years ago. But why has it become an era of insect dominance? In fact, the reasons are not complicated. One reason is that insects are often in groups. The second reason is that insects are often more effective in fighting.
I believe that everyone will know, to ask what is the largest biological group in the world, I believe many people will answer that it is insects. Yes, the reproductive energy of insects is very strong, like ants, and ants are the most powerful in nature. They can lift food several times heavier than themselves. They are real Hercules.
Today, we have heard that ants often kill elephants, not to mention that insects 250 million years ago were more than 20 times larger than they are now. Even creatures larger than insects are hard to win in the face of insects and eventually become their food. Fortunately, insects didn’t dominate all the time. In the end, in the course of evolution, they kept getting smaller and smaller, becoming the size of insects we see now. So what’s the reason why insects were so huge 250 million years ago?
As for what caused them to become like this in the Carboniferous period, experts are still not clear, and there is no definite answer. However, through research, scientists have put forward two possible reasons for this. One reason is that at that time, the oxygen content of the earth was very high. Scientists say the amount of oxygen in the earth’s atmosphere is not a fixed number over billions of years, but has changed significantly.
250 million years ago, the oxygen content in the atmosphere reached an astonishing 35% or more. We should know that the oxygen content in the modern atmosphere is only 21%. The oxygen content is too high, which has a huge impact on the evolution and development of life. At that time, insects inhaled a lot of oxygen, so they became bigger and bigger, and became giant graupel free insects. However, this also restricted their flight and movement. Take dragonflies for example, they could not fly very high at that time. At most, they could only glide slowly at low altitude.
Another reason may be that the body structure of insects is relatively special. The exoskeleton structure of insects is close to the inner side of the body. If insects want to grow continuously, they need to molt constantly. However, we all know that the life span of insects is very short, which also limits the number of molting. Without more molting and growth times, coupled with the continuous reduction of oxygen content, insects are becoming less and less in evolution. Until now, they have become familiar to us.
Of course, scientists have only put forward a few possible answers to the reasons why the ancient insects were extremely huge and then shrinking. What is the final conclusion? It has not been determined yet. More ancient insect fossils need to be found. Only through more research on them can we finally determine the reason.
I believe that 250 million years ago, insects can become so huge, the reason may not be simple, perhaps in addition to high oxygen content, special body structure, there are other reasons. No matter what the specific reason is, it’s a good thing for humans that insects have become like this.
Just imagine, if insects 250 million years ago did not keep getting smaller but maintained their original size in the later evolution, there might not be an era when dinosaurs dominated. Insects rely on the number advantage, can completely defeat dinosaurs, and after the birth of human beings, because of the huge size of insects, will become the biggest threat to human survival.
Of course, insects are not all pests. Except for some beneficial insects, they will not easily attack human beings. For example, mosquitoes, which are very annoying to human beings now, will definitely be a disaster to human beings once they are more than 20 times larger than the current size. There are also poisonous insects like centipedes, which are more than 2 meters in size, and they are terrible enough. Finally, there are a large number of ants, and human survival will be more difficult.
The birth of human is very lucky, once the giant insects slowly evolved and become less and less, which can not form a threat to human beings. A giant dinosaur that threatened human existence 65 million years ago was also destroyed by an asteroid. The two major threats were removed, and mankind was born smoothly, opening a new era of hegemony. All this makes many people feel that it seems that there is a force dominating. As long as there are giant terrestrial creatures that can threaten the survival of human beings on the earth, they will not escape the fate of extinction by nature.
Guys, what do you think of this? Welcome to leave a message below to discuss and express your opinions.