insect size will be very large

The researchers found that flying insects three hundred million years ago the reason that can grow to 28 inches, is because the oxygen content in the atmosphere is higher, can reach 30%, and today in the earth's atmosphere oxygen content of only 21%. Sufficient oxygen provides enough breathing for prehistoric flying insects, makes the movement organ flying insects become larger and more powerful, can provide more energy for flight. In a new study, paleontologist Matthew Clapham Clapham college is located in the Santa Cruz of California (Clapham) and her colleagues created a database, a collection of more than ten thousand species of prehistoric insects fossil samples, these insects are the age can be traced back to 320000000 years ago. Clapham believed that when the oxygen content in the atmosphere at a high level, insect size will be very large, if the oxygen content of the body decline, they will shrink, but the oxygen content is not the only explanation of prehistoric insects opened a huge volume of mystery. About 150000000 years ago, dinosaurs of the Jurassic era gradually evolved early birds, which is a giant flying insects nemesis, after such as moths, butterflies and insects have wings guy stopped growth, but when the oxygen content of the atmosphere also is in a higher level. According to this argument, we can find that oxygen is an important constraint on prehistoric insect evolution, limiting the flying insects the size limit, but in the birds appeared after flying insects began to appear natural enemies, so the bird has become a restricting factor of insect body constraint.