Scientific discoveries of prehistoric giant insects wingspan of up to 70 cm

300 million years ago, a giant dragonfly with a wingspan of up to 76 cm.

Insects regarded as one of the tiny creatures on Earth, the wingspan of the largest insects, butterflies and moths, but a 20-30 cm, 300 million years ago, giant insects everywhere, one of the most magical should be a giant dragonfly, and their wingspan can reach 70 cm, is the history of the largest insects on Earth.
Ancient times, the oxygen content in the Earth's atmosphere far beyond today's standards, a long time, scientists have speculated, perhaps the change of the atmospheric oxygen content plays a key role in their rise and fall. Now, paleontologists began to explore the size and the eagle quite ancient dragonflies, cockroaches and other ultra-insects rise and fall with a high oxygen content, is not the high-oxygen atmosphere created ancient giant insects? Not long ago, from Santa Cruz, University of California paleontologist - Matthew Kulubomu, and colleagues confirmed this speculation.
Paleontologist - Matthew - Kulubomu and colleagues to establish a huge database of fossil insects, they collected 10,500 insect fossil samples since 320 million years ago since, the report pointed out that the Carboniferous period when the Earth's atmosphere of oxygen concentrations up to 35%, much higher than the current 21 percent, many arthropods through direct absorption of oxygen throughout their body in the micro-trachea, rather than indirectly through the blood to absorb oxygen, high oxygen content has encouraged insect evolution to the big head direction . At the same time they found the fossil record, when the oxygen content increased, the size of insects will become larger, and vice versa.
Giant dragonfly insects is the representative of this period, 300 million years ago, these species once prosperous moment, but after about 5000 years, from the Permian of the mid to late due to the emergence of birds originator, to break the giant insects "King era," the bird, is a disaster for the giant insects, the report said the rise in oxygen content could not let the insect's body continues to change, but narrowed.
Matthew asked: "The current debate is, oxygen is a very important factor for the insect body, but since the appearance of a bird, it is obvious they are more to limit insect size constraints. So why the giant insects lost the bird?
Matthew added: "the flexibility of flying creatures are measured by the body, based on this point, the small size flying objects flying objects than the large size advantage, in other words, the relatively clumsy giant insects more easily become prey Another point may be a bird to occupy these giant insects lunch, while the dragonfly is predatory insects in the Permian in the late giant dragonfly is likely for the same food competition with these birds, birds and flexible advantages for their richer food, long gorgeous wings of a giant dragonfly, but dwarfed ".
The strange thing is, in a flying reptile fossil hunting food, the researchers did not find any signs of insect fossils, and other words, these giant insects and birds are predators, then what is the reason to cause them to extinction, scientists are still difficult to answer.