Zhang Haichun team found in the Junggar Basin, the original dragonfly fossils (respondents for the map)
summer is about to pass, we have to bid farewell to the hot sun, floral small skirt, In addition, I am afraid even occasionally across the sky dragonflies have to see.
“Jasper eye mica wings, lighter than butterfly thin bee.” People in the impression of dragonflies, small and light, or elegant in the flowers, or light on the water. As everyone knows, in hundreds of millions of years ago, small and lovely dragonfly was also the air “giant.” Currently found the largest dragonfly, the fin exhibition up to 710 mm, living in the early 280 million years ago the early Permian, is the world’s largest known insects. So, what is the reason for these light flying master in hundreds of millions of years ago to have such a huge body?
Dragon is a kind of ancient insects, the earliest can be traced back to 320 million years ago.
Taxonomy, the dragonfly head is divided into extinct ancient dragonfly head, the original dragonfly head, and the modern dragonfly head three categories. From the time point of view, the three are the orderly evolution of the relationship: the ancient dragonfly head only survived in the late Carboniferous early; the original dragonfly head appeared in the Late Paleozoic and end of the Triassic end; dragonfly head appeared in the Permian, Jurassic The radiation, the descendants have continued to this day.
The ancient dragonflies are much larger than we imagined. Its appear in the 300 million years ago, to the Mesozoic period, the dragonfly’s head has gradually become larger, became the air “dominant.” As a predator of animals, their main food is a variety of insects, as well as some small vertebrates, such as young lizards, is the letter of the meatless.
So, when the air “overlord” who’s how big it?
mouth that no, fossil as evidence. According to the Chinese Academy of Sciences Institute of paleontology researcher Zhang Haichun, one of the team members, the University of Hong Kong doctoral students Zheng large burning, led by Zhang Haichun team in our Junggar Basin northwest edge found a 200 million years ago, the original dragonfly fossils. This new discovery of the original dragonfly wing length 101 to 102 mm, wing width of 210 mm (A4 paper short side of the length), is China’s Mesozoic is currently known as the second largest dragonfly fossils.
The same is Zhang Haichun team, a few years ago in Inner Mongolia Ningcheng Jurassic Road tiger ditch fossil layer, also found a preserved nearly complete dragonfly forewing fossils, wing length 107.6 mm, width 14.3 mm, accordingly Inferred that the dragonfly wingspan of 225 mm, is the largest species of known dragonfly head, but also the world’s fourth largest dragonfly.
What is more, in the United States found the early Permian Pinot Noir pawl of the wing show up to 710 mm.
“Big Mac” is contributed by the oxygen content
Why the dragonfly’s ancestors look so sturdy? For a long time, scientists have speculated that perhaps changes in the oxygen content of the atmosphere play a key role in their rise and fall.
Zheng said: “Because the late Paleozoic (300 million years ago) a large number of tall plants began to appear, the formation of a wide range of forests, resulting in increased oxygen content of the Earth.” Paleozoic atmospheric atmosphere Oxygen content of 27% -35%, and now the Earth’s atmospheric oxygen content of about 21%.
The dragonflies are “breathing” through their body’s stomatal system, rather than indirectly absorbing oxygen through the blood. The stomata are attached to the trachea, and the stomata Oxygen is given to the body. At the current level of oxygen, the total length of the modern dragonfly airtight system has reached its limit; beyond this limit, the level of oxygen will become insufficient. Therefore, in the high concentration of oxygen environment, the total length of the dragonfly porosity system will be longer, the head will be even greater.
A new study by the University of Arizona shows that the cultivation of dragonflies in high-oxygen environments (oxygen over average) can make their bodies larger. Although they did not cultivate the wings of nearly 1 meter of dragonflies, but the dragonfly body size increased by 15% is already a very interesting discovery.
Body size and oxygen content is not necessarily linked
Although the oxygen led to the ancient dragonfly was made by the scientists justified, but some scientists still feel puzzled, and some also made The opposite conclusion.
Insect researcher at the University of Arizona, Jon Harrison and colleagues, put some of the modern insects with their own ancestors with air holes in the oxygen-rich environment, the results found that higher oxygen content did not produce more Large individuals, and lower oxygen levels did not produce smaller individuals.
Harrison explained that insects can adapt to changes in oxygen concentrations through a variety of skills. These skills include increasing stomata and increasing the number of stomata, and some of these insects are better at the former and others are better at the latter. It is precisely because of this, it makes the scientists on the prehistoric insect “huge disease” has a different answer. In addition, through the study of fruit flies, scientists found that some fruit flies in the high oxygen environment, increased size, and some did not. But in the high oxygen content, high pressure is the environment, to acceptThe experimental Drosophila living to the fifth generation, the body size increased by 20%. Does this explain the level of pressure is also related to the size of insects? The inconsistency of these experimental results can not help but people on the oxygen created the ancient giant dragonfly conquest doubt.
However, the oxygen content is not the only explanation for the huge mystery of prehistoric dragonflies. Scientists have pointed out that the late Paleozoic to fly vertebrates have not yet appeared, dragonflies lack of competitors and natural enemies, so free to grow and become the air “giant.” With the pterosaurs (210 million years ago), birds (150 million years ago) and bats (533 million years ago) have emerged, the slow movement of the “giant dragonfly” due to flight Flexible, more powerful natural enemies of the suppression and gradually extinction. To the late Jurassic, the original dragonfly head has disappeared, dragonfly head appears, the body is getting smaller and smaller, until today are not much change.
The larger flying insects are less agile than their own, so that these “big insects” can easily become the predator of early birds, which leads to the early birds after the emergence of dragonflies, etc. The wings of the insects stopped growing, but the oxygen content of the atmosphere was still at a high level. Another point is that the birds occupy the giant insects of the lunch, giant dragonfly is likely to compete with the same food for the birds, the bird’s flexible advantage for them to bring a richer food, and giant dragonfly long gorgeous wings, But it is dwarfed. But no matter what kind of may have shown that natural enemies may be another factor affecting the dragonfly body.
It seems that for the ancient dragonflies why such a huge puzzle, I am afraid that scientists have yet to find more adequate evidence Caixing. In addition to the huge dragonfly, there are many monsters, but also a lot of monsters, but also a lot of monsters, Maybe most people will think of dinosaurs. However, the dinosaur is just one of the following let us come together to understand these prehistoric beasts it
Melville whale is the largest of the Leviathan whales, belonging to the sperm whale. A total length of 18 meters, just 35 cm of teeth, the shark in its mouth is a one of the appetizers.
Titan python length of up to about 15 meters, weighing more than 1 ton, these two figures have been enough to explain their terrible place. It was extinct 58 million years ago, looks like a modern python amplification version.
fear crocodile, also known as muscle crocodile, imperial crocodile, is a kind of extinct crocodile. They live in the early Cretaceous Africa, is one of the largest surviving crocodile animals. Almost twice as long as the current saltwater crocodile, weighs about 8 to 10 tons.
The shrimp is the archaeological period of the Cambrian, probably the first of the earth’s overlord, 500 million years ago at the top of the sea food chain. Its body size can grow to 2 meters, light mouth device on more than 25 cm.
Bron of mine called scorpion scorpion is a scorpion living in water, the average length of a meter and more, up to twenty-three meters, was the water predators.
The head of the tortoise is as big as the football, the body is bigger than the car, the sharp beak and the thick claws are its predator.