Méganeura
Meganeura monyi is an insect Fossile Carbonifère (between - 280 and - 230 million years) having the aspect of a giant Libellule.
Aspect
Its dimensions were gigantic: its length was from approximately 1 m, its scale exceeded 80 centimetres and its weight is estimated at 150 grams. Meganeura monyi is one of the larger insects which ever existed on the Earth (even if the species of the Permien, Meganeuropsis permiana is also a serious candidate).
Lifestyle
The paleoecologic reconstitutions indicate that its medium of life consisted of tropical forests, near rivers or other points of water.It was a predator which probably nourished other insects and small Amphibians that it caught by bite, whereas the current dragonflies use their legs.
Layers
Fossils of Meganeura were discovered in the coal mines of Commentry (Allier) in 1880. Five years later, the French paleontologist Charles Brogniart described it and its name gave him.Another remarkable specimen was discovered in Bolsover, in the Derbyshire, in 1979.
The Holotype is with Paris with the National Muséum of Natural history.
Too much large to breathe in the current atmosphere?
Controversies are high on the question of knowing how the insects of carboniferous had been able to become also large. The way in which the dioxygene diffuses through the respiratory system trachéal imposes on the size of the body a maximum limit (cf: Respiration of the insect), that however the insects of carboniferous however seem to have exceeded. Initially it was proposed that Meganeura could fly owing to the fact that at that time, there was more dioxygene in the atmosphere than the twenties and one current percent. This theory had been thereafter abandoned, but it found credit very recently thanks to later studies on the relation between gigantism and the availability in dioxygene. If this theory is correct, these giant insects would have been dangerously sensitive to the sudden decrease of the levels of dioxygene, and of course they would not have been able to survive in our atmosphere.
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