  thumb|wing venation of meganeura monyi, redrawn after brongniart (1893, pl. xli)  meganeura is a genus of extinct insects from the carboniferous period approximately 300 million years ago, which resembled and are related to the present-day dragonflies. with wingspans of up to , m. monyi is one of the largest known flying insect species; the permian meganeuropsis permiana is another. meganeura were predatory, and fed on other insects. fossils were discovered in the french stephanian coal measures of commentry in 1880. in 1885, french paleontologist charles brongniart described and named the fossil "meganeura" (large-nerved), which refers to the network of veins on the insect's wings. another fine fossil specimen was found in 1979 at bolsover in derbyshire. the holotype is housed in the musÃ©um national d'histoire naturelle, paris. ==size== controversy has prevailed as to how insects of the carboniferous period were able to grow so large. the way oxygen is diffused through the insect's body via its tracheal breathing system puts an upper limit on body size, which prehistoric insects seem to have well exceeded. it was originally proposed (harlÃ© & harlÃ©, 1911) that meganeura was able to fly only because the atmosphere at that time contained more oxygen than the present 20%. this hypothesis was dismissed by fellow scientists, but has found approval more recently through further study into the relationship between gigantism and oxygen availability.{{cite journal |author= gauthier chapelle and lloyd s. peck |date=may 1999 |title= polar gigantism dictated by oxygen availability |journal= nature |volume= 399 |pages= 114â115 |doi= 10.1038/20099 |url= http://www.nature.com/nature/journal/v399/n6732/abs/399114b0.html |quote= oxygen supply may also have led to insect gigantism in the carboniferous period, because atmospheric oxygen was 30-35% (ref. 7). the demise of these insects when oxygen content fell indicates that large species may be susceptible to such change. giant amphipods may therefore be among the first species to disappear if global temperatures are increased or global oxyg
Carboniferous_insects Meganisoptera