Insects, also known as arthropods (invertebrate animals with external skeleton), are the most numerous group of organisms on the planet, with about a million species identified so far. The title of the heaviest insect in the world has many competitors, but of those the most-frequently crowned is the larval stage of the goliath beetle (largest insects on the earth), Goliathus goliatus, the top size of which is at least 115g and 11.5 cm. The largest confirmed weight of an adult insect is 71 g (2.5 oz) for a giant weta, Deinacrida heteracantha, although it is likely one of the elephant beetles, Megasoma elephas and Megasoma actaeon, or Goliath beetles, both of which can commonly exceed 50 g (3oz) and 10 cm (4 inch), can reach a higher weight. The largest insects that ever lived are members of the extinct dragon-fly order Protodonata, which means “early dragonfly”. The name “griffinfly” has been proposed for members of this order because important differences distinguish them from modern-day dragonflies.
Protodonata’s fossil (traces of ancient life to find out more about the life on earth) records range from the Late Carboniferous to the Late Permian periods of the Paleozoic era. This was about 300 million years ago, before the dinosaurs, which evolved during the Mesozoic era. The largest known species is the Late Permian Meganeuropsis permiana, with wingspans longer than 75 cm (30 in or 2.5 ft) and an estimated weight of over 450 (1lb) , similar to a crow. This is larger than any insect that has ever lived on land or in the air. The late carboniferous Meganeura is a species of similar size to Meganeuropsis. It is assumed that at the time of the Carboniferous, there were so many trees and other oxygen producing plants which helped with the oxygen supply needed for the survival of those larger insects. This is also confirmed by the fossil records (collective accumulation of artifacts fossilized all over the world).
Meganeura was a predator, feeding on other insects and even small amphibians. Its name means “large-veined” after the network of veins on its wings. Most fossils of Meganeura are just fragments of wings, although a few full wings and even fewer full body impressions have been found. The few body expressions dug up so far show a globose head, large mandibles, a large thorax, strong spiny legs and a long slender abdomen, like that of a dragon fly.