A large representative of the extinct dragonfly-like order of griffinflies is the largest known insect species to have ever lived on Earth
Life-size model of the Permian griffinfly Meganeura
Image credit: Gene McCarthy
The largest living insect species known to us today are the atlas moth (which sports the largest wingspan by area of 160 cm2 or 25 in2), the white witch moth (which has the largest wingspan of about 30 cm or 12 in), and the Goliath beetle, the heaviest insect at 115 g (41 oz)
Among them, the giant griffinflies such as Meganeura monyi and Meganeuropsis permiana are the largest known insect species to have ever existed
These creatures have a wingspan of about 75 cm (28 in) – about three times the wingspan of the atlas
Their maximum body weight is uncertain, with estimates varying between 34 g and 240 g, thus up to more than twice the size of the goliath beetle
Atlas moths have the largest wingspan, by area, of any living insect
Image credit: CocosBounty/Shutterstock
This is done by squeezing and cracking the exoskeleton, which is especially difficult in the case of cockroaches
In other insects, however, the exoskeleton is not always rigid, and different parts of the body may have different strengths
The strongest body parts of griffinflies, on the other hand, are the wings, and therefore they are the parts most likely to fossilize
Therefore, most of the fossil record of griffinflies consists of fragmentary specimens, with a few rare exceptions
A beautifully preserved fossil of a Meganeuropsis permiana, the largest insect known to have ever lived on Earth
Griffinflies flew in the skies of our planet for about 20+ million years during the Late Carboniferous and Late Permian periods about 317-247 million years ago, achieving a worldwide distribution distribution
Their genus is quite diverse, with new species frequently described by scientists
Not all of them were very large though – some were about the size of modern throats
Meganeura monyi was the first griffinfly to be described, based on a fossil wing about 12 inches long
It has an estimated wingspan of about 27 inches (about 685 cm) and was the largest insect known at the time of its description in 1895
In 1939, however, Frank Carpenter described Meganeuropsis permiana, based on an incomplete, but large, wing discovered in two parts
Carpenter estimated the wingspan of the newly discovered species to be 29 inches (about 75 cm)
A few years later, he described another new species of griffenfly, Meganeuropsis americana, with a wingspan similar to that of M
This species holds the record for the largest known insect to have ever lived
Size comparison of the largest Carboniferous arthropods
Image credit: Emily Stepp
What makes griffinflies reach their great size?
During the Late Carboniferous and Early Permian there existed vast forests of coal swamps that produced large amounts of oxygen as a result of photosynthesis
This created a hyperoxic atmosphere, with oxygen levels well above modern levels
The environment these giant insects lived in was very different from today
With higher levels of oxygen in the atmosphere, insects absorb more of it, allowing them to grow to giant body sizes
The anatomy of griffinflies shows a highly maneuverable flight capability that is very metabolically demanding and requires high levels of oxygen
During the Permian, however, oxygen levels began to decline, accompanied by increased aridity
Eventually, this could lead to the extinction of these giant insects
Modern atmospheric oxygen levels are too low to allow similar gigantism in active aerial predators
For as long as griffinflies have existed, they have actually ruled the air
Of course, this also contributes to their long existence and, according to some theories, even their body size