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When most people think of giant dragonflies, they envision monstrous insects soaring through ancient skies.
While these creatures are often referred to as “giant dragonflies,” they were not true dragonflies.
Instead, they were part of a more primitive group of insects called griffin flies or Meganisopterans, which dominated the skies long before the age of the dinosaurs.
Their time on Earth was brief but remarkable, stretching from the Late Carboniferous to the Late Permian period, roughly 317 to 247 million years ago.
Let us see what we know about Meganeura.
Discovery of Meganeura Fossils
The uncovering of Meganeura fossils began in France in 1880 when the first remains of these ancient insects were found.
Just a few years later, in 1885, French paleontologist Charles Brongniart officially described and named the species Meganeura, making it a significant discovery in paleontology.
In 1979, another well-preserved fossil of this prehistoric insect surfaced in Bolsover, Derbyshire. This further solidified the place of Meganeura in the fossil record, highlighting the vast reach of these ancient creatures.
- Large, predatory insects
- Superficially similar to modern dragonflies and damselflies
Among the most impressive species in this family was Meganeuropsis, particularly the type species Meganeuropsis permiana.
As its name suggests, this species thrived during the Early Permian period. It exhibited:
- A wingspan of around 28 inches
- A body length of approximately 17 inches
These characteristics made Meganeuropsis one of the most formidable insects of its time.
How Did These Insects Grow So Large?
One of the most intriguing mysteries about Meganeura and its relatives is how they grew to such enormous sizes, far surpassing modern insects.
Several factors played a role in enabling these prehistoric giants to thrive.
Modern insects are limited in size due to the way oxygen is transported throughout their bodies. They rely on a tracheal breathing system, which delivers oxygen directly to tissues through a network of tubes, placing a natural limit on how large they can grow.
- Higher oxygen levels: The atmosphere during the Carboniferous period contained up to 35% oxygen, significantly more than today’s 20%. This higher oxygen concentration allowed these insects to grow larger than any modern insect could under current atmospheric conditions.
- Lack of aerial predators: Without vertebrate predators dominating the skies, pterygote insects such as Meganeura were free to grow unchecked, facing little threat from other creatures.
- Evolutionary “arms race”: Another possible explanation for their size is an evolutionary competition between plant-eating insects like Palaeodictyoptera and their predators, such as the griffinflies. This “arms race” likely pushed both groups toward larger body sizes.
- Aquatic larval stage: Some scientists also suggest that these insects’ development in water as larvae contributed to their immense size. Growing larger during their aquatic stage may have helped them adapt to higher oxygen levels while avoiding predators before transitioning to their terrestrial adult forms.
These factors, combined with the unique conditions of the prehistoric world, allowed Meganeura and other griffinflies to become some of the largest flying insects ever to exist.
Interesting Traits and Behavior
Although often compared to modern dragonflies due to their similar appearance, Meganeura and its relatives had several key structural differences:
Wing Structure
Their wings were heavily veined and reinforced with cross braces, unlike the delicate wings of today’s dragonflies.
This extra strength allowed them to maintain stability in flight despite their large size. The name “Meganeura” means “large-veined,” referring to the distinct vein patterns in their wings.
Vision
These massive insects had large, multi-faceted eyes, giving them excellent vision for spotting prey during flight. Their vision was likely one of their primary tools for hunting.
Leg Spines
Meganeura’s legs were equipped with spines, which they used to grasp prey like modern dragonflies. However, their larger size likely made them capable of hunting a broader range of organisms.
In terms of reproduction, male griffinflies would latch onto females using specialized appendages at the front of their bodies during mating.
Despite their impressive size and power, these ancient insects were eventually driven to extinction. This was likely due to the drastic reduction in atmospheric oxygen levels at the end of the Permian period.
Oxygen Levels
Modern oxygen levels hover around 21%, far lower than the 35% oxygen content during the Carboniferous period. With this reduction, the tracheal breathing system of Meganeura could no longer support their massive bodies, contributing to their demise.
The Legacy of Meganeura
Although extinct, griffin flies like Meganeura are remembered as some of the largest and most awe-inspiring insects to ever exist. With their impressive size, they towered over most modern-day flying insects.
- Wingspans reaching up to 28 inches
- Body lengths extending over 17 inches
These ancient giants dominated the skies, offering a window into a time when the atmosphere supported creatures far larger than anything alive today. Their fossilized remains provide invaluable insight into this prehistoric era.
Despite their extinction, Meganeura’s remarkable size and evolutionary significance continue to captivate both scientists and insect enthusiasts.
Summary
The story of Meganeura and other Meganisopterans serves as a fascinating reminder of the ever-changing dynamics of life on Earth.
It illustrates how creatures of immense size once thrived in a world vastly different from our own.
