About 350 million years ago, dragonflies soared through the skies with wingspans of up to 27 inches (70 centimeters). For years, scientists believed that high oxygen levels in the atmosphere allowed these massive insects to thrive. But a new study challenges this long-standing idea, suggesting we might need to rethink why insects like the griffinfly went extinct.
In a 1995 article in Nature, researchers linked increased atmospheric oxygen to the growth of giant insects, a theory that persisted for nearly three decades. Recently, however, a team of international scientists published findings that question this connection. They argue that insect flight muscles can function well today, even with lower oxygen levels. This means the mystery of insect gigantism isn’t solved yet—there’s still much to discover.
The researchers state that there’s no physiological reason insects couldn’t fly today if they were the size of griffinfly. Yet, ironically, they don’t exist anymore. One major idea is that oxygen levels during the time of giant insects were higher—around 9% more than today. This seemed to support the notion that oxygen directly influenced their size.
However, a closer look at insect biology reveals a fascinating twist. Insects have a unique respiratory system called the tracheal system. This network of air-filled tubes efficiently delivers oxygen directly to their muscles. A study led by Roger Seymour, a biologist at Adelaide University, showed that flying insects use very little of their muscle space for this system—only about 1%. In contrast, similar structures in birds and mammals take up ten times more space.
This discovery suggests that insects have the potential to grow larger without being hindered by their oxygen supply system. Seymour noted that insects could potentially adapt by increasing the number and size of their tracheoles, enabling them to sustain a larger body size.
So, if conditions were right, giant insects could exist today. The researchers caution, however, that while oxygen levels are crucial, other factors might also play a role in limiting the size of modern insects. For example, larger species often face more significant extinction risks. During the era of the griffinfly, there were no birds or mammals to compete with or prey on them.
Overall, the story of these massive insects highlights the adaptability of insect biology. Their past continues to inspire curiosity, suggesting there’s much more to learn about the interactions between evolution, environment, and survival.
For more insights on ancient ecosystems and the evolution of life on Earth, check out this study.
Source link
entomology,Geochemistry,Paleobiology
