Do you get the shivers when a bee or, even worse, a flying cockroach comes your way?
Now, imagine a dragonfly the size of a hawk or stepping over a millipede as long as your car. Sounds like a scene from a prehistoric thriller, doesn't it?
Is it true that insects were once much larger than they are today?
VERDICT:
TRUE
This giant insect scenario was once a reality on Earth.
Fossils show that giant dragonflies and huge cockroaches were common during the Carboniferous period or the late Paleozoic Era.
So, what caused these creepy-crawlies to grow so large, and why aren't they around to star in nature documentaries today?
One main reason is tied to oxygen levels. During that era, the Earth's atmosphere had significantly higher oxygen levels.
The growth of vast forests removed significant amounts of carbon dioxide, resulting in atmospheric oxygen levels potentially reaching 35%, compared to today’s 21%.
This oxygen-rich environment allowed insects to grow larger because their respiratory systems could support bigger body sizes.
Another reason is the lack of aerial predators. These giant bugs had free rein of the skies. But when birds and other flying predators appeared, the advantage of being large diminished, leading to a natural selection for smaller, more agile insects.
While we won’t see giant dragonflies swooping down on us today, the fossil evidence of these enormous insects reminds us of a time when Earth was very different.
Who knew that a little more oxygen could turn the bug world into a land of giants?
SOURCES
https://www.science.org/content/article/where-have-hawk-sized-insects-gone
https://news.ucsc.edu/2012/06/giant-insects.html
