300 million years ago…

300 million years ago insects could get really big. Millipedes and centipedes could get larger than humans, dragonflies as big as eagles, beatles the size of a large dog.The leading theory is that ancient bugs got big because they benefited from a surplus of oxygen in Earth’s atmosphere. And the leading theory on why there was so much O2 is that trees were new on the scene and were able to grow because of lignin. But lignin could not be consumed by anything in that era so trees kept putting oxygen in the atmosphere but didn’t “balance the books” by releasing CO2 when they died.
They also believe this process led to the greatest mass extinction on the planet.

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