Carboniferous coal forests

c. 310 million years ago · Event

Vast swamp forests of scale-trees and giant horsetails blanket the tropics, burying so much carbon they will become most of the world's coal — and pushing oxygen so high that insects grow monstrous: Meganeura, a dragonfly with the wingspan of a hawk, and millipedes over two metres long. The first amniotes scurry beneath them.