Oxygen-Fueled Sky Giants: Ancient Griffinflies Dwarfed by Predators Eventually

Meganeuropsis permiana and other griffinflies reached wingspans over 70 cm in an oxygen-rich Late Carboniferous–Early Permian atmosphere, but recent research suggests insect size was shaped by multiple factors—oxygen delivery, flight mechanics, and ultimately predation by birds and other aerial predators— meaning the giant-insect era ended as skies filled with competitors and oxygen levels shifted.