As pointed out on here... and these six times larger dragonflies have NO adaptation for their larger size... no proportionately larger wings, which are only 36 times larger surface area to support the dragonfly's 216 times heavier weight, no larger muscle attachment points on their exoskeletons to support the larger muscle engines needed to lift the dragonfly with its far heavier weight ... this flies in the face of logic.
Something was different about conditions that allowed dragonflies of this size to live and fly. What?
Yes, that is the question. My thought was as follows: Since insects are limited in size by their respiratory system, not their weight, and these six times larger insects have NO [structural] adaptation for their larger size, whatever was different about their environmental conditions had to increase the efficiency of their respiration.