How did ancient bugs get so big? The prevailing theory may be wrong.
Flying insect respiratory systems suggest abundant oxygen can’t explain ancient gigantism.
About 300 million years ago, giant dragonflylike insects with half-meter wing spans buzzed through hot and swampy forests on the former supercontinent of Pangaea. Scientists have long debated what allowed griffenflies, as they’re known, and similar fearsome flying bugs to grow so big during the Carboniferous period. The atmosphere at the time held more oxygen than it does today, and the textbook hypothesis suggests these giant insects developed more respiratory tubes to deliver that gas to their muscles, enabling them to grow and grow. But a new analysis of the anatomy of insect flight muscles, published last week in Nature, undercuts that idea, suggesting past ferocious fliers didn’t incorporate oxygen into their muscles any more generously than their smaller counterparts do today...
Read more: https://www.science.org/content/article/how-did-ancient-bugs-get-so-big-prevailing-theory-may-be-wrong
