Overview
- The new Nature paper, published Wednesday, reports that oxygen delivery inside flight muscle did not cap how large flying insects could grow.
- Using electron microscopes on 44 living species, the team found that tracheoles, the tiny air tubes that feed muscle cells, occupied about 1% or less of flight muscle volume across sizes.
- Exceptionally preserved fossils of the giant griffinfly Meganeuropsis showed a similar ~1% tracheole share despite an estimated mass near 100 grams, indicating ample room to add more air tubes if needed.
- The authors argue this weakens the classic oxygen-ceiling idea and suggest researchers probe alternatives such as new aerial predators like birds and pterosaurs or limits set by the exoskeleton, while other scientists note oxygen could still constrain size in airway parts upstream of the muscle.
- For decades, reconstructions of high Carboniferous oxygen and a 1995 Nature paper linked those conditions to insect gigantism, a view this study now challenges with direct measurements.