Giant dragonfly theory debunked by new research

A long-held theory explaining the absence of giant insects today, known as the 'oxygen constraint hypothesis,' has been challenged by recent scientific findings. This hypothesis suggested that lower atmospheric oxygen levels prevented insects from growing as large as their prehistoric counterparts, which included dragonflies with wingspans over two feet. Researchers investigated the tracheal system, the insect's breathing apparatus, and found that the volume of breathing tubes within flight muscles did not significantly increase with insect size. This suggests that oxygen diffusion limitations are not the primary factor restricting insect size.