Respiratory biology: they would be giants.
A recent study has shown that respiratory structures are disproportionately oversized in larger insects, and that oxygen supply to leg muscles may be physically constrained in the largest modern insects. High oxygen concentrations during the Carboniferous may have alleviated these physical constraints allowing the evolution of gigantic arthropods.
Lighton
John R B
JR
School of Life Sciences, University of Nevada at Las Vegas, 4505 Maryland Parkway, Las Vegas, Nevada 89154-4004, USA. Jrlighton@aol.com
D000818:Animals; D005075:Biological Evolution; D049628:Body Size / Q000502:physiology*; D007313:Insecta / Q000033:anatomy & histology* / Q000502:physiology*; D010100:Oxygen / Q000502:physiology; D012143:Respiratory Physiological Phenomena
D010100:Oxygen