Board Thread:Questions and Answers/@comment-90.244.94.220-20141004224535

How would history have changed if the atmosphere was always a mixture of-


 * 1) 35% Helium
 * 2) 1% Hydrogen
 * 3) 0.5% Carbon dioxide
 * 4) 22.9% O2
 * 5) 1% Sulpher monoxide
 * 6) 1% Argon
 * 7) 1% Ozone (O3)
 * 8) 0.1% Neon
 * 9) 1% Water vapor
 * 10) 0.5% Sulpher dioxide
 * 11) 0.5% Chlorine
 * 12) 11% Free Oxygen (O1)
 * 13) 20% Nitrogen

More acid rain and more aquatic and subterranean animals than birds or dinasores? Calcareous shells would desolve away, but leathery cuticles would not. 