Well, trying to struggle through your only semi-coherent question, and guessing at what you mean --
Unless the chemical composition, electrical potential, radiation intake, and heat dynamic on a planet is just so, life can't get started.
And HOW that life operates depends on those factors too. The dinosaurs were ABLE to be huge with such inefficient breathing and circulatory systems because the oxygen percentage of the air was higher than it is now.
Going further back, there was a time when free oxygen was rare and life didn't even USE oxygen -- anaerobic microorganisms are a relic of that time (like Tetanus, for instance).