Oxygen only one part and for all we know there were other trace gasses in the air they required that we don't even know about. There are all kinds of animals t

Oxygen only one part and for all we know there were other trace gasses in the air they required that we don't even know about. There are all kinds of animals today we cannot keep alive in captivity because they require some sort of unknown sequence of environmental triggers to activate or deactivate various processes in their body. For instance cheetahs are nearly impossible to breed in captivity because their mating process requires running for many miles to exhaustion. Without this the pregnancy rate is in the abyss even with artificial methods. There are endless examples thats just one off the top of my head.