re Life at its basics
"I would guess that over 99% (mass) of Terrestrial organisms use oxygen as part of their energy transfer mechanism. "
No, by mass, and including the bacteria in the deep rocks, close to 70% of the weight (mass) of life is bacterial. and much more than half of the bacterial life is anerobic, which means that oxygen is a toxin for them. True, they are out of sight, but still, big things are so vastly outnumbered by little things that most of the mass of life is in the very little things.
As one Biologist put it, "We are not really living in the Age of Mammals, We are now and have always been living in the age of bacteria."
