[garybob]

Science is knowing that the first phytoplanktons that actually created oxygen led to the largest die-off in the history of the planet as they pumped their lethal, toxic, noxious waste into the atmosphere. The creatures that were left were adapted to use oxygen. Over time, the phytoplanktons became plants, the remaining organisms founded the animal kingdom.

Since no one was around to observe this event, it is merely conjecture, a theory if you will. Unless you have hard evidence to the contrary? And assertions, however stridently and loudly proclaimed, do not pass as "hard evidence".

[jnaujok]

No, I have no hard evidence, since your measure is "were you there."

I have only the incredibly circumstantial evidence of massive fossil records, ice cores, radio isotope dating, the fact that Oxygen would vanish in a few million years without a constant source of it on the planet, massive evidence of anaerobic bacteria and life forms before this event, and the complete absence of them afterwards, the arrival of whole new forms of life that used photosynthesis rather than metal-acid reactions as energy sources, and then another set that suddenly use redox reactions for the first time in the fossil record, thousands of scientific papers, thousands of books, millions of established scientific facts and researchers agreeing, the fact that Oxygen in inorganic chemistry is a corrosive, quickly absorbed gas that almost never, ever occurs in its elemental form in nature.

But no, no hard evidence.