Complex Animals Led to More Oxygen, Says Maverick Theory
quantamagazine.org
quantamagazine.org
For example, there's less need to hide in the depths from predators if the predators are wimpy, and predators without enough oxygen will stay wimpy. The diving energy expenditure is not worth it under wimpy predation. Capability to dive deep enough and the predator/pray competition both had to reach a level to trigger the feedback cycle. Earlier generations couldn't get either the depth nor be potent enough predators because they were too primitive.
Or do they mean that the rate needs to be diffusion higher than at what the animals are consuming it? That's a interesting question. Do animals actually make a dent in the ocean's oxygen content? If their rate of consumption is small enough it probably doesn't matter too much.
ex: Microbe A diffuses (0.0003mg of oxygen per day)x(population of species)x(years) = 100 billion tons of oxygen diffused into atmosphere per millenia
Here's another study from 2014 that talks about the link between animals and oxygenation of the oceans. (This paper just focused on the mixing of oxygen in the ocean, it doesn't claim that more ocean-oxygen led to a higher oxygen world like the OP. https://www.sciencedaily.com/releases/2014/03/140309150540.h... )
Around 40 million years ago when grasses started to take over there was a big resultant change of what went on in the ocean, more nutrients, i.e. fixed nitrogen. This was former 'soil' blown off continents that had gone through a bit of climate change. River sediment too.
What happened at the big bang for life 500 million years ago to resolve the nitrogen problem is beyond my wikipedia skills.
Also what was the original atmosphere made of, before the oxygen takeover?
What I think is amazing is that every rusted or oxidised thing had to get its oxygen from somewhere, i.e. the waste product from micro-organisms getting their carbon. The atmosphere only came about when everything that could be oxidised was oxidised.