Basically, earth’s atmosphere was devoid of oxygen from its beginning, and it took billions of years to change that. it wasn’t until life had learned about photosynthesis before large amounts of oxygen started to accumulate in the atmosphere.
however, oxygen is a necessary prerequisite for most animal/fungus consumers, as they use oxygen to break down the organic materials. that is probably when major fossil fuel production stopped.
don’t forget the role that the Great Oxidation Event played in this.
Basically, earth’s atmosphere was devoid of oxygen from its beginning, and it took billions of years to change that. it wasn’t until life had learned about photosynthesis before large amounts of oxygen started to accumulate in the atmosphere.
however, oxygen is a necessary prerequisite for most animal/fungus consumers, as they use oxygen to break down the organic materials. that is probably when major fossil fuel production stopped.