The Great Oxygenation Event occurred about 2.3 billion years ago, around the same time as complex cells emerged. We didn't see multicellular eukaryotic life until 1.6 billion years ago, give or take. Plants certainly played and still play a hugely important role, but they probably weren't responsible for the initial change to an oxidizing atmosphere.
My book: https://impacts.to/downloads/lowres/impacts.pdf
The Great Oxygenation Event occurred about 2.3 billion years ago, around the same time as complex cells emerged. We didn't see multicellular eukaryotic life until 1.6 billion years ago, give or take. Plants certainly played and still play a hugely important role, but they probably weren't responsible for the initial change to an oxidizing atmosphere.
My sources: https://impacts.to/bibliography.pdf