What became the dominant life forms on the planet as the oxygen became more abundant?

This new life came in the form of cyanobacteria, sometimes called blue-green algae. Cyanobacteria are photosynthetic. They convert sunlight into energy and produce oxygen as a waste product. Back then, the Earth's atmosphere didn't have free oxygen in it as it does today.

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your body is trying to warm itself up. or more precisely, sensors in your skin send messages to your brain to generate heat to your body.