How did Earth and atmosphere change during Precambrian time?

During the Precambrian time, Earth's atmosphere was mostly composed of carbon dioxide, methane, ammonia, and water vapor. Over time, as cyanobacteria evolved and photosynthesis increased, oxygen began to accumulate in the atmosphere, leading to the Great Oxidation Event around 2.4 billion years ago. This rise in oxygen levels was a major shift that had profound effects on the evolution of life on Earth.