What dramatic changes happened during the Precambrian?
1. Evolution of life: The Precambrian saw the emergence and evolution of the earliest forms of life on Earth. Simple single-celled organisms, such as bacteria and algae, began to populate the oceans.
2. Formation of continents: During the Precambrian, the Earth's continents were taking shape through the process of plate tectonics. Continents were forming and merging, leading to the formation of supercontinents like Rodinia.
3. Rise of oxygen levels: One of the most significant changes during the Precambrian was the rise of atmospheric oxygen levels. Early photosynthetic organisms produced oxygen as a byproduct, leading to the oxygenation of Earth's atmosphere.
4. Snowball Earth: The Precambrian also saw episodes of extreme climate change, including the "Snowball Earth" events where Earth's surface was completely or partially covered in ice.
5. Evolution of eukaryotic cells: The Precambrian saw the evolution of more complex cells known as eukaryotic cells, which have a defined nucleus and other membrane-bound organelles.
6. Mass extinctions: Although not as well-documented as the mass extinctions in the Phanerozoic Eon, the Precambrian also saw periods of mass extinction that wiped out significant portions of life on Earth.
Overall, the Precambrian was a time of significant change and evolution, laying the foundation for the diverse life forms that would eventually inhabit the planet in the following eras.