- The Precambrian era began roughly 4.6 billion years ago with the formation of Earth.
- The earth's atmosphere and oceans were formed when the planet cooled and degassed.
Formation of Supercontinents:
- The Precambrian was marked by the formation and breakup of supercontinents. One of the earliest known continents, Vaalbara, is from around 3.6 billion years ago.
- Other supercontinents that existed during the Precambrian include Columbia and Rodinia.
Evolution of Life:
- The Precambrian era witnessed major events in the evolution of life on Earth.
- Prokaryotic organisms, such as cyanobacteria, emerged around 3.5 billion years ago and started releasing oxygen through photosynthesis.
- Eventually, around 2.1 billion years ago, the Great Oxygenation Event (GOE) occurred, significantly increasing atmospheric oxygen levels.
- Eukaryotic cells, more complex organisms, appeared around 2 billion years ago.
Formation of Stromatolites:
- Stromatolites, structures created by the buildup of cyanobacterial mats, appeared during the Precambrian.
- These structures provide insights into the ancient microbial life and the conditions of the early Earth's environment.
Origin of Photosynthesis:
- Photosynthesis, the process by which plants and some microorganisms harness energy from sunlight, originated during the Precambrian.
- The presence of photosynthesizing organisms is believed to have greatly influenced the composition of Earth's atmosphere.
Evolution of Multicellular Organisms:
- Towards the end of the Precambrian era, around 650 million years ago, multicellular organisms began to appear.
- These early organisms were simple, such as sponges, and lacked tissues and organs.
These events during the Precambrian era set the stage for the complex life forms and ecosystems that developed during subsequent geological eras, such as the Paleozoic and Mesozoic eras.
