Live Science reported that a 3.5-billion-year-old fossil microbial community has been found in Australia by scientists, revealing some of the most ancient fossil life forms ever discovered.
The new find reveals that a scant 1 billion years after Earth’s origin, complex microbial communities that clung to sediments along the windswept seashore had already begun harvesting energy from sunlight, rather than the rocks.
…A few stromatolites, or domelike like rock structures built by ancient microbial communities, have been found at the Strelley Pool formation in Australia that may date to about 3.45 billion years ago. Fossil sulfur-eating microbes from about 3.4 billion years ago have also been found there as well. Other fossils from South Africa reveal microbial communities that date to 2.9 billion years ago.
…More primitive rock-eating bacteria, called chemolithotrophs, likely evolved before the microbial mats, though no trace of Earth’s earliest pioneers has yet been found. Chemolithotrophs harvest energy by chemically modifying minerals such as iron or sulfur in the rock, and many such bacteria are still alive today.
But the newly discovered communities were anchored to the seashore close to sun and water, so they probably weren’t eating minerals found in rock. Instead, they must have harvested energy through photosynthesis, suggesting such bacteria evolved earlier than previously thought.