Rowan C. Martindale, Sinjini Sinha, Travis N. Stone et al
Found at depths of 180 meters, the fossils indicate that microbial communities existed in much deeper marine environments than expected.
Newly discovered fossil imprints of ancient microbial colonies suggest scientists may need to rethink where we look for the first evidence of life on Earth.
The fossils found in mountains of the Central High Atlasin Morocco, indicate that microbial communities thrived in deeper and more unstable marine environments than previously believed, says .
The fossil structures, described as wrinkled, wavy patterns, were preserved in turbidites, which are sedimentary layers formed by submarine landslides. AND
This discovery surprised researchers, as these microbial mats are typically found in shallow waters, where sunlight supports the bacteria.
Moroccan turbidites, however, were deposited approximately 180 million years ago depths of at least 180 meterswhere the light would be minimal.
“These wrinkled structures shouldn’t be in this environment of deep waters,” said Rowan Martindalegeobiologist at the University of Texas at Austin and lead author of , published in the journal Geology.
Martindale discovered the fossils while studying ancient reef systems in Morocco’s Dadès Valley. While walking on fine sandstone and siltstone, he noticed unusual wrinkled textures that resembled fossilized microbial mats.
These delicate structures are rarely preserved in rocks less than 540 million years old, since increased animal activity over time tends to destroy them.
Further analysis showed that the Moroccan fossils could not have been formed by photosynthetic microbes due to the lack of light at such depths. However, chemical tests revealed high carbon levels in rock layers, indicating a biological origin.
The researchers concluded that the organisms were likely chemosynthetic, obtaining energy from chemical reactions involving compounds such as sulfur rather than sunlight.
The study suggests that submarine landslides may have played a key role in maintaining these microbial communities.
As debris flows transported material from the continental shelf to deeper waters, transported organic matter which decomposed into methane or hydrogen sulfide, which served as ideal energy sources for chemosynthetic microbes.
The findings suggest that scientists looking for ancient life should expand their focus beyond shallow-water formations, including rocks formed in deeper marine environments.
According to Martindale, wrinkled structures are “really important pieces of evidence in the early evolution of life.”
