Lost in Time: Exploring a Submerged Lagoon Network Housing Ancient Living Fossils Resembling Organisms from Over 3 Billion Years Ago
Unveiling Argentina's hidden lagoon network reveals remarkable living fossils resembling those from over 3 billion years ago, offering an unprecedented glimpse into Earth's early life and potentially shedding light on ancient Mars
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New research has revealed a previously undiscovered ecosystem in the expansive system of lagoons in the salt plains of Puna de Atacama, an arid plateau in Argentina. Scientists have found giant stromatolites that offer a window into the earliest life on Earth and potential insight into life on Mars.
Stromatolites, layered rocks formed by the growth of blue-green algae, or cyanobacteria, through photosynthesis, are considered one of the oldest ecosystems on Earth. According to NASA, they represent the earliest fossil evidence for life on our planet, dating back at least 3½ billion years ago.
"These are certainly similar to some of the earliest macrofossils on our planet, and exist in a rare type of environment on modern Earth," stated Brian Hynek, a professor in the department of geological sciences at the University of Colorado Boulder, who contributed to the documentation of the ecosystem. "They provide a window into the distant past, giving us an idea of what life might have looked like 3½ billion years ago on our planet."
During Earth's Precambrian era, giant stromatolites were abundant, but now they are only found in a few areas around the world, such as the Bahamas and the Shark Bay in Western Australia. Modern stromatolites are much smaller than their ancient counterparts, which used to reach heights of up to 20 feet and widths of 16 to 22 feet. Recently discovered stromatolites in the Puna de Atacamas lagoons are up to 15 feet wide and several feet high, as reported by the University of Colorado Boulder.
The newly discovered giant stromatolites in Puna de Atacama are mostly composed of the minerals gypsum and rock salt.
Brian Hynek mentioned that while stromatolites typically thrive in alkaline environments, the lagoons in the Puna de Atacama system are actually acidic. He also noted that although the stromatolites found today are primarily made of limestone, the structures themselves are mainly composed of gypsum and halite (rock salt).
The reason for the large size of the stromatolites remains unclear, according to Hynek. He suggested that the undisturbed inland ecosystem may have allowed them to grow without any obstacles for an extended period.
Unlike their modern counterparts, ancient stromatolites thrived in an oxygen-deprived atmosphere. In such conditions, the stromatolite microbes relied on anoxygenic photosynthesis, a process that does not require oxygen, to transform light energy into compounds essential for sustaining living cells.
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Pieter Visscher, a marine sciences professor at the University of Connecticut who has extensively studied stromatolites, expressed amazement at finding structures that could be biogenic at such a high altitude. In an email, he noted that one major issue is that the stromatolites were formed in the presence of oxygen, which did not exist until 2.3 billion years ago.
According to Hynek, the layers deeper in the rock have limited access to oxygen and are likely formed by microbes using anoxygenic photosynthesis, similar to structures found on ancient Earth.
The system of lagoons in Argentina was initially discovered through satellite imagery in April 2022.
In April 2022, while studying a lagoon with small stromatolites and microbes using anoxygenic photosynthesis in northwestern Argentina, Brian Hynek discovered a system of lagoons through satellite imagery.
"We are uncertain whether the microbes are actively contributing to the growth of the newly discovered stromatolites. Our initial observations lead us to believe they are involved, but we have yet to conduct experiments to confirm this," explained Hynek, who worked alongside microbiologist Maria Farías, the co-founder of Punabio SA Environmental Consulting, to document their preliminary findings. "There is a substantial amount of research that still needs to be conducted. We have only recently uncovered them and have barely begun to explore their potential."
According to a news release, Hynek and Farías were scheduled to present their findings on December 11 at the 2023 meeting of the Geophysical Union in San Francisco.
Potential glimpse into ancient Mars
If the stromatolites are created by microorganisms utilizing anoxygenic photosynthesis, this finding could offer valuable insight into the potential for life on ancient Mars, according to Hynek.
"We have discovered over 600 ancient lakes on Mars, with the possibility of there being an ocean as well. This suggests that Mars was much more similar to Earth in its early stages," he stated. Hynek added that minerals such as gypsum and halite, present in the stromatolites in Argentina, are also found in salt deposits across Mars.
The planet Mars
NASA
Colonizing Mars comes with significant risks and a hefty price tag, but Elon Musk is determined to pursue it. "If Mars ever supported photosynthesis and evolved life, stromatolites would be a key indicator, and that's what we're searching for," explained Hynek, a research associate at the University of Colorado Boulder's Laboratory for Atmospheric and Space Physics.
This is our best estimation of the type of fossils we might find on Mars, as they are the oldest ones found in the Earth's rock record," said Hynek. He expressed his hope to return to the lagoon soon to conduct further research on the stromatolites.
"Stromatolites on Mars? A long shot, but who knows. So far, no carbonates at the surface of Mars, but the search continues," Visscher said, for potential signs of life.Â
