Theoretical origin of life: early complex fossils (Introduction)

by David Turell , Wednesday, July 31, 2024, 17:56 (115 days ago) @ David Turell

2.1 billion years ago:

https://www.sciencealert.com/complex-life-on-earth-may-be-1-5-billion-years-older-than-...

"An unusually substantial number of fossils large enough to be seen without a microscope have been discovered in the Franceville Basin, and it's not clear what we're to make of them. Earlier studies have also suggested these macrofossils point to the first complex life on the planet.

"Here, the researchers link the nutrient enrichment of the water to the collision of two ancient continents, which then created a shallow inland sea and the conditions for cyanobacterial photosynthesis, a chemical process that would've led to an underwater environment more conducive to biological complexity.

"This would have created a natural laboratory for organism diversity and evolutionary leaps in size and structure, the researchers contend. However, because the body of water was isolated, these more sophisticated forms of life wouldn't have spread elsewhere or survived to the next jump forward.

***

"These findings may point to complex life on Earth evolving in two steps: once following the first major atmospheric oxygen rise 2.1 billion years ago, and again following a second rise 1.5 billion years later.

"In fact, complex life might have arisen several times over the millennia, as has been suggested by other studies. Scientists are still working to pin down which types of life evolved when, and there's no guarantee that all evolutionary jumps would've stuck.

"Delving this far back into the past isn't easy, of course; it involves some careful analysis of ancient fossils and environments that may have harbored conditions suitable for what these researchers describe as "macrobiological experimentation'".

Comment: Earliest life is still 3.5 billon years ago in stromatolites. But more complex life led into the Ediacaran period with these newer fossils connecting the time frame.