Evolution: stromatolites early appearance (Introduction)

by David Turell , Thursday, March 16, 2023, 19:38 (406 days ago) @ David Turell

Masses of cyanobacteria making oxygen:

https://www.discovermagazine.com/planet-earth/we-owe-our-lives-to-3-billion-year-old-st...

"Stromatolites weren’t one distinct creature, but many — they’re formed by colonies of cyanobacteria, microscopic organisms that use photosynthesis to sustain themselves. Living mostly in water, the colonies that made stromatolites were somewhat sticky, thanks to a compound they secreted, which caused sediment to build up around the cyanobacteria.

"Long before any kind of creatures walked the Earth, in a time that predates even the existence of marine or plant life, stromatolites were already here. Billions of years ago, our young planet, once too hot and its surface too molten to harbor life, had begun to cool. This allowed the first oceans to form.

"Earth was still not a hospitable place, but simple bacteria could survive and form colonies that would become stromatolites. For at least two billion years, these sticky little cyanobacteria stromatolites were the dominant life form on Earth.

"Stromatolites predate the dinosaurs by a wide margin. Not only were they once the primary form of life here, as bacteria they are also the oldest known life on Earth and are found in the oldest fossils ever discovered. Evidence of their existence stretches back as much as 3.5 billion years, to an almost unimaginably remote time known as the Archean Eon.

"Back then, Earth was nothing like it is now. Were you to visit it during Archean times, you wouldn’t last long: The atmosphere of the planet then was a mix of gasses like carbon dioxide, methane and ammonia, among others, that would have been toxic to Earth’s current inhabitants. But that wasn’t the case for stromatolites, of course. They thrived in this environment, even as they were slowly changing it.

"In fact, most of life as we know it would never have developed on earth without those tireless little cyanobacteria colonies. Thanks to the wonders of photosynthesis, stromatolites in their billions were busily absorbing sunlight, water and carbon dioxide while pumping out tiny bubbles of oxygen into the world’s oceans.

"That doesn’t sound like much of a task, but the stromatolites of early Earth kept at it long enough that, over the eons, the oceans became saturated with oxygen. Eventually, this critical gas began to be released into the atmosphere, creating an environment that would support more complex forms of life, including the dinosaurs and, eventually, us.

***

"To date, scientists know of a few locations around the world where stromatolites can still live — generally, they require very salty and sheltered water environments. One of the most famous destinations — famous among stromatolite fans, anyway — is Western Australia’s Hamelin Pool Marine Nature Reserve. Australia is also home to an even rarer form of cave-dwelling stromatolite.

"Other living stromatolites have also been found in the Bahamas and Mexico, among a few other places. The ecosystems that stromatolites require to thrive are delicate and most of these rare enclaves of living fossils are under threat."

Comment: This shows how carefully God planned evolution. He had things worked out all in order of a necessary progression. Just as the survival rate of 0.01%b was necessary.