https://www.sciencedaily.com/releases/2024/01/240105145059.htm
1.75 billion year old cyanobacteria fossils have been identified with
thylakoid membranes. These are structures in the bacteria where aerobic photosynthesis occurs. The anoxygenic photosynthetic bacteria are
supposed to have evolved first, and do not seem to have thylakoid
structures. It just means that cyanobacteria evolved by at least 1.75
billion years ago. The assumption is that aerobic photosynthesis
evolved around 2.4 billion years ago when the oxygenation of the earth
began. This likely means that they still haven't found the oldest
thylakoid membranes, but we likely do not know exactly when they did
evolve. I guess they could have evolved after aerobic photosynthesis
evolved. They are the stacked structures that you see in the biology
textbooks found in eukariotic chloroplasts (endosymbiotic cyanobacteria).
Ron Okimoto
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