Anonymous ID: 658b76 Feb. 3, 2024, 2:36 p.m. No.20352420   ๐Ÿ—„๏ธ.is ๐Ÿ”—kun

efore Neanderthals and Denisovans, before vaguely humanoid primates, proto-mammals, or fish that crawled out of the ocean to become the first terrestrial animals, our earliest ancestors were microbes.

 

More complex organisms like ourselves descend from eukaryotes, which have a nuclear membrane around their DNA (as opposed to prokaryotes, which donโ€™t). Eukaryotes were thought to have evolved a few billion years ago, during the late Palaeoproterozoic period, and started diversifying by around 800 million years ago. Their diversification was not well understood. Now, a team of researchers led by UC Santa Barbara paleontologist Leigh Ann Riedman discovered eukaryote microfossils that are 1.64 billion years old, yet had already diversified and had surprisingly sophisticated features.

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What makes L. operculata so distinct is that it has a feature that appears to be evidence of a survival mechanism used by modern eukaryotes. There are some extant microbes that form a protective cyst so they can make it through harsh conditions. When things are more tolerable, they produce an enzyme that dissolves a part of the cyst wall into an opening, or pylome, that makes it possible for them to creep out. This opening also has a lid, or operculum. These were both observed in L. operculata.

 

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https://arstechnica.com/science/2024/02/our-oldest-microbial-ancestors-were-way-ahead-of-their-time/