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Before there were Neanderthals or Denisovans, or vaguely humanoid primates, primitive mammals, or fish that crawled out of the ocean to become the first land animals, our earliest ancestors were microorganisms. .
More complex organisms like us are descendants of eukaryotes that have a nuclear membrane around their DNA (as opposed to prokaryotes, which do not have a nuclear membrane).Eukaryotes were thought to have evolved Diversification began several billion years ago during the late Paleoproterozoic era and began to diversify by about 800 million years ago. Their diversification was not well understood. Now, a research team led by paleontologist Leigh Ann Readman of the University of California, Santa Barbara, has discovered that, despite being 1.64 billion years old, it is already diverse and has surprisingly sophisticated characteristics. Discovered microfossils of nuclear organisms.
“High levels of eukaryotic species richness and morphological differentiation occurred in the late Paleoproterozoic, but [fossils] “Although the earliest records of eukaryotes have been preserved, the eukaryotic clade has a much deeper history,” Reidman and her team said in their paper. study It was recently published in a paleontology paper.
really, really, really old trick
Eukaryotes likely evolved during the late Paleoproterozoic Era, when several major changes on Earth occurred, including a rapid increase in atmospheric oxygen and changes in ocean chemistry. This could have been between 3 billion and 2.3 billion years ago. Reidman’s team investigated layers of sedimentary rock in the Limbuniya region of Australia’s Birindudu Basin. The fossils they unearthed included a total of 26 taxa and 10 previously undescribed species. One of them is Rimbunyasphaera gill opercula, species of new genus Rimbunyasu blowjob.
what makes it so L. operculata What is very distinctive is that it has features that seem to be evidence of a survival mechanism used by modern eukaryotes. There are some microorganisms that form protective cyst They can overcome harsh situations. When the situation becomes more bearable, enzymes are produced that dissolve part of the cyst wall and form an opening or pylorus, through which it is possible to crawl out. This opening also has an operculum, or gill operculum.These were both observed L. operculata.
Division in fossilized unicellular organisms may be the result of taphonomic processes that destroy cell walls, but complex structures such as pylorus and gill operculae are not found in prokaryotes, so the species is not eukaryotic. This suggests that there must be one.
I didn’t know they could do that.
Several previously known extinct eukaryotic species have also surprised scientists with unexpectedly advanced features. Satka Fabosa Inside the cell were vesicles surrounded by a membrane with a plate-like structure. another species, Birindudutuva Brigandinia, We also saw plates around the vesicles, but none of the plates were as diverse in shape as those seen in different locations. S. Fabosa individual. These plates came in a variety of shapes and sizes, the so-called S. Fabosa Multiple species.
plated vesicles S. Fabosa This plate is a possible indicator that the Golgi apparatus was present in these organisms, leading Liedman to conclude that this species must have been eukaryotic. did. After the cell’s endoplasmic reticulum synthesizes proteins and lipids, the Golgi apparatus processes and packages those materials depending on where they go next. Liedman and her team believe that the Golgi apparatus, or Golgi-like bodies, transported substances within the cell and formed plates around the vesicles, as seen in the diagram. S. Fabosa. It is thought that the hypothetical Golgi apparatus itself did not have these plates.
This type of complex classification of cellular contents is characteristic of all modern eukaryotes. “Including taxa” Satka Fabosa… is considered [eukaryotes] “This is because they have a complex plate-like vesicular structure,” the researchers wrote in their paper. study. These new fossils suggest that it occurred fairly early in their history.
It is clear that eukaryotes have been around for hundreds of millions of years longer than we thought, and are much more complex and diverse than we thought. Older samples may also exist. Although we don’t have any fossil evidence close to the origins of eukaryotes, samples from more than a billion years ago, such as those discovered by Liedman and her team, suggest that eukaryotes evolved and, by extension, we tells us more than ever before about the evolution of
Paleontology Papers, 2023. DOI: 10.1002/spp2.1538
