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Oldest Animal Fossils Found in Lakes, Not Oceans

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  • Oldest Animal Fossils Found in Lakes, Not Oceans

    Oldest Animal Fossils Found in Lakes, Not Oceans

    Conventional wisdom has it that the first animals evolved in the ocean.

    Now researchers studying ancient rock samples in South China have found that the first animal fossils are preserved in ancient lake deposits, not in marine sediments as commonly assumed.

    These new findings not only raise questions as to where the earliest animals were living, but what factors drove animals to evolve in the first place.

    For some 3 billion years, single-celled life forms such as bacteria dominated the planet. Then, roughly 600 million years ago, the first multi-cellular animals appeared on the scene, diversifying rapidly.

    The oldest known animal fossils in the world are preserved in South China's Doushantuo Formation. These fossil beds have no adult specimens - instead, many of the fossils appear to be microscopic embryos.

    "Our first unusual finding in this region was the abundance of a clay mineral called smectite," said researcher Tom Bristow, now at the California Institute of Technology in Pasadena. "In rocks of this age, smectite is normally transformed into other types of clay. The smectite in these South China rocks, however, underwent no such transformation and have a special chemistry that, for the smectite to form, requires specific conditions in the water - conditions commonly found in salty, alkaline lakes."

    The researchers collected hundreds of rock samples from several locations in South China. All their analyses suggest these rocks were not marine sediments.

    "Moreover, we found smectite in only some locations in South China, and not uniformly as one would expect for marine deposits," Bristow said. "Taken together, several lines of evidence indicated to us that these early animals lived in a lake environment."

    This discovery raises questions as to how and why animals appeared when they did.

    "It is most unexpected that these first fossils do not come from marine sediments," said researcher Martin Kennedy, a geologist at the University of California at Riverside.

    "Lakes are typically short-lived features on the Earth's surface, and they are not nearly as consistent environments as oceans are," he explained. "So it's surprising that the first evidence of animals we find is associated with lakes, which are far more variable environments than the ocean. You'd expect the first appearance of animals to be in the most conservative, stable environments we could imagine."

    It remains possible, Kennedy noted, that animal fossils of similar or older age exist that remain to be found that are marine in origin. However, at the very least, this work suggests "that animals had already taken on the ability to deal with the environmental fluctuations one sees in lake environments," he said. "That suggests that their evolutionary response is much more rapid that I would have supposed, and that the earliest animals were far more diverse than imagined."

    If animals did first develop in lakes, one aspect of lake environments that could have spurred on their evolution is how much easier it is for air to percolate through them, given how much shallower they typically are than the ocean.

    "The most popular explanation for the evolution of animals has to do with the increase in oxygen in Earth's atmosphere at that time," Kennedy told LiveScience. "It's possible that lakes were the first to benefit from that increase in oxygen."

    The scientists detailed their findings online July 27 in the Proceedings of the National Academy of Sciences.

    http://news.yahoo.com/s/livescience/...lakesnotoceans
    THE ROAD TO FREEDOM AND JUSTICE IS A LONG ONE!

  • #2
    Re: Oldest Animal Fossils Found in Lakes, Not Oceans

    The oxigen permeation into smaller bodies of water makes sense and it is easy to see how this could help animal life to develope. It is important to keep in mind though that the first animals were invertibrates (had no bones) so their presence in the fossile records is minimal and so is our understanding of the first forms of animal life. It is hard to speculate on the exact origins of animal life when it's origins leave few clues. Sako you are finaly starting to post interesting stuff, i hope you continue to do so.
    Hayastan or Bust.

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    • #3
      Re: Oldest Animal Fossils Found in Lakes, Not Oceans

      How far was the moon away from the earth 3 billion years ago?
      "Nobody can give you freedom. Nobody can give you equality or justice or anything. If you're a man, you take it." ~Malcolm X

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      • #4
        Re: Oldest Animal Fossils Found in Lakes, Not Oceans

        Sako you are finaly starting to post interesting stuff, i hope you continue to do so.
        I've always posted interesting stuff. You've simply perceived it in the wrong way.
        THE ROAD TO FREEDOM AND JUSTICE IS A LONG ONE!

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        • #5
          Re: Oldest Animal Fossils Found in Lakes, Not Oceans

          Originally posted by KanadaHye View Post
          How far was the moon away from the earth 3 billion years ago?
          It was much closer then it is today. The lunar cycle played a much more significant role back than. Hi tide was many times higher then it is today and everything living in water evolved around lunar cycles (much more so then now). The moon has been steadily moving further away from earth pretty much since it was created by what astronomers think was a huge collision on earth with another big mass. The moon is the part of the mass that colided with the earth and eventhough it didnt meld in with the planet (atleast what we see of it today) it did stay within its gravatational influence but has been moving away from it steadily since then.
          Hayastan or Bust.

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          • #6
            Re: Oldest Animal Fossils Found in Lakes, Not Oceans

            Originally posted by Sako View Post
            I've always posted interesting stuff. You've simply perceived it in the wrong way.
            Nah the other stuff was not interesting - not for me anyways.
            Hayastan or Bust.

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            • #7
              Re: Oldest Animal Fossils Found in Lakes, Not Oceans

              Originally posted by Haykakan View Post
              It was much closer then it is today. The lunar cycle played a much more significant role back than. Hi tide was many times higher then it is today and everything living in water evolved around lunar cycles (much more so then now). The moon has been steadily moving further away from earth pretty much since it was created by what astronomers think was a huge collision on earth with another big mass. The moon is the part of the mass that colided with the earth and eventhough it didnt meld in with the planet (atleast what we see of it today) it did stay within its gravatational influence but has been moving away from it steadily since then.
              So a solar eclipse would have blocked the sun for a significant amount of time. Right now the moon is exactly the right distance away to just fully block the sun during a total eclipse. I guess you could say we're living in an almost perfect period of time.
              "Nobody can give you freedom. Nobody can give you equality or justice or anything. If you're a man, you take it." ~Malcolm X

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              • #8
                Re: Oldest Animal Fossils Found in Lakes, Not Oceans

                Nah the other stuff was not interesting - not for me anyways.
                I respect that. Thanks for being honest. But you didn't have to go around dissing if you didn't like something. All the same, moving on.
                THE ROAD TO FREEDOM AND JUSTICE IS A LONG ONE!

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                • #9
                  Re: Oldest Animal Fossils Found in Lakes, Not Oceans

                  Originally posted by KanadaHye View Post
                  So a solar eclipse would have blocked the sun for a significant amount of time. Right now the moon is exactly the right distance away to just fully block the sun during a total eclipse. I guess you could say we're living in an almost perfect period of time.
                  The living in perfect period of time kinda makes me giggle but yeh the eclipse was different back then and a full moon would have been HUGE and in your face compared to what it is today.
                  Hayastan or Bust.

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