Anonymous asked in Science & MathematicsEarth Sciences & Geology · 2 months ago

Fossils are found in layers of rocks called strata. Why do fossils change between strata?

5 Answers

  • CRR
    Lv 7
    2 months ago

    Different strata represent different ecosystems.

  • 2 months ago

    Two main reasons apply.  The first one is that life is not the same at every spot on earth at the same time, so even when the sediments formed at the same time, the type of life that is present or absent will be different from place to place. You would even see a change at the same place if the conditions changed, even if life itself never changed, but only moved around as environments changed.

    But that does lead to the second main reason. Life does not stay the same forever.  It changes with time, so even if the environment stays the same, more or less (same basic sediments), the fossils will come from different life forms and be different, if the life forms themselves have changed.

    Life is not constant, and not the same everywhere at the same time even if it was, basically.  Can't expect elephant bones in North American sediments depositing today, because there are no elephants here today.  Won't find any beavers in Australia either.  However, just because none are there today does not mean there were none there ever, and never will be in the future.  Things can change.  They will change, just a question of in what way.

  • Anonymous
    2 months ago

    The animals alive at that particular time are different.

    Perhaps you need to read about what strata are.

  • 2 months ago

    Evolution, adaptation and mutation. 

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  • Anonymous
    2 months ago

    Different strata were formed at different points in history. In other words, each strata represents a different geological timeframe. Fossils are merely mineralised organisms on account of avoiding biodegradation when they died (loads of different mechanisms). So when they died determines which strata they're in. Since these timeframes are in the order of tens to hundreds of millions of years, the change in flora and fauna can be drastic. 

    Don't copy and paste that in your test/homework. I've worded it dreadfully. Just tried to outline the concept for you if that helps, use your own words. 

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