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Thread: Cambrian Era Life

  1. #1 Cambrian Era Life 
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    Was the first evidence of eukaryotes the Ediacara biota? What exactly were Aspidella terranovica (it's been suggested that it was a primative jellyfish...) and Dickinsonia costata?


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  3. #2  
    Forum Cosmic Wizard i_feel_tiredsleepy's Avatar
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    I don't think it's the earliest evidence of eukaryotes, but the earliest evidence of megakaryotes.


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    Forum Junior DrmDoc's Avatar
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    Perhaps a type of photoautotroph as suggested by precambrian carbon deposits.
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  5. #4 Re: Cambrian Era Life 
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    Quote Originally Posted by gottspieler
    Was the first evidence of eukaryotes the Ediacara biota? What exactly were Aspidella terranovica (it's been suggested that it was a primative jellyfish...) and Dickinsonia costata?
    Ediacaran fauna are generally considered to be the first macroscopic eukaryotes as already mentioned. They appear ~575 Ma after the Gaskiers glaciation (~580 Ma). However, I recently read a paper suggesting there is possible animal microfossils as early at ~600 Ma. As it is, molecular clock dating puts the origin of the eukaryotic cell at least as far back as 1.2 Ga... though that method is somewhat controversial.

    As for the animals themselves... that's a toughie. I think the tentative consensus is that stem-group cnidarians are present. The point to take away from this is that jellyfish are crown-group cnidarians, but stem-group cnidarians are not jellyfish (though they may have been jellyfish-like).
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    WYSIWYG Moderator marnixR's Avatar
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    biomarkers of sponges have been found in rocks aged 635 MYA : Ancient sponges leave their mark
    "Reality is that which, when you stop believing in it, doesn't go away." (Philip K. Dick)
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    Quote Originally Posted by marnixR
    biomarkers of sponges have been found in rocks aged 635 MYA : Ancient sponges leave their mark
    Wow, that is outstanding!
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  8. #7  
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    Quote Originally Posted by marnixR
    biomarkers of sponges have been found in rocks aged 635 MYA : Ancient sponges leave their mark
    IIRC they were some sort of steroid...

    There is a debate now about whether is true demospongia or if this is an ancestor of the group.



    New related links:

    http://news.nationalgeographic.com/n...e-picture.html

    (anomalocarid outside the cambrian!!!!???)



    okay, so all those precambrian 'worm tracks'? Yeah...maybe not worms at all.

    http://news.bbc.co.uk/2/hi/science/nature/7739703.stm


    Speaking of the cambrian, I have done work at the burgess shale!!
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    WYSIWYG Moderator marnixR's Avatar
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    Quote Originally Posted by mormoopid
    Speaking of the cambrian, I have done work at the burgess shale!!
    can't be cambrian, it's not even in Wales :wink:
    "Reality is that which, when you stop believing in it, doesn't go away." (Philip K. Dick)
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  10. #9  
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    haha, your English namings have leeched their way through geology long enough!

    Sadly, when I was there, I didn't see any anomalocaris (I mean the Burgess)
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  11. #10  
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    Hello All,

    Here's a recent article on the controverial period of life's emergence on our blue speck:

    http://www.sciencedaily.com/releases...0216131450.htm
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  12. #11 thanks 
    Forum Sophomore hokie's Avatar
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    Thanks that was a good article
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  13. #12  
    Forum Cosmic Wizard spuriousmonkey's Avatar
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    That was a shit article.

    "Controversy Over World’s Oldest Traces Of Life"

    Turns out there isn't really controversy at all. Most solid arguments point out that it most likely isn't the oldest trace of life.

    If most evidence points in one direction there cannot be a controversy. If one group sticks to the original research that has been discredited it is called: lone dissenter.
    "Kill them all and let God sort them out."

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  14. #13  
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    Quote Originally Posted by spuriousmonkey

    If most evidence points in one direction there cannot be a controversy. If one group sticks to the original research that has been discredited it is called: lone dissenter.
    post in pseudoscience more, please.
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  15. #14  
    Forum Cosmic Wizard spuriousmonkey's Avatar
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    If they rename pseudoscience to seance.
    "Kill them all and let God sort them out."

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    Forum Professor Zwirko's Avatar
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    By the Middle Cambrian its thought that there were already representative members of the modern classes of Cnidaria (hydrozoans, scyphozoans, and cubozoans). Here's a rather pretty fossil with interpretive drawing:





    Image from a PLoS ONE paper: "Exceptionally Preserved Jellyfishes from the Middle Cambrian"
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  17. #16  
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    The reason it's called "controversy" is because it's the modern buzzword for "Please read this!" and "We're neutral!". By claiming something is biased or has controversy they put up a shrowd of false neutrality when there is no neutrality whatsoever. To accept that one view is certain would anger a portion of their reader base and lead to less money. Why do that when you can represent all views with some choice buzzwords?

    Indeed, if wikipedia has a flaw, this is the most severe. "NPV! NPV!" is the battle cry that has destroyed the most powerful of nations from within. We have raised a generation of emotional hippies that believe all viewpoints are equal. HLORF.
    Om mani padme hum

    "In dishonorable things we are not bound to obey any man." - The Book of the Courtier [1561], pg 99 (144 in pdf)
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