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Thread: Gradualism Versus Catastrophism

  1. #1 Gradualism Versus Catastrophism 
    Forum Freshman Shubee's Avatar
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    Apparently, it's not obvious from the fossil record how to decide between the simplest of concepts, such as gradualism versus catastrophism. In your opinion, is it even possible to reasonably estimate the percentage of creatures that became fossils through an ordinary gradualistic process as opposed to catastrophes, such as megafloods, which could bury creatures in oxygen deprived silt thereby enabling the process of fossilization?

    Is the controversy resolvable? What, if anything, can be inferred from the fossil record to weigh the relative contributions of catastrophes versus gradualistic processes in the creation of all known fossils?


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  3. #2  
    Universal Mind John Galt's Avatar
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    There isn't really much of a controversy. What makes you think there is?


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    Forum Freshman Shubee's Avatar
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    Scientists believe in megafloods and in fantastic catastrophes.

    Professor Wikipedia states, "Estimates of the number of major mass extinctions in the last 540 million years range from as few as five to more than twenty."

    I asked for an interpretation of the known fossil record. What is the most reasonable estimate of the percentage of creatures that became fossils through an ordinary gradualistic process as opposed to catastrophes, such as megafloods, which could bury a large number of creatures at one time in oxygen deprived silt thereby enabling the process of fossilization?
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  5. #4  
    Universal Mind John Galt's Avatar
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    99.99% if we are looking at the true catastrophic events.

    Where do you draw the line? A very much higher percentage of 'gradualistic' preservation is the result of local 'catastrophe', not in the sense of a megaflood, just a local flood, or the landslip of a twetny foot section of cliff,.etc


    Edited for typos.
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    Forum Freshman Shubee's Avatar
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    I asked, What can be legitimately inferred from the fossil record itself? I believe you're missing my point. It's seems that you're just projecting your own imagination onto the past. That's OK. Please permit me to rephrase my question. From what we actually know about the fossil record, what are the measured average fossil densities as we move through the successive stratigraphic levels and how do they compare to the high percentages of species lost through the major extinction events listed at http://en.wikipedia.org/wiki/Extinction_event?
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  7. #6  
    Universal Mind John Galt's Avatar
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    Please define fossil density.
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    Time Lord Paleoichneum's Avatar
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    The problem with your question is that it doesn't actually make any sense.


    I will be blunt. What is the answer you are looking to get from this question??
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  9. #8  
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    Quote Originally Posted by Shubee
    I asked, What can be legitimately inferred from the fossil record itself? I believe you're missing my point. It's seems that you're just projecting your own imagination onto the past. That's OK. Please permit me to rephrase my question. From what we actually know about the fossil record, what are the measured average fossil densities as we move through the successive stratigraphic levels and how do they compare to the high percentages of species lost through the major extinction events listed at http://en.wikipedia.org/wiki/Extinction_event?
    Your first problem, before you can even start to tackle the question, is hammering out the taphonomy for each known fossil locality.

    Your second problem is assuming that catastrophic events in the biosphere correlate to catastrophism in the geosphere, which is not necessarily the case.

    Your third problem is assuming that taphonomy changes between gradualism and catastrophism, which is also not necessarily the case.

    These problems are likely resolvable; however, I can't comment on how successful paleontologists have been on this issue.
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  10. #9  
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    Quote Originally Posted by Shubee
    Scientists believe in megafloods and in fantastic catastrophes.

    Professor Wikipedia states, "Estimates of the number of major mass extinctions in the last 540 million years range from as few as five to more than twenty."

    I asked for an interpretation of the known fossil record. What is the most reasonable estimate of the percentage of creatures that became fossils through an ordinary gradualistic process as opposed to catastrophes, such as megafloods, which could bury a large number of creatures at one time in oxygen deprived silt thereby enabling the process of fossilization?
    It was my understanding that extinction events occur every 26 million years.
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  11. #10  
    Universal Mind John Galt's Avatar
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    Quote Originally Posted by granpa
    It was my understanding that extinction events occur every 26 million years.
    This is a highly questionable assertion.

    Raup and Sepkoski proposed it in 1984 on the back of the then new notion of an impact causing the KT extinction event. They claimed a 26 million year periodicity in extinction events. (Raup, D.M. and Sepkoski, J. J, Jr. Feb. 1984 "Periodicity of extinctions in the geologic past.". PNAS 81 (3): 801805. http://www.pnas.org/content/81/3/801.full.pdf ) This periodicity was attributed to a dark stellar companion to the sun on a highly eccentric orbit. One reason for the hypothesis to fail to gain traction was the failure to identify this companion, named Nemesis. However, the alleged peridocity in extinctions was not clear cut and failed to convince many researchers.

    Other researchers have identified other periods: sixteen million and thirty to forty million spring to mind. I believe a recent paper revisited the twenty six million interval. The data are not yet refined enough to rule out the possibility, but they certainly do not rule it in.
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  12. #11  
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    I dont wish to argue the point.

    for reference here are the most recent extinction events:
    145.5 Ma
    117 Ma
    91.5 Ma
    65 Ma
    33.9 (or 37.5)? Ma
    14.5 Ma


    the differences are:
    28.5
    25.5
    26.5
    31.1 (or 27.5?)
    19.4 (or 23?)

    http://en.wikipedia.org/wiki/Extinction_event
    http://www.annualreviews.org/doi/abs...rnalCode=earth
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  13. #12  
    Universal Mind John Galt's Avatar
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    How have those extinction events been defined? What time range do they extend over? How pronounced is the extinction rate above the background level? Can this peridocity be discerned for earlier epochs? Without substantive answers to these questions and similar ones your data are just a bunch of numbers.

    The consensus view remains that no clearly defined peridocity exists. It is a valid and valuable avenue of research to continue investigation of possible cycles in extinction events, but a blanket statement that extinctions occur on an approximately 26 million year cycle is at best premature and at worst simply wrong.

    You say you do not wish to argue the point, then present your numbers, thus arguing the point. I believe this is known in psycho-speak as 'passive aggressive' behaviour. This is a discussion forum: either debate points when challenged, or retract them. Playing silly games will not win you any friends.

    Welcome to the forum.
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  14. #13  
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    I'm just trying to be helpful and add my 2 cents worth.
    I'm not arguing anything.
    I never made any assertion of any kind.
    I just said that 'it was my understanding'.
    I had no idea what the numbers would say or whether they would support yours or my opinion.
    I just thought that people might like to see some numbers rather than just take yours or my word for it one way or the other.
    I never said it was simple. Of course its all much more complicated than that.

    It is you who are being overly argumentative here.

    You cant say 2 words on any forum on any website anywhere on the whole worldwide web without being immediately attacked.

    you seem to view this as some kind of contest or jousting.
    Should we have a trial by combat and whoever wins is right?
    I just view it as people sharing bits of info.
    People should make up their own minds on these things.
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  15. #14  
    Universal Mind John Galt's Avatar
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    Quote Originally Posted by granpa
    I'm just trying to be helpful and add my 2 cents worth.
    I'm not arguing anything.
    I though people might like to see some numbers rather than just take peoples word for it one way or the other..
    You have provided selected data. I could likely find figures for extinction timings that differ from these. By providing selected data you are, inadvertently, arguing the position that there is a periodicity. I actually think there is a 50:50 chance the periodicity is real. I warm to the notion that the cause is Nemesis. However, a comprehensive look at the data do not support these views as yet.

    I fully accept that you did not intend the numbers to be seen that way, but that is the way they fall out. Since it was not your intention I retract my remark about 'passive aggressive'.

    However, note that I am not attacking you. I am correcting a position that I believe to be in error: namely that there is a 26 million year cycle in extinctions. There isn't; there simply may be. Some data support the notion. Other data do not. In such a situation it is vital that we stay away from absolutes.
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  16. #15  
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    They were the first numbers that I found in the first place I looked.

    http://en.wikipedia.org/wiki/Extinction_event

    except for one which I marked with a question mark and found here
    http://www.annualreviews.org/doi/abs...rnalCode=earth
    by google searching
    http://www.google.com/search?q=Eocen...ient=firefox-a
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  17. #16  
    Universal Mind John Galt's Avatar
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    How have those extinction events been defined? What time range do they extend over? How pronounced is the extinction rate above the background level? Can this peridocity be discerned for earlier epochs? Without substantive answers to these questions and similar ones your data are just a bunch of numbers.

    The consensus view remains that no clearly defined peridocity exists. It is a valid and valuable avenue of research to continue investigation of possible cycles in extinction events, but a blanket statement that extinctions occur on an approximately 26 million year cycle is at best premature and at worst simply wrong.

    You say you do not wish to argue the point, then present your numbers, thus arguing the point. I believe this is known in psycho-speak as 'passive aggressive' behaviour. This is a discussion forum: either debate points when challenged, or retract them. Playing silly games will not win you any friends.

    Welcome to the forum.
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