Re: Evolution Statement

From: Keith B Miller (kbmill@ksu.edu)
Date: Sun Dec 09 2001 - 21:00:34 EST

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    Burgy wrote:

    >Thinking a little (perhaps VERY little), there are several reasons why I
    >am skeptical that macroevolution is "microevolution writ large."
    >
    >snip<
    >
    >3. The fact that animals appear in very definite classes, cats, dogs,
    >elephants, etc. Yes, I know the "niche" arguments, but they are not
    >really very satisfying.

    I will make a brief reply to the above comment. Thge fact is, the
    boundaries between taxonomic groups are NOT clearly drawn. When you move
    back in time toward the time of appearance of a new taxonomic group,
    distinctions become less and less clear. It is a very common occurrence in
    paleontology that there is considerable uncertainty and disagreement among
    workers regarding the proper classification of early appearing forms. The
    morphologic features that define recognized living groups do not appear in
    the fossil record simultaneously. Thus some fossil forms bear some but not
    all defining characters of a living group, and some bear the defining
    characters of more than one distinct taxonomic group.

    This pattern characterizes the appearance of many class level groups --
    mammals, birds, reptiles (amniotes), amphibians (tetrapods), bivalves,
    gastropods, scaphopods, rostroconchs, etc.

    Keith

    Keith B. Miller
    Department of Geology
    Kansas State University
    Manhattan, KS 66506
    kbmill@ksu.edu
    http://www-personal.ksu.edu/~kbmill/



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