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Re: AMARGASAURUS SATTLERI (pretty long)



Patrick Norton wrote...
>This is a preposterous statement, on its face.  I refuse to accept that I
>couldn't differentiate you from a ostrich. Come on...


    If telling two species apart seems like something a six year old could
do, consider ring species.  In northern europe live two species of gull, the
herring gull and the lesser black-footed gull.  They are clearly distinct in
appearance, and they do not interbreed.   In North America, there is (for
the most part) only the herring gull.  However, as you move across northern
North America across northern Siberia and into northern europe, you
encounter an almost continuous, interbreeding gradation from the herring
gull to the lesser black-footed gull.  To someone explaining the gradational
changes and the difficulty in drawing species boundaries along the gull's
distritbution, one might scoff "I refuse to accept that I can't tell a
herring gull from a lesser black-footed gull" and be right...but still
missing the point.
    Could you tell an ostritch from its ancestor 10,000 years ago? 50,000
years ago?  1 my?  1.5 my ago?  If you moved back in time in 10,000 year
increments along the ostrich family tree back to its common ancestor with
me, and then moved forward in time in the same 10,000 year increments, you
would encounter a continuous series of pretty much indistinguishible,
interbreeding forms.  If we want to ignore evolution doesn't exist and just
compare living ostriches and humans, then sure, distinguishing them looks
easy.  However, if we want to look at the entire family history of of life,
and use a system of classification that looks at the entire history of life,
the divisions as we start moving up and down the branches start seeming
fairly arbitrary.  Fortunately for taxonomy, most of the intermediates have
gone.

LNJ
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