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Re: linguistic analogy

On Mon, 12 Feb 1996, Rob Meyerson wrote:

> >   It's my understanding that many dinosaurs have deep sternums.  The
> >sternum of _Mononykus_ is referred to as "keeled," as is that of
> >_Archaeopteryx bavarica_.  The only difference is that modern birds have a
> >HUGE sternum, whereas in certain theropods it was merely large.  Can a size
> >difference be sufficient to mark something as "different enough" for its own
> >category.
> One possible problem with this is that these two appear after Archy,
> AFAIK.  This would again suggest the possibility that the sternum
> solidified sometime later.

        The newest Archaeopteryx is supposed to have a sternum.

> However, if it can be shown that the sternum was already in place by
> Archy's appearance, I would have to say "No, they aren't different
> enough to put in different taxa."

        The newest Archaeopteryx is supposed to have a sternum. 

        Whether or not one group is different enough from another group 
to deserve an independent status is purely a matter of opinion. It is not 
going to be resolved by evidence. We can find all the evidence we want, 
perhaps it will imply greater or lesser morphological similarity than we 
now recognize. But similarity and dissimilarity are relative terms. 
Whether birds deserve their own special category apart from everybody 
else is a matter of opinion. How birds descended from other animals is 
not a matter for opinions, however, but for testable hypotheses. 
        How we choose to label critters is a human construct that may change
 the way in which we concieve of or talk of the creatures we call birds,
 but which will in no way change their nature. 
        -nick L.