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Re: subject material and Re: Dinosaur Discussion List Dictionary



In a message dated 95-10-25 11:51:41 EDT, rowe@lepomis.psych.upenn.edu
(Mickey Rowe) writes:

>>> APOMORPHY--n. A character state present throughout a clade but
>>> not present in any close outgroup of the clade.
>>
>>This is wrong?
>
>I've double checked Robert Carroll's _Vertebrate Paleontology and
>Evolution_*, and near as I can tell, the above is, in fact, wrong.  In
>the first place, it implies that you can determine whether or not a
>character state is apomorphic on the basis of that character state's
>distribution alone.  A cladistic analysis must include suites of
>characters in order for us to have any hope of it spitting out correct
>answers.
>
>

I make no statement about how or when a character state is determined to be
an apomorphy. I only want to explain what an apomorphy IS. There are no
implications in my definition. An apomorphy is present throughout a clade but
not in the clade's immediate outgroups. How it got into the clade is
secondary. How we determine whether a character is an apomorphy is secondary.
Whether or not the apomorphy diagnoses the clade is secondary. Whether or not
there is a suite of apomorphies is secondary. Whether or not the apomorphy is
later modifed within the clade is secondary. We can, of course, amplify the
definition by including some of this stuff in the form of examples.