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Re: Fwd: Removing segnosaurs from Theropoda



>
>        You cannot determine whether or not a character state is convergant
>between two taxa until after your analysis has been performed.  To state
>that a character is homoplasious before hand is an a priori hypothesis,
>which is the staple of religion, NOT science.  It is the analysis that
>determines the status of a character.
>
>        Jason Head
>        Dept. Geological Sciences
>        SMU

This is rediculously circular. Of course a detailed analysis of morphology
can reveal convergence without a phylogenetic analysis ever being
performed. In a crude analogy (and I love being crude), even a cursory
study of the morphological convergent characters of sharks, ichthyosaurs
and dolphins will reveal their convergent nature. In this sence, convergent
characters _must_ be identified prior to analysis, particularly where a
suit of characters can be demonstrated to be convergent. If this is not
done then the analysis will be artificially weighted in favour of a
paraphyletic group based on convergent characters.

Cheers, Paul

pwillis@ozemail.com.au