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RE: courses

Bear in mind that there are still some constraints on the range of
available characters.  There is a limited matrix of available
morpho-spaces.  As an example, an vertebrate would be unable (or
EXTREMELY unlikely) to shed its skeleton (like an invertebrate molts its
exoskeleton) THROUGH its body.

Allan Edels 

-----Original Message-----
From: owner-dinosaur@usc.edu [mailto:owner-dinosaur@usc.edu] On Behalf
Of Daniel Bensen
Sent: Sunday, December 08, 2002 2:05 PM
To: 'John Conway'; philidor11@snet.net; dinosaur@usc.edu
Subject: RE: courses

>>However, my use of the word "must" was too strong, and probably 
worked counter to my point.<<
Ah, okay.  Not must.    So  "characters - as pieces of morphology - are
probably (or might be) functional, which reduces the possible characters
any organism can evolve (and pathways too)."

>>Which features? If you are talking about spandrels, then this is 
I didn't know what spandrels were until just a few seconds ago (google
search)---is this a correct definition?: Spandrels are features of no
value to an organism that exist only because the organism evolved along
the path that it did.  Vestigial structures would be spandrels, as would
things like the optic nerve passing in front of the light receptors in
vertebrate eyes.  

If that is the correct definition, then yes, I was talking about

>>I'll put my second point more clearly: the more successful adaptive 
(biomechanical and evolutionary scenarios) become, the less reliable 
cladistics becomes; due to the fact that both are attempting to explain 
morphology by different means.<<

But you can ameliorate that problem by focusing on features that are not
particularly adaptive in an organism.