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Re: Birds have "thumb" genes like alligators: free pdf



I had written:

<<David, not only are you using highly modified manus and digit reduction here, 
including a functionally monodactylous manus,

...

but you are also usin adult conditions.>>

and David Marjanovic had replied:

<Not a lot more modified than any bird wing.

...

Not for the alligator, where I used the paper's own photos of embryos.>

  And this is the point. To use embryological data, rather than adult 
specimens, to determine digit homology, then track known ontogenetic 
modifications. Praepolleces be damned, in this case. You were using modified, 
HIGHLY divergent manual morphologies and your own adult hand to determine some 
comparison to an embryological crocodilian. Is this not peculiar? 

  I don't even have that much to say on the topic of identifying embryological 
buds in different taxa, as I have no expertise nor do I have the files I once 
did by several of the authors on the various sides of the debate, but what I 
saw as the major reaction was that you pulled out your own hand and tried to 
use that as a case comparison in he argument. At what point can even YOU assert 
your own hand is not also 0-1-2-3-4-x, with '0' being the prepollex? You would 
then have to assert a paper tracking human manual development with Hox coding 
to determine this, and only THEN can you start asserting that your hand is in 
any way referrable to the condition. You gave an endpoint that was at this time 
completely irrelevant to the subject for which the authors were studying.

  Maybe I'm just being b****y right now, but I would think a logical study 
would try to FIND pieces, instead of knock them out of the puzzle.

  Cheers,

Jaime A. Headden

"Innocent, unbiased observation is a myth." --- P.B. Medawar (1969)