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Re: Embryological evidence that bird fingers are I, II, III



2011/8/11 Thomas R. Holtz, Jr. <tholtz@umd.edu>:

> So the frameshift specifies that it isn't simply that "digits II to IV 
> assumes the anatomies of digits I to III"; it is
> "condensation positions II to IV develop into anatomical digits I to III". 
> They ARE digits I-III from all gene-product standpoints.
>
This would also include embryonic gene expression, right? Vargas and
Wagner have provided other evidence from gene expression that bird
digit identities were I-III, yet they interpret this as congruent with
the frame shift. What makes the new gene expression studies think that
the observed gene expression is more constant (from the viewpoint of
their relationship with original condensations) than the primary axis,
as to be a better hallmark of condensation (to avoid saying digit)
homology? Greater constancy in relationships with the condensations?
Let me say I am biased, not sympathetical to this hypothesis (not with
BANDit interests), and the fact that there are known remains of two
digits behind the minor metacarpal makes me happy!

Cheers,

Augusto