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More on Birds, dinosaurs, and digits



Well, I finally caught up enough on reading _Science_ to read the Burke &
Feduccia paper on bird digits.  As I suspected, it isn't as conclusive as
they would like us to believe.

In fact I noticed a subtlety that I do not remember seeing mentioned here
previously.  Looking at the pictures they show of hand development in
crocodilians, I saw something interesting.  While the "main axis" is fairly
clearly through digit IV, this main axis is *curved* laterally through the
metatarsals!  This leaves digit III as the one that is actually colinear
with the humerus.  So asked myself, what would the result be if digit IV
reduced in size, and perhaps digit III increased in size, to the point
where distal metatarsal IV was substantially smaller than distal metatarsal
III?  From the looks of things, such a process would, with *no* *further*
*changes*, be sufficient to shift digit III onto the "main axis".  No need
for subtle changes in proportions in the adult.

--------------
May the peace of God be with you.         sarima@ix.netcom.com
                                          sfriesen@netlock.com