Re: Birds, dinosaurs, and digit 1

[Jeffrey Martz <martz@holly.ColoState.EDU>]

> Alan Feduccia, chair of biology at University of N.C., Chapel Hill, is
> co-author of an article in Science stating that microscopic examination of
> bird embryos shows no sign of digit 1, even in vestigial form. "We consider
> this unequivocal evidence that birds" did not evolve from dinosaurs. Reason:
> Dinosaurs had digits 1, 2, and 3; birds have digits 2, 3, and 4, with no sign
> of a digit 1, even in embryos.

     All vetetebrates had five digits ancestrally, so if
the embryo starts out with less then that, it is skipping earlier stages
in digit development anyway.  The question is, how did the authors
determine that the "first" digit in the embryo is digit 1, rather then
two?  It must be based on the relative positions of the digit to the wrist
bones, which was, as I recall the basis for assigning brid embryos 2-3-4
when this work was done back in the early eighties.  How does Fedduccia et
al know that the first digit is"1"?
 
LN jeff
O-