New Paper concerning avian digits

[Michael Corriss <mcorriss@gate.net>]

Hello All!

Just received a notice of a new publication. Another addition to the
brew:


Editors' Choice: Highlights of the recent literature
SCIENCE, Volume 297, Issue 5587,  
dated September 6 2002, is now available at:

         http://www.sciencemag.org/content/vol297/issue5587/twil.shtml

EDITORS' CHOICE: HIGHLIGHTS OF THE RECENT LITERATURE
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DEVELOPMENT: Five into Three Is . . .
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Beverly A. Purnell and Sherman J. Suter

The identity of the digits of the avian hand has been hotly debated
since 
the 1820s. Early in development, birds display four cartilaginous
digits, 
with the distal digit (V) a rudimentary splint; however, mature birds 
possess only three ossified fingers. Studies of fossils and analyses of 
phylogenies suggest that the mature fingers are equivalent to digits I,
II,
and III of pentadactyl amniotes, but embryological evidence favors a 
homology of II, III, and IV. Two recent studies offer new results that
bear
on this question. Larsson and Wagner used molecular markers to identify 
digit condensations of chicken embryos, and Feduccia and Nowicki
examined 
the digit anlagen of ostrich embryos. Both studies identify a single
digit 
anlage that is in a proximal position relative to the three ossified 
digits. Hence, bird fingers develop from digit anlagen II, III, and IV.
The
findings have implications for the evolutionary relationship between
birds 
and theropod dinosaurs, which display a I, II, III digit identity.-- BAP
& 
ShJS

J. Exp. Zool. 294, 146 (2002); Naturwissenschaften
10.1007/s00114-002-0350-
y (2002).
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-mpc