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Electronicly published: why don't modern birds have teeth?

A new paper, to be printed in the next issue of the Proceedings of the
National Academy of Science, and currently in an on-line Early Edition form:

YiPing Chen, Yanding Zhang, Ting-Xing Jiang, Amanda J. Barlow, Tara R. St.
Amand, Yueping Hu, Shaun Heaney, Philippa Francis-West, Cheng-Ming Chuong,
and Richard Maas.  2000.
Conservation of early odontogenic signaling pathways in Aves. Proceedings of
the National Academy of Science Early Edition (On-line): PNAS published
August 22, 2000, 10.1073/pnas.160245097 ( Developmental Biology )

At the website: http://www.pnas.org/papbyrecent.shtml

A developmental biology paper explaining why modern birds don't have teeth,
from a developmental biology perspective.

They demonstrate that three molecules required in odontogenesis (tooth
formation) in other vertebrates are not expressed, and speculate that even
if supplied that chickens wouldn't form true teeth (in all likelihood, the
net effect of a Cenozoic Era's-worth of mutations would have transformed
some of the genes utilized in the initiation and development of teeth into

                Thomas R. Holtz, Jr.
                Vertebrate Paleontologist
Department of Geology           Director, Earth, Life & Time Program
University of Maryland          College Park Scholars
                College Park, MD  20742
Phone:  301-405-4084    Email:  tholtz@geol.umd.edu
Fax (Geol):  301-314-9661       Fax (CPS-ELT): 301-405-0796