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Re: Beaks



At 06:58 AM 18/04/1999 -0400, you wrote:
>Just saw a program about alligators on Discovery channel. It mentioned the
>keratinous "egg tooth", which is shed after the babies hatch. I was
>wondering if anybody has considered that this egg tooth might be a prelude
>to formation of a beak in creatures further along the evolutionary "ladder"?
>Could some form of  paedomorphosis be involved here?

I would very much doubt this - birds have an egg tooth too.  To quote "A
Dictionary of Birds" (eds. Campbell and Lack), it is "a small sharp
projection on the upper mandible of the full-term embryos of many species,
used in chipping open the egg shell during hatching.  It is usually lost
from the bill within a few days of hatching."

Turtles have a similar structure, the caruncle, which regresses rather than
dropping off after hatching.
--
Ronald I. Orenstein                           Phone: (905) 820-7886
International Wildlife Coalition              Fax/Modem: (905) 569-0116
1825 Shady Creek Court                 
Mississauga, Ontario, Canada L5L 3W2          mailto:ornstn@home.com