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Re: Beaks



In a message dated 4/18/99 7:52:30 AM Central Daylight Time, ornstn@home.com 
writes:

<< >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. >>

I have an old video on the Maiasaur which mentions that the babies had a 
tooth like structure on the nose used to break through the egg and then fell 
off later. Is this something they know? Has there been fossils of this 
structure found or is this just a speculation. The video is actually a 
children's book read on tape and it has a lot of behavior stuff in it that 
I'm sure is just a theory, if even that. Thanks.


                                                                                
                                                                ~Matt