Re: Question: Why did birds lose their teeth?

[Dann Pigdon <dannj@alphalink.com.au>]

On Tue, Mar 11th, 2014 at 1:16 AM, Martin Baeker <martin.baeker@tu-bs.de> wrote:

> I once learned that losing teeth was a weight-saving measure and thus
> a flight adaptation. There is this reference stating this  as a possibility
> http://www.newscientist.com/article/dn18248-early-birds-may-have-dropped-teeth-to-get-
airborne.html#.Ux3HhdsjulM
> 
> However, I seem to remember that there was some study showing that
> birds actually do not lose signifcant weight by replacing teeth with
> beaks - if anybody has a reference on this, I'd be grateful.

There may not have been a single source of selective pressure for loss of 
teeth. A whole lot of 
separate minor advantages may well have added up.

Constantly shedding and replacing teeth might have been an expensive use of 
calcium, for 
instance, that could otherwise be used to stengthen bones against the rigours 
of flight, or for the 
production of hard-shelled eggs that were larger relative to body weight than 
those of non-volant 
theropods.

The weight of the teeth themselves may not have been the only weight-saving 
advantage either. 
The lack of teeth might have allowed the jaw bones to become more slender, 
making it possible to 
make do with a much more light-weight skull. The jaw bones of tooth-bearing 
creatures are 
generally the toughest bones in the body (which is why jaw bones are so common 
in the fossil 
record). In some modern birds, the mandibles are little more than whispy 
splints of bone once the 
beak has been removed.

-- 
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Dann Pigdon
Spatial Data Analyst               Australian Dinosaurs
Melbourne, Australia               http://home.alphalink.com.au/~dannj
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