Re: Beaks

[Ronald Orenstein <ornstn@rogers.com>]

At 01:31 PM 20/12/02 -0600, His Dark Lordship wrote:
> Is there any evidence/theories/facts to explain why our feathered friends,
> during their conquest of the skies in ages past, lost their jaws of razor
> sharp teeth in favor of one gigantic toothlike beak? What possible
> advantages are there to a beak? Disadvantages? Are we dealing with weight
> issues (although it seems to me a gigantic chunk of bone would weight more
> than a couple dozen smaller bones) or are beaks just more efficient for
> consumption of prey?

For one thing, teeth are not bone, but made of considerably denser material 
- so that a cutting edge made of tooth enamel will weigh more than an equal 
volume of bone (or of keratin, which actually forms the cutting edge on 
bird beaks).  Of course, that doesn't explain the loss of teeth in (say) 
turtles.

As for efficiency, I think that may depend on what you do with a beak or 
teeth.  The big advantages of teeth would seem to me to be their extreme 
hardness, their replaceability in the case of wear or injury (though the 
cutting edge of a beak can be regrown) and their capacity for diversity of 
function (as best seen in mammals).  Their disadvantages are probably 
related to weight and the metabolic costs of growing and maintaining them.


--
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@rogers.com