Re: Beaks in Ornithomimids

["Jaime A. Headden" <qilongia@yahoo.com>]

I wrote:

<<Loss of teeth does not result in a sharp tomial edge, as the tomial edge is a 
derived condition
beyond the reversal of tooth loss... the reduction of the teeth on troodontid 
jaws does not result
in a sharp caudal edge, and the same can be said in primitive birds, which have 
rounded toothless
margins of bone behind the dentigerous portion of the jaws.>> 

Graydon "Graydon" Saunders (graydon@dsl.ca) wrote:

<Loss of teeth directly, no, but if the teeth are still there there's a certain 
minimum width to
the top margin of the tooth-bearing bones; if the teeth aren't there, the jaw 
is free to develop a
shape that supports the stresses on it without having to support teeth, too.>

also....

<Anyone know of biting stress studies for ornithomimids? The one skull I've 
seen (in the Royal
Ontario Museum) looks very delicate. I don't think they would be able to 
generate much biting
force, even with a beak; that's what I'm taking as most of the argument for 
what-it-can-
swallow-whole omnivory, I don't think tearing things up was much of an option.>

  Jorn Hurum is currently involved on this, along with studies of tyrannosaur 
bite stresses. Check
out:

  Hurum, J.H. 2001. The lower jaw of *Gallimimus bullatus*. p. 34-41 in Tanke 
and Carpenter (eds.)
  _Mesozoic Vertebrate Life_ (NRC-CNRC & Indiana University Press [Bloomington 
& Indianapolis]).

I posted on this paper a while back...

=====
Jaime A. Headden

  Aaaaaaaaaaaaaaaaaaaahhhhhhhhhhhhhhhhhhr-gen-ti-na
  Where the Wind Comes Sweeping Down the Pampas!!!!

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