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Re: nostrils?






>This is just a guess, but I wonder if it might have something to do 
with
>the development of the ramphotheca, the horny sheath that covers the 
bills
>of modern birds.  Possibly the migration of the nostrils to near the 
base
>of the sheath in some way strengthens the thing structurally, or 
possibly
>makes it less likely that the nostrils will get clogged or injured as 
the
>bird uses its beak for pecking or probing.  

     It should be noted that the posteriorly displaced nostrils are not 
seen in enantiornithines. And there is little concensus on whether they 
had rhamphothecacus beaks. And also this "displacement" may be more 
apparent than real. It probably has to do with the edentalous beaks seen 
in Neornithine birds ( possibly basal in Aves?) where a large extension 
of the premaxilla was developed to accomadate a beak. This caused a 
"shift" in the position of the nares in general appearance. But it 
should be noted that Confuciusornis and Gobipteryx ( please note that I 
do _not_ endorse a close relationship between the taxon contrarily to 
Hou et al. 1996) do not show a marked shift in the position of the 
nares. 
     Just a few thoughts.


 WMattTroutman



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