Re: choana [was SOME SVP TIDBITS]

["Thomas R. Holtz, Jr." <th81@umail.umd.edu>]

At 03:33 PM 10/15/98 -0400, Norm King wrote:

>One is that the choana is the passageway by which animals get air into 
>the mouth/throat while keeping the mouth closed.  It appeared first among 
>sarcopterygians, and sarcopertygians plus tetrapods are "choanates".  It 
>includes everything from the external nostrils to the internal nostrils 
>(nares, if we're just talking about holes through the bone), or from the 
>external nostrils to the back of a secondary palate, for animals that 
>have one.  It is the whole passageway; there is no special name for the 
>passage between the primary and secondary palate.

[snippet]

>I suspect that the first definition was the original one.  Otherwise, why 
>have a separate word?  Then, through use (misuse?), it came to also mean 
>internal nostril.  I'm speculating.
>
>
>Anyway, now I feel better.  Thank you, Norm.
>
>You're welcome, Norm.

Yes, thank you, Norm.

It would indeed be interesting to find out the history of the term: I
suspect you are correct.

In any case, back to the original observations (at least, I THINK this is
where we started out...):

The internal nares (internal nostrils) of _Velociraptor_ and of spinosaurids
were shown at SVP (and the recent spinosaur paper by Taquet & Russell) to be
much further back in the snout than previously thought.

Thomas R. Holtz, Jr.
Vertebrate Paleontologist     Webpage: http://www.geol.umd.edu
Dept. of Geology              Email:tholtz@geol.umd.edu
University of Maryland        Phone:301-405-4084
College Park, MD  20742       Fax:  301-314-9661