Re: Sauropod nostrils (was RE: joke........)

[carlo godel <regiaero@gj.net>]

Tom,
In all of the animals you mention the internal nares still come very close to
the braincase especially in the Camarasaurus, the others I can not say as I
don't have any specimens of those available for study. I may be misinformed but
I remember reading that some frogs are capable of respiration through the skin.
My Idea is not that far fetched, perhaps out on a limb? I did not bring a saw.
thank you
Carlo




Thomas R. Holtz, Jr. wrote:

> > -----Original Message-----
> > From: owner-dinosaur@usc.edu [mailto:owner-dinosaur@usc.edu]On Behalf Of
> > carlo godel
> >
> >However the blood that remained in the head region could have been
> > oxygenated by the mere act of breathing since the nostrils were
> > placed in such
> > proximity to the braincase and the nasal cavities passing
> > directly to both sides
> > of the braincase there was no need to bring the blood up to the
> > brain as it was
> > oxygenated from the passage of air over the nasal membranes and
> > hence to the
> > brain cavity. Just as cocaine does or phenylephrine HCl.
> > does. The passage of air over the membranes would act as the pump for the
> > circulation, inhale and exhale would apply pressure to the passage. The
> > transition from one to the other would release the pressure.
> > Hence no need to get
> > blood up to the brain against all of that fluid head cause it was
> > already there
> > and circulation provided for. Why have your nostrils at the top
> > of your head if
> > not for feeding your brain?
>
> An interesting hypothesis, but please note:
> Not all sauropods, or even all long-necked sauropods, have nostrils at the
> top of their head.  In _Shunosaurus_, _Omeisaurus_, _Mamenchisaurus_,
> _Euhelopus_, and _Camarasaurus_ (to think of a few off the top of my head,
> so to speak...) the nostris are still anterior to the orbits and certainly
> far less retracted than in (for example) diplodocids or brachiosaurids.
>
> As for other reasons for putting nostrils at the top of your head:
> Breathing while most of the body is underwater (okay, does not work for
> sauropods, as established long ago, but in vertebrate history this seems to
> be the main factor in narial retraction);
> Attachment for proboscis: has been suggested for sauropods, but little else
> to support this idea;
> Attachment for inflatable nose bladder: might work for macronarians, but
> unlikely for diplodocids.
>
> And, of course, simply getting the nostrils out of the way of the feeding
> area, so the sauropod could be munching leaves without getting twigs in its
> nostrils...
>
>                 Thomas R. Holtz, Jr.
>                 Vertebrate Paleontologist
> Department of Geology           Director, Earth, Life & Time Program
> University of Maryland          College Park Scholars
>                 College Park, MD  20742
> http://www.geol.umd.edu/~tholtz/tholtz.htm
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> Phone:  301-405-4084    Email:  tholtz@geol.umd.edu
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