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RE: Long Horizontal Necks Re: Vertebrae of Early Sauropods



--- Eric Martichuski <herewiss13@hotmail.com> wrote:
> >From: "Richard W. Travsky" <rtravsky@uwyo.edu>
> >Question - what would the effects be on sauropod
> head and brain if it
> >quickly sung its neck around? Kinda like a
> centrifuge, with blood pooling?
> 
> Why would it need to swing the neck quickly?
> (admittedly, the 'cudgel' idea 
> probably needs to be nixed)  You eat the patch of
> foliage on the extreme 
> right, swing a foot to the left and continue.  When
> you reach the extreme 
> left, take one step, eat and then swing a foot tot
> he right.  All very slow 
> and deliberate and less stressful than continued
> walking.

To differ with you on this, Eric, why would walking be
more stressful for a sauropod than swinging its head?
Are you speaking here of caloric expenditure when you
say "stress"? Moving towards a standing food source
consumes only a trivial amount of an animal's energy
(even less for large animals,which although their
absolute caloric expenditure is greater than a small
animal's, is less in proportion to their size). 
> 
> There might also valves within the circulatory
> system to prevents just such 
> spikes of local pressure.  I admit, I'm stepping
> into the realm of rampant 
> speculation, but  I know flow-back prevention valves
> exist, so 
> "flow-forward" prevention valves aren't such a
> _tremendous_ leap.

They aren't, I agree. This was a hypothesis raised by
D.S. Choy and Altman in their paper, The
Cardiovascular System of Barosaurus: an educated
guess.The Lancet 340 (8818): 534-536.
> 
> The _real_ question is how would a vertical necked
> sauropod take a drink?  
> The minute it lowered its head, the increased
> pressure would basically pop 
> the skull right off. ;-)

Not if it had a structure similar to the rete
mirabilia of a giraffe or cetacean, which absorbs the
increased pressure by diffusing it into a network of
smaller vessels, then shunting it back into a larger
one. Even a brachiosaurid or euhelopid that kept its
head and neck at a relatively modest 45 degree angle
would have to deal with this problem, unless it got
all its moisture requirements from its forage. (See
Time-Life's Africa (Nature Series) and Jonathan
Kingdon's chapter on Giraffes in African Mammals: An
Atlas of Evolution in Africa.)
--Mark Hallett


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