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Re: Sauropod necks and blood pressure




On Tue, 14 Mar 1995, Mikiel wrote:

>       Here's a silly question I thought I'd throw out to stir up some 
> more talk about the necks of sauropods.  Perhaps someone out there who's 
> familiar with giraffe anatomy can answer this one.  Supposing for a 
> moment that a sauropod's heart is carried rather close to the vertebral 
> column, wouldn't there be at least some "siphoning" effect in the blood 
> column of the neck?  After all, if the blood on the return trip to the 
> body mass enters any large organ where it's allowed to pool, and the 
> blood leaving the heart for the brain leaves the heart _above_ the level 
> of the "pool," wouldn't the weight of the blood in the return column at 
> least partially offset the pressure required to pump the blood up in the 
> first place?  Not to say that high systemic blood pressures wouldn't 
> still exist in the animal's neck, but would the heart have to do all the 
> work?  Or is gravity helping to some degree?  I saw some speculation a 
> few years ago that sauropods would need up to eight hearts to pump blood 
> UP the neck, so I'm wondering if blood perfusion to the head effectively 
> nullifies the siphoning effect of the blood in the return column.
>       Of course, I don't know that the heart in sauropods is situated 
> above the level of any organ which could pool the blood (perhaps the heart 
> itself?), but I thought I'd ask.
> 
> -Mikiel
> 
  Another log  to toss on the fire is that the blood pressures described 
would make an attack on a sauropod a very sketchy situation all a 
predator would have to do is puncture the jugular and their toast (in a 
matter of speaking) and also if they had to raise their head quickly they 
had to have a valve to ease the pressure while escape to prevent blowing 
their heads off(which could get messy) why not build a scaled anatomic model 
and really test the pressures needed, this may give us some other ideas 
and theories.  Ideas anyone? 

Aaron Feuk
Preparator,Dept. of Earth Sciences 
Pacific Lutheran University
Tacoma, Wash. 98447