Re: Testing the "why" of Giraffe necks...

[don ohmes <d_ohmes@yahoo.com>]

Heh. "Wow, what a surprise" is the category I would put this in. Good that it 
is done, though.

For those who don't object to a little speculation opposing the current null 
hypothesis of 'steady-state' atmosphere, it might be interesting to note that 
although the gravity force the heart would have to overcome to pump blood to a 
given height would remain the same over time, a higher atmospheric pressure 
would "reinforce" the artery wall by increasing the ambient pressure acting on 
the external wall. If the limit of  'head-over-heart' height is the strength of 
the artery rather than the pressure the heart can generate, a denser atmosphere 
would therefore allow a longer neck (ie, a greater head/heart height 
differential). By 'strength of the artery' I refer of course to the ability of 
the artery to resist aneurysm due to a positive differential between internal 
and external pressure (internal p - ambient p > 0).

Don

----- Original Message ----
From: Guy Leahy <xrciseguy@sbcglobal.net>
To: dinosaur@usc.edu
Sent: Saturday, December 23, 2006 10:02:22 PM
Subject: Testing the "why"  of Giraffe necks...

Interesting research... with obvious analogies to
sauropods... :-)

http://www.journals.uchicago.edu/press/122206_AN.html

Happy Holidays,

Guy Leahy