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Re: Sauropod Energetics (Peristaltic pump)



In a message dated 1/31/06 6:10:24 PM, rtravsky@uwyo.edu writes:

<< On Tue, 31 Jan 2006 GSP1954@aol.com wrote:
> Oxygen levels are irrelevant to the basic BP issue in tall sauropods. Either
> the blood gets up there or it doesn't, it's a matter of the mass density of
> water-blood.

I was responding to Sim Koning's comment about "a constant oxygen supply" 
for the sauropd's brain. If oxygen concentration were higher, the blood 
would be more oxgenated and it could better "ride out" a blip in the 
supply.

 >>

Megaherbivores spend a large portion of the day feeding. When a horse or 
bison grazes it does not keep lifting the head for a look around, it's too 
busy. 
It is also extra work which costs some energy. If some, many or all sauropods 
spent a large portion of their average daily feeding time high browsing, 
lowering the head repeatedly to keep the brain running would interrupt feeding 
on a 
frequent basis, and cost some energy. Of course a high energy, high pressure 
cardio-circulatory system has a high metabolic cost, but that eliminates the 
very high risk of death from fainting and falling every time a tall, low BP 
sauropods makes a mental boo-boo and keeps it's head up too long. Chronic head 
lowering is an inherently dangerous and apparently selectively ill advised 
strategy. 

G Paul