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Re: Sauropod Energetics (Peristaltic pump)
I've posted several times before about the possibilities of higher O2
levels, and some of the ramifications. [I'll dig up the postings, which
have references, if needed].
I won't repeat it all here, except to say that some currently suspect
studies on gases preserved in amber indicated that the O2 level was as high
as 35%, nearly double our current level, and just under a theoretical
maximum for our atmosphere (It is _suspected_ that higher concentrations
would lead to spontaneous combustion of the atmosphere).
The studies indicated that the O2 levels varied up and down over the last
230 my. [The amber gases seemed to have such GREAT data].
Amber, unfortunately, apparently does leak some gases, in unknown and
unequal rates (over millions of years!); so that the actual O2 level is very
difficult to determine. Newer tests involving natural Carbon sequestration
rates (in oceanic sediments) may help us determine the true levels of O2,
but I don't know how far these tests have come in the last 2 years.
Some things that might be helped by increased O2 levels: The extreme sizes
of many dinosaurs (especially sauropods) would be easier to support in
higher O2 - the muscles would work better with the additional O2 (allowing
them to carry more weight per pound of muscle); and, as you suggest, the
blood that did reach the brain would have more O2, to allow better
functioning when (IF!) the head was raised much above the 2.5 meter distance
from the heart.
The blood pressure would not need to be as high to maintain sufficient O2 to
the brain. [Some workers have suggested that the largest sauropods may have
lived (conservatively) up to 150 years, and some have speculated as much as
1200 years! These ages would be somewhat easier to achieve with lower BP].
Hope this helps,
From: "Richard W. Travsky" <firstname.lastname@example.org>
Subject: Re: Sauropod Energetics (Peristaltic pump)
Date: Tue, 31 Jan 2006 09:23:15 -0700 (MST)
On Thu, 26 Jan 2006, Sim Koning wrote:
Would some sauropods need to maintain blood flow in order to raise their
heads long enough to take a mouthful? Surely if a diplodocid (or other
species that maintained horizontal necks most of the time) was able to
seal off the blood supply out of the neck for a few seconds to prevent
blood from draining away from the brain, then a few moments of no blood
flow to that tiny brain wouldn't be so critical?
It would mean they couldn't raise their heads for any length of time
(barring other unknown blood flow mechanisms), but it wouldn't make
quick forays into higher elevations entirely impossible.
That's Bakker's hypothesis, but I don't know how long even a small brain
could function without a constant oxygen supply. It would mean that these
Would higher oxygen levels compensate?