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Re: Unidirectional gator breathing in Science
--- On Thu, 1/14/10, email@example.com <firstname.lastname@example.org> wrote:
> Jeez, an irrelevant to the idea paper in Science and deep
> sauropod drivel.
Actually, I stated that due to incorrect and tacit assumptions about sauropod
respiration, the _falsification_ of the "snorkel theory" may be falsifiable. I
would indeed consider standing at 2 atm (10m depth) and breathing surface to be
unlikely, but then I consider that a sauropod holding its' neck straight up to
be a little much as well.
> Because sauropods were so pneumatic they would have
> chronically floated,
> not sunk to the bottom like nonpneumatic, heavy boned
> aquatic animals.
Perhaps, if Henderson is correct, and did not underestimate the density of the
lower limbs. However, in previous discussion(s) on the list, claims were made
that a sauropod merely up to its' shoulders in mud (or watery mud) would have
difficulty breathing due to pressure. I consider those claims doubtful.
Further, as mud resists movements of the legs, the 'tipsy punter' scenario
would not apply in swampy conditions, anyway.
> None of the examples cited breaths with the body under high
> water pressure
> (humans can breath through a tube a couple of feet under,
Only for a short period of time; 2' is very difficult, perhaps dangerous, for
most humans. I have seen claims of 6', but am skeptical.
> surface swimming
> snorkeling elephants breath with the lungs a few feet below
> the surface).
Given that they must move that water w/ their diaphragms, while drawing air
through the trunk, that is very impressive performance from the elephants,
don't you think? Given the larger amount of power sauropods possessed, any
inherent advantage to their respiratory system might well have allowed them to
breath under more than 1.2 atm abdominal pressure (2m depth).
As an aside, another point frequently missed in consideration of possible
sauropod lifestyles is the fact that 'dive time' is proportional to bodysize.
Given their 'airiness', sauropods could likely have held their breath an
impressive length of time even in the absence of specific adaptations.
> Water pressure more a couple of meters would have prevented
> regardless of respiratory design.
I will accept that statement (or guess?) when I see some data on the abilities
of birds. As none currently exists (apparently), it might be a while, but will
come someday, I hope.
I note that a person can exert _considerably_ more than a mere 1.2 atm pressure
when holding a chicken or duck. While thoracic compression is used historically
to "euthanize" birds, it is not recommended on larger birds due to difficulty
and slowness. I also note that none of the birds that I held when I was growing
up suffocated, even though I would never have held a dog that tight (and would
have been bitten immediately had I tried).