RE: Fluid Compressibility and Dinosaur Social Warmth

["Al Fraser and Laurie Fletcher" <alflaurf@abs.net>]

There has been a misunderstanding about the meaning of the compressibility
of water as it relates to biological roles of sclerotic rings.  The
misunderstanding seems to arise from a combination of inaccurately reading
what I said, and non-quantitative thinking.

Ray Stanford said:

    "Yes, indeed.  Haven't we all heard of sonar?  -- and, for that matter,
those well-documented recordings of the 'songs' of whales?  Those whales
were not 'singing' in the open air, whales have ears to hear under water,
and whale 'songs' have been recorded using aquatic microphones.  Water is
being usefully compressed (modulated compression) for such purposes.".......

It is true that the compressibility is one of the water properties that
supports underwater acoustics.  Nevertheless, the compressibility is very
small, and it is the quantity that I reported.  The fact that sound
propagates under water does not mean that water's compressibility is high or
in any way relevant to the paleontological point that was under discussion.
(And, yes, I have heard of sonar, and I have built sonars, and I have heard
whales while I was underwater with them.)

Ray Stanford then quoted more of my post prior to writing:

    "O.K., that information is appreciated, but whales (and submarines) take
advantage of water's compressibility quite effectively at depths less than
3,000 feet, and I would be greatly surprised to learn that prehistoric
marine reptiles frequented the 3,000 foot depth.  So is water's
near-incompressibility at 3,000 feet really meaningful in the context of our
discussion?  Or, do we debate dinosaurs' ability to breathe at ten miles
altitude?"......

The compressibility of water varies little with depth.  I wrote that that
the change would be only 0.17% "as the water goes from the surface to 3000
feet deep" (not that it is a property of 3000 foot depths).  The purpose of
this example was to show that the compression would be slight even with a
large, but not impossible, 3000 foot plunge.  The fractional change in
linear dimensions of a water parcel going from the surface to, say, 30 feet,
would by 0.0017%.  It would also be 0.0017% compression for a dive from 30
feet to 60 feet.

The fact that sonar and whale songs exist does not mean that compressibility
of water would argue for it being a physical basis for the evolution of
sclerotic rings.  Citing the existence of the same phenomena provides no
quantitative information that can support or refute the paleontological
hypothesis.

The analogy about breathing at ten miles altitude is irrelevant.

Al Fraser