Re: Conway's Nyctosaurus Restoration

["James R. Cunningham" <jrccea@bellsouth.net>]

David Peters wrote:
> 
> Was wondering if the super-crest did indeed frame a sail-like dermis?

No one knows yet.  When one hypothesizes that the crest was not
appropriate for supporting a membrane sail because the balance of
aerodynamic and hydrodynamic forces would be unsuitable and then
performs check calculations on the hypothesized sail, the calculations
demonstrate that the crest shape, form, and forces developed were
remarkably appropriate for providing thrust by sail-glide-skimming in
ground effect where the required sideforce resistance could be provided
either by the lower mandible or by wingtip-water insertion. In either
scenario, the sideforce production is appropriate.  With membraned
crest, the animal would have been capable of sailing as close to the
wind (upwind) as can the best racing yacht, perhaps closer as we refine
the calculations.  Required windfield was checked against GENESIS
supercomputer calculations of the mean windfield and surface currents
acting on the Western Interior Seaway during the early Turonian and that
was found to be an extraordinarily good match to the
aerodynamic/hydrodynamic requirements.  Therefore, the
sail-glide-skimming technique is worth further study and a search for
evidence for OR against the presence of an actual membrane.  But the
analysis doesn't mean that the Nyctosaurus crest did support such a
membrane.  I have become personally convinced that it does, but actual
proof or disproof has not been established.

Note that the membrane crest cannot be used for providing thrust for
soaring at altitude unless the sail is operating in a regularly
undulating sinusoidal windfield with a variation substantially greater
than 0.2 of the average.  Unlikely to the point of improbability.  

> There is a funny-looking dermis-like matrix _anterior_ to the "main
> mast" in one of the specimens,

> And what is that funny-looking dermis-like matrix _anterior_ to the
> "main mast"?

That is painted and the texture may be preparation marks.  I don't know
yet.  Chris Bennett may know.
 
> Great painting!

It sure is.  It is likely that the animals would usually be operating
slightly more to the windward side of the wave crests. John is aware of
this, but says the media isn't suitable for modifying the image.  And
they could operate right on the top of the swell.

JimC