Re: Conway's Nyctosaurus Restoration

[David Peters <davidrpeters@earthlink.net>]

The two specimens were each reconstructed differently, chiefly in the chord
of the proposed sail. Does the smaller chord, taller mast change the
equation? Or visa versa?

Or ~ is one reconstructed in error? Perhaps one should match the other
better?

DP

"James R. Cunningham" wrote:

> 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