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Re: Great blue heron - Pterosaurs



RE: Crest function-- Yes, sexual
preference/territorial display are always front
runners. Is the fossil material good enough to
determine if sexual dimorphism exists in ptero's/ptero
crests? If it does, that is strong support...

Or a large skim-fishing ptero might find an inertial
counterweight useful to counter the down-and-back
pivoting impact that occurs when beak meets water (and
fish). Seems like that could increase the strike
success ratio. I'd be real surprised if that's a new
idea, and it is possible I read it somewhere. Has it
been discounted or rejected? Or discussed? Perhaps it
could be reasonably combined w/ my usual default
explanation for bizarre protuberances,
thermoregulatory function.

Aerodynamic advantage-- How would that work? Were
crests really large enough to generate useful
aerodynamic force at the slow speeds involved in
surface effect soaring (I'm thinking Great Albatross
here)? Of course, big as they were, they may have had
difficulty banking or using their wings for turning
when close to the surface. Sort of a front rudder or
canard-type effect?
 
--- "James R. Cunningham" <jrccea@bellsouth.net>
wrote:
> 
> 
> don ohmes wrote:
> 
> > So when the crested ptero's flew, what was the
> > probable angle of the crest relative to the
> ground?
> > 45??
> 
> Depends upon the species.
> 
> > Any consensus or front running theories on crest
> function?
> 
> In my personal opinion, their primary function was
> likely to have been
> sexual or species recognition, and the maximum crest
> size would have
> been limited by aerodynamic constraints.  I would
> predict that no truly
> long-necked pterosaur will be found to have a large
> crest, unless that
> crest is collapsible, and that maximum crest size is
> likely to be
> inversely related to neck length.   It is also
> possible that some
> species (or genders) may have been able to use large
> crests to exploit
> the energy available at the boundary of a fluid
> interface (sailglide
> skimming, for example).
> 
> As an aside, the long-necked azhdarchids that I work
> on had very limited
> neck mobility and could not achieve anything
> approaching heron neck
> positioning.
> 
>