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Re: Large last gasp of pterosaurs



John Bois wrote:
> 
> There is no direct
> evidence of bad flying weather. 

Is there not?  :-)

  Also think about the competition between vultures and
> > hyenas.
> 
> Different, I think: aerial vs. terrestrial scavangers.

Not at all.  It's a direct case of 'time to target'.  The vultures
usually spot the target first due to aerial recon advantage. They then
advance toward the target.  Hyenas watch vultures.  When they see them
start to trend in one direction, they do the same.  Vultures get there
first.  When the hyenas arrive some minutes later, they drive the
vultures off. But the vultures had a few undisturbed minutes.  Similarly
in the case of one flying animal vs. another, the one with the heavier
wingloading wins the race.  See Pennycuick for a good, lucid
description. 


> Birds were more likely to be on even footing with other birds because of
> morphological similarity.  Ptrerosaurs were different.  I'm hypothesizing
> this difference led to a deficit on land, that they lacked terrestrial
> agility relative to birds.

Why not start with the opposite hypothesis, that the birds were
different in a way that led to an avian deficit on land? Or in the air,
I'm not particular.  Either way, you can then attempt to falsify the
hypothesis and see where it leads.

> I'm a victim of pop science portrayal of guy on crutches hypothesizing Q
> terrestrial movt on Making of WWD--was this way off?

It certainly seems so to me, but what do I know.  So far, I've not seen
a single pop TV portrayal of Quetz that reminded me in the least of the
actual animal.  Let me suggest that you actually spend some time
manipulating parts of the skeletal casts in terrestrial poses.  You'll
very likely come to believe  that they may have been very agile little
critters.

> Yes. And I would be very interested to hear your opinion of ptrerosaur
> nesting habits.

Pterosaur nesting habits are of little interest to me.  My talents, such
as they may be, are in flight mechanics, structural mechanics,
energetics, and the hydrologic cycle.  When it comes to nesting habits
or the lack thereof, I just listen to folks who are likely to know more
about that than me.  Ain't my specialty.


> Hey, you know what--I'm guilty of the same circularity as the bolide
> arguments for Q. extinction: birds must have had the edge because
> pterosaurs are extinct.

Birds did have a critical edge.  At the time, though they were inferior
fliers, for the most part they weren't soarers.  So when conditions
became unsuitable for flap-gliders and soaring for a short period of
time, some birds survived.  No flap-glider could manage that.  Which is
exactly what I've been saying all along.