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Re: The birds vs. the pterosaurs




David Marjanovic wrote:

> > >   There are mechanics that suggest that the largest known
> > > pterosaur, at 200 kilos,
>
> So much? I thought *Quetzalcoatlus* was estimated at 86 kg.

The 200 Kg estimate comes from a recent, very good paper by Greg Paul.  Qn could
lift that amount (and more), but its aerodynamic wing performance appears to be
intended to support more like 150-160 Kg or thereabouts during normal cruise at
a CL of about 0.9-1.0, and my still incomplete mass estimate seems to be
consistant with that number (so far).  Even ignoring the weight of the skeleton,
86 Kg would not have provided enough muscle, tendon, and ligament mass to
operate the system.  To give an idea of size, I just laid my two open hands
thumb to thumb tranversely over the distal end of the left humerus.  Skeletal
material of the joint is still visible all around the perifery of my two hands.
It takes a lot of supporting material to operate an articulaton of this size,
and as coorboration of a sort, there is a spanwise tendon or ligament passage on
the lower surface of the humerus at the elbow that is well over an inch in
diameter.

> > > could bear on its wings _well_ twice
> > > that value.
>
> :-o Cool...

It could indeed do that, both during transient gust loads, and during the
flapping downstroke.

Jim