Re: pterosauria arm folding

[NJPharris@aol.com]

In a message dated 97-06-19 08:14:22 EDT, sprea@linknet.it (Andrea Spreafico)
writes:

> As C. McGowan (Dinosaurs, Spitfires & Seadragons, 1991) points out,
>  rhamphorhynchs had a right, stiff tail, with long vertebrae's processes;
so
>  it may have been not only important during flight, but also an
equilibrating
>  organ on the ground. By this author, at least long-tailed pterosaurs could
>  have been bipedal.

If I might be permitted a moment of unbridled speculation, my working theory
of pterodactyloid evolution goes a little something like this:  a group of
Jurassic pterosaurs develops certain specializations relating to feeding
(longer jaws, longer neck) and flight (most importantly a longer metacarpus).
 This makes the front end of the body too heavy to counterbalance, which
brings the animals down on all fours.  The long tail, which was principally
for balance on land anyway, shortens to a stump, incidentally improving
certain aerodynamic aspects.  Of course most of these changes would have to
occur simultaneously, and the whole thing smacks of a "just-so" story; but it
is something to think about.

Padian's running _Dimorphodon_ looks elegant and quite plausible; his
penguin-waddling _Anhanguera_ looks ridiculous.

Nick P.