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Re: Pterosaur wings and refs




"James R. Cunningham" wrote:

> David Peters and David Unwin wrote:
> >
> >> Add to this Hazlehurst's (1991) discovery of a good correlation between 
> >> fore and hind limb length in pterosaurs,
> >
> > This is probably true because in a balanced standing bipedal pose the
> > distal metacarpus of nearly all pterosaurs will touch the ground, or at
> > least the ankle, by simple elbow extension (short-armed Austriadactylus
> > and Campylognathoides zitteli are the sole exceptions).
>
> But there are exceptions, implying non-bipedality in at least some
> pterosaurs.

Or, as in these cases, quadrupedality requires abit of bending over. That's all.
Bipedality is a constant. I've done the reconstructions. They all balance over 
the toes using the center of balance,
as in all flying animals, just aft of the humeral glenoid.

> In the animals I mess with, I've never seen much need for a
> balanced standing bipedal pose,

Of course not, Jim. You deal with Quetzalcoatlus. It spent all day standing on 
all fours! And it was part of a clade
which did likewise.

>
> > I can send Internet links to mpg movies of same if interested.
> I'm interested, but my antequated computer craps out on mpegs.  I'd like
> to have the links anyway.

The Irschick Lab   >>     http://www.tulane.edu/~irschick/
The Jayne Lab       >>     http://www.biology.uc.edu/faculty/jayne/bruce.htm

These will get you started.

>
> > quadrupedal plantigrady - as shown y thousands of pterosaur tracks,

?And one French quadrupedal digitigrade track with a posteriorly-directed 
dorygnathid-like bent fifth toe. Then a big
gap and Rotodactylus in the Triassic, again with a posteriorly directed fifth 
toe. Us digitigrade guys are
underrepresented because the filter-feeders and waders leaving all the tracks 
are the flatfoots. The digitigrade
pterosaurs are of the soaring sort.

> Boy, you got that right.  Particularly since it seems that the chord is
> actively variable,

Not variable. Sorry. The actinofibrils will not permit it.  BTW, Just found out 
the reference will be Historical
Biology 15, pp. 277-301.

More later,
David Peters