re: Poling marks

[David Peters <davidrpeters@earthlink.net>]

DM wrote:

Pterosaurs are front-heavy, so the foot
prints are expected to vanish in higher sediment layers than the hand
prints.

>>>>

Not so. Check out pterosaur info. com > behaviors for an animation of a
walking pterosaur that actually fits the tracks. It's essentially
bipedal using its forelimbs as canes. And, if you can imagine using a
cane at the beach, you'll understand why the forelimbs press a little
deeper. Less surface area.



DM; Pterosaur walks on soft mud on all fours, many layers of
mud get deformed, the top layers erode away, and one of the underprint
layers ends up being published.


>>>>>

In every case? Seems unreasonable.


DM wrote:

Maybe that's where the multiple naris comes in.

It does not exist. It is a misinterpretation of cracks in the fossil.
Several people have pointed this out onlist.


>>>>>
No. They haven't. Not with pictures. And funny that the cracks form
identical phylogenetic patterns. That's unreasonable.


DM wrote:

Why? Jim has pointed out that it's physically impossible. The only worth
of this idea is that many of us have learned a bit more about  basic
aerodynamics/biomechanics.



>>>>>
I join one and all in my respect for Jim's abilities. And yet, even he
has not come back from the Cretaceous with a butterfuly on his boot
sole. Some things are yet to be discovered. Some things are worth
considering other options. Tell me David, if _some_ poling marks turn
out to be primary ichnites, does that change any of your hypotheses?

David Peters
St. Louis