Re: poling and flying and bird refs

["Jaime A. Headden" <qilongia@yahoo.com>]

David Peters (davidrpeters@earthlink.net) wrote:

<Third, it sure makes everything easier if the pterosaur never goes past knee
deep waters. But those hands only tracks have to be accounted for somehow.
Ideas welcome.>

  David (Marjanovic) already offered that they are underprints, not surface
impressions or the intial contacty surfaces. Indeed, it has been argued by
Lockley, among others, that most tracks are underprints, which accoutns for
their being rather indistinct and showing limited details of the printing
surface (i.e., the pes/manus itself). Gatesy in his work on the Greenland mud
prints, and Mateus on the Lourinha sauropod print show what we can expect from
mud prints in primary contact surfaces. Miners have found from Europe to the
Midwest of the USA that cieling prints are underprints with the underlying
layers being mined (or in some cases, as in caves, eroded) away. They are not
the surface prints themselves, and thus anything that did not press more deeply
would result in compressing less substrate beneath it, be it mud, sand, silt,
or whathaveyou. Thus hands only prints may be highly viscuous material that
later dried out, and not true swimming traces. This also corroborates the very
anterior center of gravity in pterosaurs, though it is very unwise to use JUST
this case for the argument, though other studies, including fore AND hind
tracks support it.

<Fourth, poling marks are undertracks? Not likely considering the weight
involved, mostly supported by water.>

  As above, the trace would need to dry out to be preserved, which argues the
traces may not have been underwater. If tidal, which would allow rapid exposure
and then drying, or then burial by heavy sediments and thus preservation, the
water would not have been at all too deep. This suggests the prints were
shoreline, bank, or other mud-concentrated regions favorable to high
water-saturated sediments that would dry relatively quickly.

<Fifth, I'm not sure how the air-filled skull would descend unless, perhaps,
some allowance for some water to enter some chamber was made, in any pterosaur.
Maybe that's where the multiple naris comes in.>

  Except no one else has supported the multiple nares, and ANY nares could have
easily functioned this way, much less more than one. One large naris on either
side of the skull would have allowed for greater intake volume per second than
many tiny holes, and thus it would seem if the flesh could contain water volume
to allow sinkage, then one nares, in the antorbitonarial opening, would have
been better than many tiny nares further rostral in the skull.

  Another issue is that tidal waders tend to have retracted nares, not
rostrally situated ones, to allow breathing while probing. Having a long
probing snout with nares at the tip seems counterproductive to continued
survival. Kiwis, in having rostrally-situated nares, do not probe into media
where the probed material prevents breathing (litter and underbrush and loose
soil). Thus it is more likely tht a probing snout would have a
posteriorly-located naris, not an anteriorly-located one.

<Sixth, Q taking off from poling depth waters. Perhaps it never happened. Maybe
there were better ways, which I listed earlier, of avoiding bad guyz. It's
still worth throwing an idea out there, even if Jim thinks it's gutsy, and
especially if there are animators around who have to make such scripts
believable. We are in fantasyland much of the time with prehistoric animals.
We've all seen worse ideas make it into the lit.>

  And part of the task of paleobiology, as stated elsewhere by John Hutchinson,
is that it is the job of the paleobiologist not to suggest means, but reject
means. By finding out what these animals CAN'T do, we are more the scientist
leaving all other possibilities as what COULD be done. By analogy, tt is
possible to fly a feather and a barn door, but aviators have spent a century
figuring out what CAN'T fly (with some amusing -- and tragic -- results).

  Cheers,

Jaime A. Headden
http://bitestuff.blogspot.com/

"Innocent, unbiased observation is a myth." --- P.B. Medawar (1969)

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