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Re: bipedality in pterosaurs



    Thanks to Jim Cunningham for pointing out:

    >Quetzalcoatlus species is extremely well preserved, and seemingly
quadrupedal.  Also, the
limited flexibility in the neck would make bipedality virtually impossible
due to cg
problems.  When assembled to the torso, the bones of the arm and leg
articulate to the
standard quadrupedal stance.  Also, Qn doesn't appear to have wing power
enough to launch
from a bipedal stance, but does have sufficient total power for quadrupedal
launch even
in a dead calm.<

    Jim has put more time and study into Quetzalcoatlus dynamics (from the
engineering standpoint) than anyone else of whom I have any knowledge.  I
think his conclusion(s) on terrestrial locomotion and launch of these
awe-inspiring Late Cretaceous pterosaurs, tend to be backed up by what I and
others have observed in the tracks and trackways (thus life records backing
up educated deductions based of bones) of Early Cretaceous pterosaurs,
including those of some rather large ones found here in Maryland: the manus
impressions are invaribly much deeper than the pes impressions.  It is as
though the center of gravity was very much forward, leaving me with a
feeling that any such trackmaker foolish enough attempting lifting the front
of the body upward in order to walk or sprint bipedally would betray having
badly failed Physics 1.1!  :)

    Further, I know of no pterosaur trackway wherein the manus impressions
eventually disappear and we are left with only pes impressions.  Then too,
all pterosaur pes impressions of which I am aware are plantigrade, i.e.,
with the metatarsals firmly planted on the ground.  Hardly a
running-sprinting-for-take-off type of situation, it seems.

    The continued speculation by some that pterosaurs might have become
bipedal before launch brings to mind a disasterous vision.  Background: Q.n.
had a wingspan that has been compared to that of the wonderful WWII
aircraft, the P-51 Mustang.  A P-51 taxies for take-off, then somehow and
foolishly lifts its body into a near-vertical position (disasterously
reducing lift), and splatters into the runway.

    O.K. the analogy is far, far from accurate, but it may not be entirely
inappropriate.

    Finally, IMHO, Kevin Padian may live to realize (if he hasn't already)
that his advocacy of bipedal pterosaur locomotion was a less than brilliant
part of his otherwise brilliant career.

    That just my personal opinion, of course.  But is one wishes to differ,
show me the trackway.  I will not hold my breath.

    Ray Stanford

All together now, to the tune of "Home, home on the range":

Oh give me a home, where the pterosaurs roam,
Where their trackways Kevin's error display,
And where seldom is heard, a bi-pedal pterosaur word,
Cause they walked in a quadra-pedal way!

    :)