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Pterosaur take-off visualization aid



We had a lot of discussion a few weeks ago about how big heavy pterosaurs
moved on the ground and how they got off the ground: one point emphasized
(by some participants) was the likelihood that the initial takeoff would be
a jump powered by the forelimbs.  This I found hard to visualize.  (That's
not scepticism, just autobiography: I found it hard to VISUALIZE.)

The current top story on Carl Zimmer's "The Loom" website is about bats.  I
know that bats and pterosaurs differ in lots of ways.  One You-tube snippet
on it is (top view and side view) of a vampire bat running.  I know running
and takeoff are not the same thing.  BUT, just as an aid to the imagination,
look at it.  Bats resemble pterosaurs in having more powerful forelimbs than
hind limbs, so it is not TOO surprising that the forelimbs in the running
vampire bat look as if they are doing more of the work than the hind limbs.
(The effective length of the forelimbs in terrestrial locomotion is also
greater than that of the hindlimbs: the bat's back, as it runs, is at an
angle to the ground that would do a Chalicothere proud.)  The airborn (all
four feet off the ground) phase of the run is initiated by a thrust from the
forelimbs.

I know bats are unlike pterosaurs in ever so many ways, but maybe they
slightly resemble them in limb proportions and comparative power of pectoral
versus pelvic musculature.  Just as an aid to the imagination, not making
any claims that it proves anything... I think it's a fun clip to watch.

Allen Hazen
Philosophy (PASI)
University of Melbourne