Re: Smart wings and the pterosaurs who had them

["James R. Cunningham" <jrccea@bellsouth.net>]

Dave and Witmer are right in that this is a good possibility re
floccular lobes, but one should also keep in mind that the round trip
from the wing membranes to the brain and back was sometimes a
considerable trip -- up to 17 meters from tip to brain and backin some
of the really big animals, and up to about 11 meters from the semi-span
center of lift to the brain and back. So the neural travel time for some
of the big guys was on the loose order of 1/8 second not counting
processing time required by the brain.  About the same as the
short-period pitch instability.  So if the big guys did too much fine
control in the brain, they'd be likely to induce PIO (pilot induced
oscillation), which is a quick way to cause a short and spectacular
flight.  Perhaps the highly developed brain was only intended to affect
the long-period instabilities?  With the short-period pitch instability
being handled interactively within the wing membrane itself?

You all may have already addressed this, but have you guys compared the
short-period instability to the neural travel time yet?

Also, re orientation of vestibular canals, note that pterosaurs spent
considerable time in flight, and one would presume that it was often and
perhaps usually, coordinated flight.  And in coordinated flight, the
apparent gravity vector often doesn't point toward the ground (or
anywhere near that direction).  So the vestibular orientation may also
be related to some need of coordinated flight rather than just head
positioning.  That should be taken into account when discussing head
orientation based on vestibular alignment in flying animals.  'Course,
it still needs to work on the ground too.  I'm not knocking the work,
just pointing out that the gravity vector ain't neccesarily pointed down
all the time.
JimC

MKIRKALDY@aol.com wrote:
> 
> Nature Feature of the Week is Dave Unwin's News and Views article:
> 
> "Smart-winged pterosaurs
> Why did ancient flying reptiles have so much processing power in the back of 
> their brain? To provide highly responsive flight control, is an answer to 
> emerge from an innovative analysis of pterosaur skulls."

Dave U wrote:


> Far more convincing, in my view, is Witmer and colleagues' proposal that the 
> floccular lobes were responsible for
> processing large volumes of sensory data generated by the wing membranes. 
> This is a plausible idea, because in
> other vertebrates the floccular lobes receive sensory inputs from skin and 
> muscles.