[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]

RE: Pterosaur Takeoffs (Under-rated Bats)



Ben Creisler wrote:

<On pterosaur take-offs in the literature seems to be
overlooking some recent research on species of bats
that move about on the ground and can get into the air
directly from a flat surface without climbing to some
higher perch. Vampire bats can do this by leaping into
the air. I have not read the entire paper, but a
detailed abstract is viewable at
 
 http://www.biologist.com/JEB/200/23/jeb1149.html

 Also, the false vampire bat (Vampyrum spectrum) of
Central and South America hunts prey (rodents,
insects) on the ground and can get airborne with a hop
even though it is the largest bat in the New World,
with a wingspan of over 70 cm. I have seen footage of
this feat on the Discovery Channel but couldn't track
down a reference in the literature or find a website
that goes into any detail.
  
Any discussion of the take-off capabilities of
quadrupedal pterosaurs should consider how nimble bats
can be despite having back legs that are much less
developed than in pterosaurs. I would guess pterosaurs
had little problem hopping into the air. Whether they
could do it from water, of course, is a tricker
question. Although some bats catch fish with their
clawed feet, they can't get back in the air if they
land in the water. Some pterosaurs appear to have had
webbing between their hand fingers (mentioned in a
recent post from Darren Naish), which could have been
used for paddling if the function was not purely
aerodynamic.>

  Consider also that bats have, consistently, smaller
mass and mean weight than nearly any pterosaur you
could name. The smaller rhamphorhynchids and
dimorphodontids, such as *Anurognathus*, *Sordes*, and
*Batrachognathus*, are comparable in size to some
larger bats, so they are probably capable of this
feat, but definately not the larger forms, from
pterodactylid size and up, because to my knowledge, no
bird of that comparable mass (5ft+ wingspan) can do
this, and certainly the biggest pterosaurs
(pteranodontids and azhdarchids) could not just "jump
up into the air." Jim, you may correct me on some of
this, but from the little bit I've understood of
large-body aerodynamics and the ground-up flight
paradigm when dealing with dynamics for birds _or_
pterosaurs, I think there's some fair assumptions on
my part.

  Also, to my knowledge, albatrosses and condors make
a long run before jumping into the wind, often off a
steep incline, having wings that long and weight that
great.


=====
Jaime "James" A. Headden

"Come the path that leads us to our fortune."

Qilong---is temporarily out of service.
Check back soon.
__________________________________________________
Do You Yahoo!?
Bid and sell for free at http://auctions.yahoo.com