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Use of Tail and Legs in Flapping in Bats
I'm surprised this wasn't mentioned, in all the brouhaha surrounding
"Toroceratops."
http://10.1371/journal.pone.0032074
Adams, R. A., Snode, E. R. & Shaw, J. B. 2012. Flapping tail membrane in bats
produces potentially important thrust during horizontal takeoffs and very slow
flight. PLoS ONE 7(2):e32074.
Abstract:
Historically, studies concerning bat flight have focused primarily on the
wings. By analyzing high-speed video taken on 48 individuals of five species of
vespertilionid bats, we show that the capacity to flap the tail-membrane
(uropatagium) in order to generate thrust and lift during takeoffs and
minimal-speed flight (<1 m s−1) was largely underestimated. Indeed, bats
flapped the tail-membrane by extensive dorso-ventral fanning motions covering
as much as 135 degrees of arc consistent with thrust generation by air
displacement. The degree of dorsal extension of the tail-membrane, and thus the
potential amount of thrust generated during platform launches, was
significantly correlated with body mass (P = 0.02). Adduction of the hind limbs
during upstrokes collapsed the tail-membrane thereby reducing its surface area
and minimizing negative lift forces. Abduction of the hind limbs during the
downstroke fully expanded the tail-membrane as it was swept ventrally. The
flapping kinematics of the tail-membrane is thus consistent with expectations
for an airfoil. Timing offsets between the wings and tail-membrane during
downstrokes was as much as 50%, suggesting that the tail-membrane was providing
thrust and perhaps lift when the wings were retracting through the upstoke
phase of the wing-beat cycle. The extent to which the tail-membrane was used
during takeoffs differed significantly among four vespertilionid species (P =
0.01) and aligned with predictions derived from bat ecomorphology. The
extensive fanning motion of the tail membrane by vespertilionid bats has not
been reported for other flying vertebrates.
Cheers,
Jaime A. Headden
The Bite Stuff (site v2)
http://qilong.wordpress.com/
"Innocent, unbiased observation is a myth." --- P.B. Medawar (1969)
"Ever since man first left his cave and met a stranger with a
different language and a new way of looking at things, the human race
has had a dream: to kill him, so we don't have to learn his language or
his new way of looking at things." --- Zapp Brannigan (Beast With a Billion
Backs)