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Re: Quetzalcoatlus could not jump into the air

Dumb question:  This abstract assumes a downstroke would have been necessary 
for takeoff.  Is it possible that under the right conditions simply opening the 
wings at the right angle and facing into the wind could have gotten the animal 
high enough for a full wingflap without much muscular effort?

Ronald Orenstein
1825 Shady Creek Court
Mississauga, ON L5L 3W2

From: Ben Creisler <bcreisler@gmail.com>
To: dinosaur@usc.edu 
Sent: Thursday, November 8, 2012 11:53:30 AM
Subject: Quetzalcoatlus could not jump into the air

From: Ben Creisler

A talk at the GSA meeting and a new story:


CHATTERJEE, Sankar, Geosciences, Texas Tech University, 3301 4th
Street, Lubbock, TX 79409-3191, ALEXANDER, David E., Ecology &
Evolutionary Biology, University of Kansas, 2041 Haworth Hall, 1200
Sunnyside Avenue, Lawrence, KS 66045, and TEMPLIN, R. Jack, 2212 Aster
Street, Ottawa, ON K1H 6R6, Canada, jtemplin@rogers.ca
Large pterosaurs could takeoff from an elevated perch by diving into
the air to initiate flight, but to take off from level ground was
arduous. Our estimated mass of the giant Quetzalcoatlas from the Late
Cretaceous Big Bend National Park of Texas is about 70 kg, which is
close to the theoretical upper mass limit for a flying animal.
Quetzalcoatlus could run bipedally downhill to pick up flying speed, a
technique used by albatrosses and hang glider pilots. It has been
proposed recently that Quetzalcoatlus with a new calibrated mass of
250 kg was capable of initiating flight directly from the ground using
forelimbs as a catapult similar to the style of common vampire bat (~
25 g). One issue is scaling. What is possible for a lightweight bat
appears impossible for a 10,000 times heavier pterodactyloid, which,
due to surface-to-volume ratios, will have approximately 0.0
r unit mass of the bat. Another is the height
achieved by such a “pole-vault:” the maximum ballistic jump height of
2 to 3 meters would not be high enough to allow a significant
downstroke, where most lift and thrust is produced. With a wingspan of
10.4 m, Quetzalcoatlus would not have been able to flap vigorously for
lift generation from such a jump without smashing its delicate wings
on the ground. Moreover, the animal would need about 2440 watts to fly
level after jumping; the estimated maximum mechanical power available,
however, even with a few seconds of maximal anaerobic muscle
contraction, was approximately 1600 W, far below the flying speed that
would result in crash landing. Indeed, the body mass of 250 kg itself
appears to be largely overestimated, as powered flight and ground
takeoff seem unlikely for an animal that heavy.

2012 GSA Annual Meeting in Charlotte


news story:

http://news.discovery.com/animals/flying-dinosaur-pterodactyl-121108.html ;