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

Re: pterosaur take-off analog



As Jim already indicated, we have indeed looked at a range of wind conditions for both quad and biped launch situations. Only very special gust scenarios will launch mid-size pterosaurs, and it is almost impossible to launch a large one by gusts alone (easy to lift it off the substrate very briefly, but that's not sustainable). One thing to note here is that while some birds do get the benefit of nice, gusty environments, they are all able to launch under their own power from whatever sort of substrate/habitat they utilize. So, while the albatrosses do use gusts when available, they can running launch (as you indicated). Because mid to large pterodactyloids could not biped launch effectively without special conditions, it is very, very unlikely that they were biped launchers - if they were, we would expect them to be able to manage it without gusts, even though they might use them when possible. And, in fact, gust-assisted biped launches are still not feasible for most species. Gusts do help the quad launch, however.

--Mike


Michael Habib
Assistant Professor of Biology
Chatham University
Woodland Road, Pittsburgh PA  15232
Buhl Hall, Room 226A
mhabib@chatham.edu
(443) 280-0181



On Oct 5, 2009, at 8:40 AM, David Peters wrote:

Last night Animal Planet - Wild Pacific - Eat or Be Eaten, fledgling albatrosses were shown getting hungry on their small beach environs, parents absent. Most were spreading their wings in the elevated configuration. Some ventured into shallow waters to float while doing the same thing. There they became shark bait, but that's not the point here. The wind, as it picked up, gently carried them aloft, out of harm's way and off on their first trans-oceanic voyages. Sure there were some running take-offs, but heading into the wind made everything much easier. They were light on their feet and flapping was not really much of an issue.

Pterosaur wings were like those of sailplanes (when properly reconstructed). Maybe calculations involving take-offs should be modified to reflect different wind conditions. The above scenario seemed especially appropriate for certain derived ornithocheirids, which, by all indications, had the smallest pelves and feet of all. Certainly smaller pteros were big on flapping and there would have been a spectrum of abilities in between the smallest and largest.

David Peters
St. Louis