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Re: Archaeopteryx flight

At 05:49 PM 10/20/2005 -0400, Patrick Norton wrote:
Jon Barber wrote (in part):

D) It lacked an alula, which assists in low-speed flight and maneuverability control.<

It's been my hypothesis for a long time that the aerodynamic function of the alula could have been fulfilled by the exposed finger claws of early birds such as Archie (see my post from several years ago at http://dml.cmnh.org/2001Jan/msg00543.html). As I note in that post, other vertebrate flyers without feathers (bats and pterosaurs) have/had non-feathered leading edge protuberances (aka, claws) in approximately the same leading edge location. It's my belief that these did/do function like an alula. This could be tested empirically, but I haven't done it, and neither has anyone else that I know of. Without testing this, it's premature to dismiss low-speed flight and maneuverability control simply because this protuberance wasn't comprised of feathers.

While the first digit may have functioned similarly to an alula, I suspect that it did a relatively poor job. The recent paper that describes Eoenantiornis points to the parallel evolutionary refinement of the alula in both the Enantiornithes and the Euornithes.