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Re: Did dinosaur wings evolve for breeding display?
Mark Hallet wrote: "If wings evolved primarily as a display device for
visual enhancement in breeding, why do we see already functional
aerodynamic structuring (i.e., unequal vane proportions) in the wing
feathers of known flying dromaeosaurs?<<
And Roberto Takata responded: "What is the phylogenetic position of
Caudipteryx? A secondarily flightless oviraptorosauria?"
As I've pointed out before "aerodynamic" is not synonymous with
"flight" or "gliding". The spoilers in race cars are aerodynamic.
Reducing drag is as well. Most robust phylogenetic studies recover
oviraptors sufficiently known fliers that it appears unlikely that they
are secondarily flightless (even if deinonychosaurs...which I doubt).
A large problem with the whole discussion is the very concept of "wing"
here. We know of coelurosaurs with elongated but non-branching
filaments on their arms, we know of coelurosaurs with apparently
branching but aren't true remiges, we know of basal maniraptorans with
non-assymetrical remiges, and several species for which their are
assymetrical remiges but legitimate debates about their flight ability
(and/or lack thereof). Finally there is a large and very succesful
group of flying maniraptorans that bear assymetrical remiges.
Which ones are the "wings" we are talking about?
If the origin of "wings" involves elongation of filaments it seems
perfectly reasonable to think that sexual selection was involved. If
the question is how do we get from unbranching to branching filaments,
it's plausible but seems less likely that sexual selection was the
culprit. If the origin of "wings" pertains to the derivation of
remiges from more simple branching filaments, it seems unlikely that
this happened outside of selection that involved aerodynamics (thought
not necessarily gliding or flight), and in the case of assymetrical
remiges it's almost beyond dispute that aerodynamic forces rather than
mate selection were the driving force (but conceivably still not
Of course, all of these things happened before you get to an
Archaeopteryx-grade maniraptoran, yet there are so many important
changes to the manus, to inboard feather distribution, to pectoral
girdle and glenoid morphology, and to alular evolution that you could
be forgiven for asking how the avian wing evolved after the
Archaeopteryx stage of avialan evolution, and breeding display was
probably at most a minor factor here.
Sorry to make this complex, but like Einstein said: "Make things as
simple as possible, but not more." Over-simplification obfuscates the
Wyoming Dinosaur Center
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Cell: (307) 921-8333
From: Roberto Takata <firstname.lastname@example.org>
Cc: email@example.com; firstname.lastname@example.org
Sent: Wed, 15 Apr 2009 2:28 pm
Subject: Re: Did dinosaur wings evolve for breeding display?
On Wed, Apr 15, 2009 at 4:17 PM, Mark Hallett <email@example.com>