FW: Yet more on dinosaur quad climbers

[Jason Brougham <jaseb@amnh.org>]

Mike, Do you think that the feathers of Anchiornis, as described in Longrich et 
al. (2012), may be good candidates for an 'almost' flight feather, or more 
likely to be a degenerate flight feather?

The authors here suggested that the remiges may have been less stiff 
individually, but there were more layers in the wing producing, in essence, a 
thatched airfoil.

From: Mike Habib <biologyinmotion@gmail.com>

Of course.  And the immediate precursor to flight feathers was presumably an 
"almost" flight feather - likely vaned, interlocking, and relatively large - 
but just short of the morphology required for aerial locomotion.  This is what 
I meant by a "precursor"
 in this context.  Some maniraptorans had small wings, but were not aerial 
animals in the strict sense.  Their near-flight grade feathers therefore 
presumably evolved in a non-aerial context.  This could still be a 
lift-dominated context, a drag-dominated context,
 or a non-aerodynamic context (such as display or protection).  It could also 
be a combination of any of those three. 

Regardless, there needs to be a mechanism to move from a relatively 
non-aerodynamically active feather to a highly aerodynamically active feather, 
and that is going to necessitate some morphology that is very nearly "good 
enough" for flight, but not quite. 
 Since an animal with such feathers wasn't flying, the feathers have to get at 
least that far without flight as a factor.



--Mike 





Michael Habib

Assistant Professor of Cell and Neurobiology

Keck School of Medicine of USC

University of Southern California

Bishop Research Building; Room 403

1333 San Pablo Street, Los Angeles 90089-9112

biologyinmotion@gmail.com

(443) 280-0181