Re: Did dinosaur wings evolve for breeding display?/Longisquama

[Tim Williams <tijawi@yahoo.com>]

David Peters <davidpeters@att.net> wrote:


> The point is this: before you get big wings that do fly,
> whether pterosaur or chukar, first you start with small
> wings that do not fly. 


This is not mandatory for hypothetical incipient flight scenarios.  The WAIR 
hypothesis (which you are invoking) does say that the wings became larger as 
the forelimbs became more adept at executing aerodynamic motions.  

However, if the pre-flight stages (by which I mean pre-powered-flight stages) 
had a significant arboreal contribution ("trees-down"), and the pre-flight 
wings used for parachuting or gliding, then the wings might have been already 
quite large long before the advent of flight.  It all depends on how much 
"trees-down" or "ground-up" is in your hypothetical scenario.  (I'm not 
advocating a "trees-down" versus "ground-up" debate here; I'm just using the 
two sides of this outdated dichotomy as frames of reference.) 


> Good to hear you're not adverse to using photographs. Were
> you tracing with a pencil? Or using Photoshop? Photoshop
> provides an opportunity to virtually enlarge a photo to the
> size of a bedroom wall and to get rid of the halftone dots.


Oh no, not this Photoshop business again.  David M. said it best: <sigh>.


> On the contrary, it is what is is... or was! It _is_ to be
> trusted. We just have to reconstruct it after crushing.
> Careful attention to detail will unwrap the mystery so we
> can "uncrack the eggshell", so to speak. We can argue the
> details later, because several opinions will ensue,
> certainly. And if I'm wrong, or you're wrong on one or
> several points I would hope someone would point that out
> because we need to get this right!


Too often, _Longisquama_ has become a Rorschach test for people's pet views on 
evolution.  The BANDits have recruited _Longisquama_ in their fight against the 
dinosaur-bird link, even though there is no compelling evidence that the dorsal 
appendages of _Longisquama_ are homologous to feathers, or even that 
_Longisquama is an archosaur.  In fact, recent treatments of _Longisquama_ have 
refuted both assertions.


Now _Longisquama_ is being drawn into the orbit of pterosaur origins, on 
equally spurious grounds.


Cheers

Tim