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

I would like to close my current discussion on this topic with my opinion on my 
use of photographs:

  Photographs are photographs, and they represent a finite level of detail no 
machine or technology can increase (not without the original negatives, and 
certainly not without considering the resolution the negatives are produced at 
themselves) and when read on a digital machine, everything is rendered in 
pixels, which REALLY restricts artifacts. Whereas before you have ink/laser 
artefacts that reduce fineness of detail at the microscopic level in which some 
of these photos must be read (as a book, in cases), on the computer you have to 
see that a pixel contains no subpixels of information that can be gleaned, 
decoded, aliased, or whatever, no matter the technology of the tool. When you 
have a digital reproduction of a physical artefact like a photo in which the 
lighting is skewed, and the resolution weak, you are introducting layers of 
problems in interpretation into your image and what ever you want to get out of 
that image must come according to the restrictions therein. So much is not 
visible in a photograph that the original is ALWAYS superior, and even a cast 
is dependant on the fineness of the casting material (in two degrees, the 
material used to make the negative from the original, and the material used to 
create the positive copy that is the cast itself).

  This is the world I enter when I use ANY photographic sources to produce any 
skeletal, and it often means a lot of guesswork (skull bone shapes, positions, 
vertebral shapes, positions of apophyses on vertebrae, etc.) which influences 
the final product (if I can get that far) to the point that it is not possible 
to make a perfect skeletal, a perfect skull image, or even assure yourself of 
the detail to which you would like, even if it's critical that you have that 
detail. I had the opportunity to examine (briefly) a cast of the holotype of 
*Longisquama insignis*, and it was this brief episode that has cemented my 
understanding of the slab and all that it can reveal: 

  There are holes in the slab created by imperfect splitting into part and 
counterpart, where chunks of material were separated from the slab everyone 
sees now, and there are portions of the slab which are irregular unworked 
surface but show dips, ridges, and rolling hillside that would remind anyone of 
the lovely nonflat countryside in northern England and Scotland. This slab does 
not, and cannot, preserve material hidden to the untrained eye or photograph at 
much of any lightning because, in most cases, the slab isn't there to expose 
this information. The animal is extremely small, although not as small as some 
intriguing fossils (an entire conodont apparatus can fit on the head of a pin 
... I sympathize with the people who prepare and investigate this material 
first hand), and even the resolution of the cast shows that there is 
unconformed crushing and smushing in the skull and shoulder, and in fact any 
portion of the skeleton where a bunch of bones are layered atop one another. 
The finest and most perfect detail in the slab are in fact located on the 
structures that radiate outward from dorsal to the spine, attached or not, and 
this detail is still lower than the fine details of sutures and contacts among 
cranial bones, and much less detailed than the fineness of the dentition, which 
as far as I can tell are just slightly curved cones.

  My skeletal of *Longisquama* is, was, and will continue to be nothing but 
rampant speculation compared to the detail I could glean from a 10 foot long 
mount of GIN 100/42, currently referred to *Citipati* sp. and one of my 
favorite fossils ever, and certainly deserving of its own specific monicker 
when it is fully described.


Jaime A. Headden

"Innocent, unbiased observation is a myth." --- P.B. Medawar (1969)

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