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

[David Peters <davidpeters@att.net>]

Well said, Jaime.

That being said, I had the original in my hands also.

David


On Apr 22, 2009, at 5:45 PM, Jaime Headden wrote:

> 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.
>
> Cheers,
>
> Jaime A. Headden
>
> "Innocent, unbiased observation is a myth." --- P.B. Medawar (1969)
>
> "Human beings, who are almost unique in having the ability to learn  
> from the experience of others, are also remarkable for their  
> apparent disinclination to do so." --- Douglas Adams (Last Chance  
> to See)
>
> "Ever since man first left his cave and met a stranger with a  
> different language and a new way of looking at things, the human  
> race has had a dream: to kill him, so we don't have to learn his  
> language or his new way of looking at things." --- Zapp Brannigan  
> (Beast With a Billion Backs)
>
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David Peters
davidpeters@att.net