Re: back to pteros, [yada, yada]

[David Peters <davidrpeters@earthlink.net>]

>     No, I do agree that my tone is harshly critical in this case. Requests for
> blind tests and objective reasoning in the application of the technique have
> been largely put aside based on my knowledge of the situation.

> If there have
> been such objective tests, first hand observations, better photos, blind
> studies, etc., to support the conclusions, then I will be more than happy to
> shift back into my original supporive stance for the technique.

>>>>>> Jaime, you came up with the perfect blind test when you mentioned the
'headless' Pterodaustro juvenile. My recovery of said head and cervical series
matched in detail that offered by Chiappe and his egg + embryo. The future will
either bring bring validity or refutation to the other identities I propose.
Either way, we'll get closer to the truth, which is the whole point of science.

>
>
> <Every observational technique is 'highly' subjective. Every jury and judge is
> 'highly' subjective. The Photoshop technique simply offers a way to send
> extremely precise tracings on top of layers of photography to others for
> confirmation.>
>
>   And the drawing of lines on a slab perceiving that the completely prepared
> matrix in a chalk bedding plane described "hidden" bones? This was the case 
> for
> another published objection to this technique on the basis of *Nyctosaurus* 
> sp.
> Since the slab itself was prepared down to recover bones within the chalk, it
> is impossible for impressions of bones or tissues to be preserved out of the
> bedding plane recovered.

>>>>>> Time will tell. When other skeletons arise we can compare them to the
ephemeral ones.

>   Yes, if I find a crack in the bone and the bone is flaked out (like what
> happens when bone is either eroded or removed during splitting of a slab) it
> will look like a "naris" too. The problem with this theory is one of
> identification and corroboration independantly. Which hasn't happened.

>>>>>>> Neither has anyone 'taken on' the prolacertiform theory, or the narrow
wing chord observation. In my opinion, the number of theoretical pterosaur 
papers
(save the disaster by Chatterjee) has plummeted recently. In other words, blame
others for the lack of corroboration or argument.


> Indeed,
> the positions of the nasal bone itself, and a developmental series in
> pterosaurs offers evidence for a particular fusion of the external naris with
> the antorbital fenestra, the "classic" model, which, while "classic" and
> therefore "wrong", objections have to go through as much scientific rigor to
> overturn it.

>>>>>> I disagree and I show numerous examples at pterosaurinfo.com. Please send
examples of the classic model.


> Using cracks and holes that are present all over the skulls of
> most pterosaurs preserved in slabs to find these special ones and then to
> identify them as external nares is _a priori_ observation. For example, what
> stops these "holes" from being foramina or subnarial fenestrae?

>>> a jugal below and a nasal above, as in all pterosaurs.


> Indeed, one
> theory about beaked animals is that they should have many foramina on the 
> bones
> supporting the rhamphothecal sheath for the purpose of ennvervation. Instead,
> they are "the naris 'that shouldn't be there'."

>>>>> show me sheath extended back to the AOF.

>
>
>   In response to Peters, I can corroborate seeing these features, but I do
> think they are artifacts. Not because I "believe" in the confluent nares/aof
> theory, but because I observe the irregularity of the features, the tiny size
> of them, and the need for a nasopharyngeal passage of greater opening than 
> tiny
> slits in a skull that large which, for an active "warmblooded" animal, will
> need to be VERY large.

>>>>>>  Look at pelicans, cormorants and other sea birds. Tiny to absent nares.

>
>   It seems like one's looking objectively, thinking scientifically, but this 
> is
> just a self-fulfilling prophecy: the data will fit what we want it to because
> we are making it as we go. As Freud said, sometimes a cigar is just a cigar;
> or, in other words, some times a crack in the rostrum of a pterosaur is just a
> crack in the rostrum of a pterosaur.

>>>>>> Funny thing is, these cloud-like ephemera fit the phylogenetic puzzle. 
>>>>>> One
can trace the development through many specimens.

>
>
> <This same technique resulted in the finding of a skull in a specimen of
> juvenile *Pterodaustro* which, according to the people who have studied it
> first hand, doesn't exist.>
>
>   See above. I looked for this, curious if after I wrote what I did I had been
> confused and Dave had another specimen in mind. I opened up Cordniu and
> Chiapppe and looked at the specimen in question. Every single bone is 
> preserved
> in nearly articulated glory except for the neck (broken and disjointed, but I
> doubt I will find missing vertebrae to fill the gaps [note: Dave has not
> suggested he has done this, I am doing this to consider previous examples of
> filling empty space with bones]), and the skull is not present; you would 
> think
> so well ossified, as is consistent among vertebrates, that the skull would
> ossify if it stayed intact. I find the slab on the other side of the skeleton
> just as consistent with this finding as the region where Dave finds the skull.

>>>>> Woulds and Shoulds are to be avoided. I'll try to post before and after
images today of the juvenile Pterodaustro to clarify issues. I also find wing
claws, an extended tail and manual digit V.

>
>
>   Psychology and neurobiology teach us that when we try to look at something
> where the image is fuzzy or unclear, our eyes will fill in the missing details
> and our minds will try to fit something familiar into the gaps. This will give
> us a picture in our heads not entirely consistent with the actual object we
> perceive.

>>>>>> Except that this time it is entirely consistent with other specimens.

>
>
>   Such subtleties are the very basis of the contention. A missing flake of 
> bone
> in the snout of a pterosaur is not the same as a whole skeleton of
> *Longisquama* on the holotype slab as Dave contends. Dave has argued from a
> developmental standpoint that the bones of many babies and even "adults" are
> present, form impressions, or never ossify, contrary to any developmental 
> model
> thus far known. He has not used any independant observations for what would be
> an extremely important discovery to support this, but contends the impressions
> are, by themselves, sufficient to support his case.

I am still waiting, as you are, for an independent observation.

>
>   Chris is also further working on the very taxa he published on which Dave
> provided contradictory data for: A complete *Anurognathus* specimen, 
> incomplete
> KJ1 and KJ2 skeletons of *Nyctosaurus* sp., *Pterodactylus* growth series and
> coincident species identifications, etc.

>>>>>That's good. If Chris comes up with better data, observations, etc. then
we'll see some progress.

> Especially given arguments of how much one can interpret a
> few pixels on a digitized photograph.

>>>>>> This few pixels business occurs on occasion. Otherwise I'm recovering
entire bones and fenestra from high-resolution photographs.

> This is another reason why Chris Bennett
> has argued that to substantiate these claims, it is required to see the
> specimens themselves and show them in detail.

>>>>>> Ironically Chris provides at his website a great closeup of AMNH 1942 in
which the large naris is very clearly set off from the AOF once the broken 
pieces
are repaired and replaced. I'll be posting it asap too.

> Photographs will not do, and may
> be used to illustrate the point, but are not evidence themselves, especially
> given the distance taken, the light level and angle, and the detail of the
> bones themselves which may, as Gerald Mayr has found out, require preparation
> to see clearly using chemical coats.

>>>>> Then we are left with the 'word' of the observer.


> The bone and matrix are
> the same general colors, and are not distinct; highly detailed color photos of
> the material I was provided only prove this point. Differentiation becomes
> dangerously subjective and requiring what one thinks it _should_ look like.

>>>>> And that's the "art" of paleontology. Lots of mistakes are made. Others 
>>>>> come
along and fix them. Sometimes ridiculous claims, like Beebe's 4-winged proto 
bird,
become reality.

>
>
>   Narrow-chord has been proposed in Unwin and Bakhurina, who, although they
> linked the cheiropatagium to the ankles, draw the chord toward the arm far 
> more
> narrowly than the classic model, which is drawn by Wellnhofer and was first
> illustrated for *Sordes* by Sharov himself. Padian, especially in his popular
> article in _Natural History_, espoused the narrow-chord model.

>>>>>>> If that's what you call a narrow chord... now I understand. They're 
>>>>>>> still
not narrow enough in my paper because they tie into the hind limbs or hips.

>   ...
>
>   Dave, if my tone sounds unwarrantly critical, it's not that I don't like 
> you;
> you are an awesome man and I am glad to have met you. I hope I do not have to
> say this about anyone anymore, since as a scientist and a student, I know I
> will never learn all I can, but will make an effort of it. Fighting for rigor
> in scientific practice when I see a need will always be a driving force in my
> social interactions, I fear.

>>>>>  It might be better yet if you were to say, "show me, I want to learn." 
>>>>> But
be forewarned, I do make mistakes. But the treasures found between the mistakes
seem to make the occasional embarassments less painful.

David Peters
St. Louis