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Re: interesting Triassic stains (A BIT LONG)



What follows has not to be considered as a dismiss of David Peters ideas in general, but as aimed to point out some flaws in his intepretations of Eudimorphodon, possibly due, at least in my very humble opinion, to some weaknesses of the method:

At 23.29 24/02/03 -0600,     Richard W Travsky <rtravsky@uwyo.edu>     wrote:

Concerning a message by David Peters on stains in Eudimorphodon:
Ok, you got my curiousity going. I'd like to see tho not necessarily
correspond on it. Is there somewhere you could post a picture? Web site
or something?

everyone can see a picture of the specimen at this URL:

http://users.unimi.it/vertpal/galleriafossili/best-rettili/EUDIMORPHODON.htm

It's a bit a low resolution one but it works.

Concerning David Peters statements on Eudimorphodon I have to cast my doubts about some assumptions

In the recent past, I've been chided and ridiculed for "seeing things"
in the stains and impressions I find in scans of fossil pterosaur
pictures. Well, it's time to put the ole sore neck on the chopping block
again.
In the often-pictured holotype of Eudimorphodon ranzii there is a
wonderfully preserved skeleton on a slab and surrounding it are a number
of stains.
Absolutely not my intention to chop off your head David, but I recommend you to look carefully at the actual specimen. From its discovery onwards it has loaded with various kinds of glue (arabic, that old one to stick stamps on envelopes and figurines on albums), paraloid (a resin), and the hell knows what else. Thus it has stains but sincerely I am dubious about their nature. In addition the matrix itself has different proportions between organic matter and marly limestone from one spot to another....
In further addition a rather old fashioned mechanical preparation with a vidian nail (that one for old record players, when music scratched, he he) has possibly erased anything that was not bone....thus the specimen is not exactly untouched..


4. a larnyx

5. a propatagium

6. two narrow-chord wings, both attached to the elbows. One clearly
crosses the sternal complex. The trailing edge looks like a crack.

Indeed, it has been considered as a crack so far.


I didn't see all the other stuff on the specimen; Fabio Dalla Vecchia looked at it much carefully than I did, but seemingly he also missed it. Fabio where are you? There is nothing in your in your PhD dissertation about this stuff?


8. what Wild (1978) described as the prepubis appears to be the broken
open head of the femur, so now the femur is no longer the "too short"
anomaly it was. The "head " of the femur has only a small articular bump
without a constricted neck.
9. the base of the coracoid expands into a delta ventrally.
10.a complete pelvis
11. and the real prepubis.

I have no problems to admit that previous authors may well have misintepreted something here and there, it happens frequently, but I feel strange that both Wild and Fabio (this latter guy is particularly nitpicking and nearly nothing escapes from his observations) and, on a second issue (I did not work on it) myself, didn't realize such obvious errors in Wild paper. Also Kevin Padian saw the specimens.


Some final word of wisdom, if I can dare:
I tried to work/play with photos and various methods with PC, as you also suggested, partly for interest and partly for fun, but I soon realized that shadows cracks and matrix artifacts often play nasty tricks: One can eventually do something with photos only if the real specimen is at hand for continuos cross-check. Otherwise it is easy to see things that aren't there or are different. And if you have the specimen at hand working with photos may eventually lose some significance.
All the best,


                                        Silvio Renesto


_ "When they hear of the Way, The highest minds hurry up to practice it; The average minds think about it They sometimes feel it real and sometimes not; The lowest minds laugh at it. If they did not laugh at it, It would not be the Way."

                                (Lao Tzu)


Silvio Renesto

Facoltà di Scienze
Università degli Studi dell'Insubria
Via Dunant 3
Varese
Italy
temporarily:
phone +39-02-50315511
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e-mail:  renesto@mailserver.unimi.it
        Silvio.Renesto@unimi.it
have a look at our Triassic  website at
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