High horse stabilised

[Unwin <h0662eka@rz.hu-berlin.de>]

Offstage: 'Leave my high horse in the stable ostler, its got a bit of a 
headache.' (1) 

(numbers in brackets refer to textual references - see notes at end of message) 


In his previous posting Peters wrote:

<At this point I am convinced that you have not read my papers or emails.I 
reiterate. _All _ pterosaurs were capable of both bipedal and
quadrupedal locomotion. In certain taxa, the preferred method was one or
the other depending on morphology. In most ,their standing poses need
not shift at all moving from one form to another. All they had to do was
to drop or raise the elbows. IMHO, it was _that_ easy.>

As I have noted in previous emails, and various publications, in my opinion 
pterosaurs were quadrupedal plantigrades, but could probably manage brief 
moments of bipedality (wind notwithstanding). Peters' statement on this issue 
seems to be at least partially consistent with this idea, except that Peters 
implies that certain unspecified taxa spent more time as bipeds than I think is 
likely. But, as I have pointed out, ad nauseam, fossil evidence (tracks, 
skeletal anatomy and biomechanics, computer models, soft tissue structures) do 
not support the idea of protracted bipedality. Until some clear evidence can be 
adduced for persistent bipedality it will remain a question of faith rather 
than fact. 


Later Peters wrote:

"Why, you're not a wizard at all!" (2)

Well, I recently tried carving a zig-zag scar on my forehead (3) and waving a 
wand (actually it was a spare chop stick) in the direction of the kitchen while 
incanting 'dirty washingupus begone', but the only result was that my wife told 
me to stop pratting about (4) and get my arms in the sink. So, I'm a muggle (3) 
born and bred it would seem (just wait till I get a real wand!). 


Then Peters wrote:
<At this juncture I am convinced that you have not read Bennett's paper,
either. Although he did show Nyctosaurus in a quadrupedal pose he wrote:
"This would make quadrupedal locomotion difficult.?At approximately 60º
above horizontal, the animals would be essentially in the upright
bipedal posture proposed by Bennett (1990, 1991, in press) and the
center of gravity would be over the hindlimbs. At this point, the animal
might as well pick up its forelimbs, fold them compactly, and walk
bipedally.">

However, from the now innumerable number of times that I have written 'in my 
opinion pterosaurs were quadrupedal' one might deduce that I do not entirely 
agree with Bennetts interpretation of Nyctosaurus' terrestrial ability. I 
suspect the latter was almost always quadrupedal, and that it could move around 
quite effectively in the pose shown in Bennetts reconstruction, but that it was 
highly adapted to a flying life style (albatross or frigate bird-like) and 
consequently spent little time on the ground. Indeed, pretty much the same can 
probably be said for all ornithocheiroids (Istiodactylus, Ornithocheiridae, 
Pteranodontidae and Nyctosaurus)



In my previous post I stated:

>>Unfortunately, it would appear that pterosaurs were not familiar with
Peters (2000) hinge line analysis and, as the tracks show, doggedly
continued to proceed in plantigrade fashion.<<

To which Peters replied: 

>>Didn't read _that_ paper either, did you?  If you did, you'd already
know that hinge line analysis also indicates plantigrady in certain
forms, irrespective of tracks.<<

Having read the 'hinge line' paper on several occasions I have concluded that 
the 'hinge line analysis', as described by Peters, reveals nothing about the 
way feet function. It is purely a graphical device that, like the computer 
enhancement of photos discussed by Bennett in his website, illustrates things 
that are not actually there. Moreover, this 'technique' directly conflicts with 
the results of various recent studies of skeletal anatomy and functional 
morphology, and, perhaps even more importantly, with the track record, further 
emphasising its problematic nature. 



Later Peters stated:

<Evidently you don't read my emails to others, either. [Ooops, that's a
good thing!] During private correspondence with Sarah, she mentioned
that she was not familiar with my hinge line work, only that of Clark.
Otherwise I haven't seen Sarah's studies. If, since reading my work in
the meantime she rejects it, then that's another issue altogether. >

I do not understand what point is being made here. However, I do stand by my 
original statement that to comment adversely on Sangsters studies, especially 
in those cases where the individual is unfamiliar with her work (and makes 
public statements to that effect) is wholly inappropriate. 


Subsequently, Peters made various statements in his latest post regarding 
attempts to discuss his interpretations of skeletal anatomy using computer 
enhancement of published photographs: 

>Not if to do so would have violated pre-publishing limitations. That's
why they have this thing called "private correspondence." And I look
forward to yours, whenever it may come.<

>The issue here is prior consent of copyrighted materials. Chris could
have said, "Listen Dave, let's have a public airing of this issue. Mind
if I create a website based on your work?" He didn't. <


It seems to me that these and previous posts by Peters contain highly 
contradictory statements. Peters started the thread with his Nov 26 post on 
'Road kills' which made it quite clear that he wanted to discuss, in the public 
arena of the DML, the images he has been producing using computer enhancement 
of published photographs. So why, according to Peters, should Bennett have said 
'let's have a public airing of this issue' when this had already been requested 
by Peters? 


Subsequently Peters stated:

 <'I'm proud of my work and love to discuss it'.> 

and then: 

<'From what I could see Chris edited the work by removing the color identifying 
the bone shapes. That's not right either. I'm still eager to see the opposing 
evidence.'> 

How the heck can we see the work, and discuss it, and present opposing evidence 
if, when someone puts up a website to do exactly that (in this case Bennett), 
they are ordered to take it down again? Moreover, it is evident from Peters 
earlier post (Dec. 3rd: Pterosaur scans: addendum, 'I may use those images in 
future submissions to scientific journals') that the figures analysed by 
Bennett in his web site are not about to be published, or are even submitted 
for publication, and thus quite free from any prepublication embargo. I submit 
that the reason Peters does not want us to see these images, and their analysis 
by Bennett, is because they show that his technique mistakenly identifies 
irregularities on the sediment surface as impressions of bones, but fails to 
identify real bones even when they are easily visible to the naked eye. So, to 
reiterate, Bennett has shown that the technique is fundamentally flawed, 
consequently the images that it produces and any conclusions base!
d on them should be rejected. And contra Peters previous post, its not a 
question of which pixel is right and which is wrong. If viewers know that parts 
of an illustration are incorrect, how are they to know which parts are right 
and which are wrong? Unless of course they go and check the original specimen, 
which I believe answers Peters first post on this subject. 

Since it would seem that the majority of list readers will not be allowed to 
see the images that we have been invited to discuss (although as I write they 
are still there on: http://www.bridgeport.edu/~cbennett/Critique.html), might I 
suggest a test any list reader can do the next time they get access to a 
Solnhofen pterosaur (or any other flattened specimen for that matter). 
Illuminate the specimen with low angled lighting (you have to do this to see 
details and this is how most of the good photos of Solnhofen pterosaurs in 
Wellnhofers (1991) encyclopaedia were produced). Now, slowly rotate the slab 
and watch how different 'impressions' come and go, and change shape, as surface 
irregularities assume different positions with regard to the light source. 
Then, decide from which of these positions you would prefer to illustrate the 
specimen. And don't forget, while sketching those surface irregularities, you 
can actually choose which orientation of the slab you prefer: those wo!
rking from published photos don'teven have this luxury.  

OK, time for me to get my arms in the sink. 

Tschuessi

Dave 



PS. My high horse says his headache is much better now, thank you, but, if I am 
going to go supernova please could I not do it in his stable because it is made 
of wood and contains a lot of hay. Oh...sorry... and contains a lot of HIS hay. 

PPS. High horse has also asked if he can be excused from the public lynching 
because he doesn't like the sight of blood. I suggested that perhaps he was 
getting confused with guillotines to which he replied 'See, I told those guys 
they were doing it wrong'. 


Textual explanations (as kindly requested by Silvio Renesto).

(1) 'High horse'. A figure of speech; to get on ones high horse means to 
pontificate about something (usually that one is rather obsessive about), often 
with the effect of 'talking down' to the object of ones attentions (obviously a 
high horse helps in this respect). An ostler is someone who looks after horses. 

(2) '...ot a wizard'. Refers to that strange and rather creepy film The Wizard 
of Oz, rather than that excellent fellow Mr Ozzy Osbourne. 

(3) A reference to Rowlings' Harry Potter. A muggle is an ordinary member of 
the public without any magical powers. Apparently I belong in this group (sob). 
Incidentally, anyone who has not seen the latest film, but plans to go, stay 
until the very end of the credits - really, its worth it! 

(4) 'Pratting about', English vernacular, fooling around when one should be 
doing something more useful. Which reminds me...


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Institut fur Palaontologie, MUSEUM FUR NATURKUNDE 
Zentralinstitut der Humboldt-Universitat zu Berlin
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Email: david.unwin@rz.hu-berlin.de

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