Re: A problem of cartilage

["Kent A. Stevens" <kent@cs.uoregon.edu>]

Short answer:  No problem of cartrilage.  We provide for cartilage,  
as is apparent to even casual inspection.

Shorter answer:  just jump to the bottom of this post, where I quote  
from Joe's boss (click the link to hear) "I'm not arguing that with  
you"...

Short peek:  To confirm that I leave space between condyle and  
cotyle, I include below URL's to some representative ONP  
reconstructions (with the thumbnails and higher-resolution images  
paired below).  Note that I sometimes use transparency to clearly  
indicate that the condyle inserts only partly into the associated  
cotyle.

Brachiosaurus:

http://www.cs.uoregon.edu/~kent/DinoMorph/Brachiosaurus/SII- 
composite_th.jpg
http://www.cs.uoregon.edu/~kent/DinoMorph/Brachiosaurus/SII- 
composite.jpg

Three diplodocids (thumbnail below; higher resolution versions  
elsewhere on site):
http://www.cs.uoregon.edu/~kent/DinoMorph/Dicraeosaurus/ 
diplodocids_th.jpg

Mamenchisaurus:

http://www.cs.uoregon.edu/~kent/DinoMorph/Mamenchisaurus/images/ 
presacrals-th.jpg
http://www.cs.uoregon.edu/~kent/DinoMorph/Mamenchisaurus/images/ 
presacrals.jpg

Longer answer for GSP and others concerned about providing for  
cartilage in ONP reconstructions.

1) My ONP restorations do include spacing for substantial cartilage.   
The size of the gap is based on a substantial number of samples  
across actual sauropod necks that are in articulation in situ.  These  
include ventrally-exposed diplodocid neck series in relief up on the  
wall of DNM, and specimens such as DNM 28 (which is in storage on  
pallets at BYU) and the USNM Camarasaurus neck (also on pallet, only  
partly prepared), and Barosaurus lentus CM 11984 (likewise only  
partly prepared) and many others we have personally poured over and  
measured and photographed.  In all:  the central articulations are  
tightly spaced.  Obviously there is a gap, and I do not naively  
restore them as if there no intervertebral cartilage.  As my ONP  
digital photo-composites reconstructions clearly show, I provide for  
an appropriate intervertebral gap.

2) The gap between condyle and cotyle in articulated sauropod  
cervical series scales roughly proportionally to the condyle radius.

3) regarding the AMNH 5761 specimen,  the one where GSP says "Kent is  
still trying to argue that 5761 cervicals 11 & 12 are fused  
straight.  He is not going to win this one."  We should start off in  
heartfelt agreement with the observation that there is indeed a bit  
more (vertical) gap between the underlying foam cushion and the  
condyle of C11 than below the rim of the cotyle of C12 (which rests  
on the foam).  That's because the condyle is SMALLER in diameter than  
the cotyle.  Get it?  Let me go through the reasoning:  A) condyles  
fit inside cotyles, B) cotyles have an inside and an outside diameter  
(the rim has a thickness), C) the cotyle inside diameter is larger  
than the condyle diameter to provide for said cartilage.  Therefore,  
the cotyle outside diameter is necessarily a bit larger than the  
associated condyle diameter.  How much bigger?  Oh, about the amount  
the condyle of C11 is above the foam :)  I'm not arguing that with you.

4) We find that at most just a bit of the ball is visible between the  
raised ridge of the condyle (where the synovial capsule would have  
attached) and the posterior of the cotyle, at least for the caudal  
end of the cervical series.  Look at the illustration of Euhelopus  
(you can find it on my site) and see how tightly articulated the  
centra are preserved. Look at Janensch's illustration of the block  
containing C10-D2 of _Brachiosaurus brancai_ specimen SII:

http://www.cs.uoregon.edu/~kent/DinoMorph/Brachiosaurus/ 
cervicodorsalTransition_th.jpg
http://www.cs.uoregon.edu/~kent/DinoMorph/Brachiosaurus/ 
cervicodorsalTransition.jpg

5) GSP didn't understand my caution regarding compositing a vertebral  
series out of discrete illustrations, commenting "Since all the 3108  
cervicals are on the same figure at the same scale and appear to  
articulate with one another it is hard to see how there is a scaling  
issue."  Since this seems to be an earnest attempt to understand why  
his exercise with tracing paper resulted in a gopher-hunter, and the  
same illustrations turn out more biologically plausible in my ONP  
reconstructions, I re-reiterate that one cannot trust that just  
because the publication says the illustrations are all 1/10 scale, or  
whatever, that they in fact ARE all published to the correct scale.   
With Janensch, great care seemed to be given to the printing of  
illustrations of the original material (with the exception of the  
skeletal reconstruction :), but with the diplodocids in Hatcher and  
Gilmore, there are small discrepancies in scale (carefully measure  
total centrum length in the illustration, multiply that length by the  
purported scale value and compare what you get with the published  
textual values for that length).  The individual images are not all  
printed at precisely the same scale, which can lead astray those that  
just cut (or trace) and paste.   Trust but verify.

6) Finally, regarding GSP's remarkable proclamation:  "No modern  
mammal feeds higher than giraffes because what with dental batteries  
and big brains they are too big headed to be so long necked"

I can only respond:

"I have no response to that"

from the movie "Joe versus the Volcano".  Listen at:

http://www.moviewavs.com/cgi-bin/mp3s.cgi? 
Joe_Versus_The_Volcano=response.mp3

And more generally, about going on and on about sauropod necks, I  
wish to sign off by quoting (from the same movie):

"I'm not arguing that with you!  "I'm not arguing that with you! "I'm  
not arguing that with you!  Who told you that? ... if I said that I'd  
be wrong ... No!  I told you that!  Me!  What?  Maybe.  Maybe.   
Maybe.  Maybe!"

http://www.moviewavs.com/cgi-bin/mp3s.cgi? 
Joe_Versus_The_Volcano=arguing.mp3