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Re: A problem of cartilage



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