Re: Sauropod necks (Re: DinoMorph Strikes Back!... or does it?)

[David Marjanovic <david.marjanovic@gmx.at>]

Whew! Wow! What a treatise! 42 kB in plain text! Impressive. Very 
interesting!

> Here's where things get really interesting. Kent claims that the fused 
> cervo-dorsals of AMNH 5761 (cervicals 11 & 12, the last two in the neck)
> are critical to the issue, and that they are fused straight [...] I
> agree that these bones are critical and also suggest you check out
> Kent's photos (and/or the technical drawing in Osborn and Mook 1921
> AMNH Mem 3, which is identical).

Due to a rather incredible stroke of luck, Osborn & Mook 1921 is lying 
right next to me. Plate LXVIII illustrates the fused pair, identified as 
cervicals 12 and 13 of "Amer. Mus. Cope Coll. 5761-_a_". (Plain 5761 is 
the preceding plate.)

> Kent says they lie flat on the table. No they donâ??t, the posterior
> rim of 12 is clearly off the surface.

True.

> Put the cervicals on a hard surface and they would rock.

True.

> Also, the antero-ventral rib articulations of 11 project strongly
> ventrally and act as props. Knock off all the parapophyses [...] and
> those cervicals would really rock, baby.

True.

> But things get better still. Look at the zygapophyses. Tightly
> co-ossified, it appears that they are close to or at full, neutral
> articulation.

Looks like it.

I can only find one possible objection: The vertebrae are distorted. The 
illustration of the pair in cranial view shows that the neural arches are 
tilted to the left. If this distortion was due to what geologists call 
"transpression", it is imaginable that the centrum of vertebra 11 could 
have been distorted upwards. It doesn't look like that to me -- but then I 
don't have any experience with recognizing distortion in fossils.

What do you think? Is it imaginable that the fused pair was straight in 
life and only bent by diagenesis?

> Itâ??s yet another head scratcher that in a dinomorph figure Kent shows
> Apatosaurus and Diplodocus with their heads at what he restores at their
> maximum vertical reach, which is not very high, but shows Brachiosaurus
> at only its NOA, which is not much higher. Thatâ??s comparing apples and
> oranges. Why not show the brachiosaurâ??s neck in a more elevated
> position, say 45 degrees which would seem to be no problem even assuming
> Kentâ??s very conservative rotation arcs?

The website explains why: _because_ the neural arches and thus the 
zygapophyses aren't preserved, it isn't possible to identify the limits of 
dorsal and ventral flexion, it says.

One last thing: There's a good reason why it's "cervicodorsal" rather than 
"cervo-dorsal". In Latin _cervix_ (think _cervic-_ with the ending _-s_) 
means "back of the neck", while _cervus_ means "deer". :-)

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