[no subject]

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

On Jan 25, 2006, at 11:57 AM, Richard W. Travsky wrote ...

<< So, how big can a giraffe get? What's the biggest one on record?  
(since they're about it for something analogous) >>

That assumed analogy underscores that we really have two distinct  
topics of sauropod research:

1) the sauropods themselves, and all their wonder.
2) why many people presume that (at least some) sauropods went around  
looking like giraffes.

Let's do #2 for a moment:  Why DO people regard giraffes and  
sauropods as analogous?

Sauropods and giraffes are clearly similar (and clearly dissimilar):

1) they both have long necks
2) they are large herbivorous, quadrupedal terrestrial vertebrates
3) they both have opisthocoelous cervical vertebrae

but on the other hand:

4) the upturn at the base of the neck in Giraffe is reflected by the  
cervical osteology in ONP (Osteological Neutral Pose).
5) no corresponding osteological specialization is found in the  
sauropoda.  Instead the ONP suggests the base of the neck was a  
straight extension of the back.

The last point (#5) is a bone of contention. Some silhouette drawings  
suggest sauropod necks that naturally curve upwards, but under  
scrutiny, those silhouette drawings show subtle-but-cumulative  
geometric inaccuracies, and anyway, apparently at least some such  
illustrations are not even intended to depict the ONP.

So what hard (pun-intended) osteological evidence is to indicate  
giraffe-like curvature in sauropod necks?  In Scott Hartman's  
estimation, the WDC mount of Camarasaurus might reveal some ONP  
elevation in the cervicodorsal region, but dem bones, bless 'em, are  
still very much out of articulation and distorted.  There are,  
however, other Camarasaurus cervicodorsal vertebrae that can and do  
rearticulate well, such as CM 11069.  Those vertebrae, when placed in  
the close association they would have had in life, are straight in  
ONP.  Oh, and note that the matrix is not completely removed, showing  
the depth to which the condyle DID fit within the cotyle AND that the  
neck IS STRAIGHT in ONP with the zygapophyses in PRECISE neutral  
alignment.  See:

http://www.cs.uoregon.edu/~kent/DinoMorph/Camarasaurus/images/CM11069/ 
C10C11-lateralR.jpg

and others images under the camarasaurus pulldown at

http://www.cs.uoregon.edu/~kent/DinoMorph.html

So, getting back to research topic #2, why DO people like to believe  
in "Juraffes"? It is worthy of some study, I think.

It's also mostly a sauropod thing, not just a long-necked-Mesozoic- 
creature thing. For instance, Elasmosaurus (which puts most sauropods  
to shame for sheer number of presacrals) is usually envisioned as  
straight at the base of the neck:

http://www.bbc.co.uk/science/seamonsters/factfiles/closeup.shtml? 
elasmosaurus
http://www.geocities.com/sea_saur/elasmosaurus.jpg

... and only rarely is it depicted with a swan neck ... except <big  
ironic grin> as depicted by the Carnegie Collection toy:

http://www.dinosaursetc.com/catalog/000000150.1.jpg

So why put the bend in the sauropod neck if there's no hard evidence,  
and only a flawed analogy, to support it?

Allan Edels very appropriately brings Indricotherium into the  
discussion.  While introduced regarding head-heart distance, they  
represent a better analogy.  Massive body, high browser by dint of  
tall limb stature, interested in eating, defended by its sheer size,  
and not worried about having to outrun lions, that sort of thing.



[Incidentally, Mary recently assured me that, if the DML archive  
accidentally breaks a long URL by introducing spurious gaps, "Our  
audience knows to get the complete url" by multiple cutting-and- 
pasting.]