Re: Sauropod spines

["Scott Hartman" <scott_hartman@hotmail.com>]

Dan,

1) how far might this trait extend into sauropoda? - Your guess is as good 
as mine.  Diplodicus is the only sauropod currently known with these spines, 
and it is notoriously hard to plot a curve from a singe point.  I would say 
this, it is unlikely that the spacing, height, and placement of the spines 
would be consistent amoungst the sauropoda, even if their presence is 
widespread.

2) are these spines elongated scales, as in the iguana's spines or bony 
scutes, as in the spines of stegosaurs?. - Definantly not bony plates ala 
stegosaurs.  I don't know of any topological impressions found on the 
spines, so whether they were elongate keratinous structures (like scales) or 
some other soft tissue (like cartilage) covered with skin seems undecided.  
Perhaps someone online has seen the firsthand?

3) are these spines associated with the vertebrae under them?  That is, does 
every vert have a specific number of spines? - Apparently not as far as they 
are known.  Over the tail, there seems to be more spikes than vertebrae.  
Again, if you want to assume a broader distribution of these characters 
amoungst Sauropoda, then I would suspect that this varies a bit.  Hopefully 
future finds will shed some light.

One last thing, everybody has been puting these only on the dorsal midline 
of Diplodicus.  Certainly on the whiplash this seems to be the case, but 
it's been mentioned to me that the number of elements found that weren't in 
direct association with the body are great enough that these spikes may have 
extended to other parts of the body.

Scott
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