ARGH!! SAUROPOD NECKS

[darren.naish@port.ac.uk]

Hi Matt, many thanks for your response. BTW, didn't know that you 
were in phd land. Belated congrats!!

You wrote...

> I don't think Stevens or Parrish say that the necks are inflexible. 

Well, ok: but I said 'relatively' inflexible. While they don't state it, I 
think they posit less flexibility in diplodocoid necks than people had 
imagined before, though seeing as no one had explicitly depicted what 
sort of flexibility they imagined, this is arguable. OTOH, there are 
Uncle Bob drawings of _Diplodocus_ sweeping its neck far far to the 
side (frontispiece or similar in _Dinosaur Heresies_).

> Criticisms about the neck position seem to stem from the idea that in
> mammals the discs between the vertebrae can be thick and can add to
> the flexibility of the neck.  [snip]
> So far as I know, disarticulation of zygapophyses does
> not occur even in camels and okapis.

I think this idea stems from comments Jeff Wilson made during an 
SVP presentation. He showed a dromedary looping its neck over on 
itself and said that it was pretty much impossible to get a naked 
skeleton to do it. However, IIRC the direct criticisms that have been 
leveled at the Stevens-Parrish study don't concern comparison with the 
different verts of mammals, but with the accuracy of the data they used 
in their reconstructions (Upchurch in _Science_). I also recall Paul 
Upchurch mentioning that flexibility in the cranial dorsals would also 
have an effect on neck flexibility, though I cannot remember if he 
stated this in his _Science_ response.

> "-- Those who work on tooth microwear seem pretty confident that
> diplodocoids were not feeding at ground level."
> 
> This comment stems from the idea that only conifers and other woody
> plants could cause dental microwear.  However, horsetails, which
> contain silica, were abundant during the Jurassic..... [snip]

The comment about microwear is a reference to diplodocoid enamel 
lacking the pits caused by grit ingested when feeding near the ground, 
not an implication that the teeth lack tooth-food microwear (whether 
caused by conifers, horsetails or whatever). At least that's my 
interpretation after reading Fiorillo and Barrett and Upchurch, and 
talking about it with Barrett. What effect food choice has on 
microwear is a complex area though (cf. Solounias and Janis!) and I 
suppose it's probably not that simple, unfortunately:)

Gotta go catch a ferry. Later.

DARREN NAISH 
PALAEOBIOLOGY RESEARCH GROUP
School of Earth & Environmental Sciences
UNIVERSITY OF PORTSMOUTH
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