Re: Death poses (Nuchal Ligaments)

["Matthew Bonnan" <mbonnan@hotmail.com>]

Mike Taylor wrote:
"Oh, are nuchal ligaments a done deal in dinosaurs now?  The last I
knew, they were just a vague hypothesis about how some sauropods might
have supported those long beam-like necks.  Has someone conveniently
found some soft tissue that I don't know about?"

So far as I know, all tetrapods (not sure about amphibians -- but definitely 
amniotes) have a nuchal ligament that runs with muscles such as trapezius, 
the spinalis series, and other neck related muscles/homologs. Also, so far 
as I know, no soft tissue data show a nuchal ligament, but it is being 
inferred because, again, all tetrapods (well, at least amniotes) have them.

"I've heard it suggested that the bifurcation in the neural spines of
diplodocids may have been for the purpose of forming a "trench" in
which a possible nuchal ligament could lie, but of of course that
doesn't work for taxa, such as the brachiosaurs, with non-bifurcated
spines.  Or does it?  I don't recall antelopes etc. having bifes, so
where do they keep their NLs?  Above the spines?"

Antelopes, humans, etc., have nuchal ligaments above/on their neural spines 
-- in ourselves, it is small and is integrated with trapezius, etc.  It (NL) 
is bigger in mammals with longer necks and heavy heads -- i.e., horses, 
antelope, etc.  Don't know if anyone's ever actually shown that the 
bifurcated neural spines actually correlate with a large nuchal ligament, 
although that has been suggested plenty of times for sauropods.

Matt Bonnan, Ph.D.

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