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Re: Brachiosaur Neck Posture Change Question



Title: Re: Brachiosaur Neck Posture Change Question
Kris,

Sauropod necks were probably braced against mechanical loading in the same way that crocodilian necks are.  Have a look the following paper for details of the anatomy and biomechanics of the cervical bracing system in both extant and fossil crocs.  

Salisbury, S. W. & Frey, E.  2001.  A biomechanical transformation model for the evolution of semi-spheroidal articulations between adjoining vertebral bodies in crocodilians.  85-134.  In Grigg, G. C., Seebacher, F. & Franklin, C. E. (eds).  Crocodilian biology and evolution.   Surrey Beatty & Sons, Chipping Norton.

You may also want to check out . . .

Frey, E. & Martin, J.  1997.  Long necks of sauropods.  406-409.  In Currie, P. J. & Padian, K. (eds).  Encyclopedia of dinosaurs.   Academic Press, San Diego, London, Boston, New York, Sydney, Tokyo and Toronto.

Martin, J., Martin-Rolland, V. & Frey, E.  1998.  Not cranes or masts, but beams: the biomechanics of sauropod necks.  Oryctos, 1 113-120.

Cheers,

Steve


---------------------------
Dr Steven Salisbury
Palaeontology and Geology, Queensland Museum
PO Box 3300, South Brisbane, Q 4101, Australia

email: steve_salisbury@bigpond.com     
phone: +61 (0)7 3842 9433 (office) +61 0407788660 (mobile)

http://www.Qmuseum.qld.gov.au/organisation/sections/PalaeontologyGeology/




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From: MariusRomanus@aol.com
To: dinosaur@usc.edu
Subject: Brachiosaur Neck Posture Change Question
Date: Wed, 20 Mar 2002 9:58 AM


This was buried in one of my lasts posts.... I don't think anyone saw it... If you did.... I'm just being a pest. :-)

And while I'm still in a Brachio sort of mood...... I was thinking about the restoration change from the mildly sloping swan-like neck to the "lets stick it straight out at an angle like a warped 2x4".... Is this just playing on the percentage of ossification of the elongated cervical ribs dictating how flexible the neck actually was.... or... is there something else going on here that I don't know about? I know that with a back angled up between 25-35 degrees, in order to get the neck to look like a more vertical S, it would require some hefty flexibility at the base of the neck, not to mention the bottom third of the necks vertebral column would really have to be straining. If memory serves, Kent Stevens figured out a slope in the neck between 10 and 15 degrees per vertebra? And I was looking at the cervical vertebrae........ The first 6 have low, rounded neural spines... but when you get to 7 there is this huge triangular-looking spine that looks nothing like the others! ! before it. This I'm guessing is where the big dorsal neck elevating muscles were anchored... longer lever arms....simple mechanics....

With this tall neural spine, and the longer vertebrae at the base of the neck, is this more of the real reason why recent reconstructions have the neck in a straighter orientation, with a slight slope and with a thicker dorsal side made up of bulging muscle close to its base? Did the neck form more of a gentle curving over after the 7th cervical? If the condition of the cervical ribs were a mildly ossified state, would this gentle curving over be a big problem for the animal?

Kris