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Re: Rigid dinosaurs?

I wasn't there for Horner's presentation on his "microscopic analysis of the dinosaur's vertebrae", but I assume he was referring to the interspinalis ligament? Having dissected a few ratites, I was already convinced by the gross morphological similarity, not to mention that it's a level one EPB inference AND you can track the character's homology through the fossil record to early birds.

I'm sure the interspinalis ligaments made T. rex necks just as "stiff" as it does modern theropods, like ostriches. Of course tyrannosaurs have fewer cervicals than extant birds, and they are less elongate, but really, this is stupid; the ligament was likely elastic, as it is in extant theropods, and was there to reduce the load the dorsal axial musculature had to support when the head and neck were in a fairl neutral pose. It wouldn't have constrained T. rex neck mobility any more than the osteological articular range of movement allows. If he was interested in a range of movemment study, Jack should have asked Kent Stevens to help him out...of course Kent might not have comeup with the answer Jack wanted.

And now I can look forward to 5 more years of kids asking "Is it true that T. rex was just a scavenger?"

Scott Hartman
Science Director
Wyoming Dinosaur Center
110 Carter Ranch Rd.
Thermopolis, WY 82443
(800) 455-3466 ext. 230
Cell: (307) 921-8333


-----Original Message-----
From: W. F. Zimmerman, wfzimmerman.com <wfz@wfzimmerman.com>
To: dinosaur@usc.edu
Sent: Fri, 17 Feb 2006 09:37:02 -0500
Subject: Rigid dinosaurs?

Dr Horner and colleagues carried out microscopic analysis of the dinosaur's
vertebrae. They found tissue remnants related to the animal's nuchal
ligament, which provides passive support for the head and neck.

Since the amount found in the vertebrae is proportional to how stiff the
ligament would have been, the researchers determined it would have been very
rigid in their T. rex.

"We think this applied to all dinosaurs, certainly all saurischians - all
the meat-eating dinosaurs and all the sauropods," Dr Horner said.

"I think we need to re-model dinosaurs and think of them as being very
rigid. They're just not as fluid as we thought."
They would have needed lots of space to turn in order to avoid falling over,
he added.

--They sound like my son's plastic dino figurines.
--This sounds like a lot of extrapolation based on a small number of data
--My gut reaction is that rigidity isn't very adaptive. It's hard to
imagine millions of predators tottering around in straight lines for tens of
millions of years...

-----Original Message-----
From: owner-dinosaur@usc.edu [mailto:owner-dinosaur@usc.edu] On Behalf Of
Sent: Friday, February 17, 2006 8:22 AM
To: dinosaur@usc.edu
Subject: Thanks

Thanks very much to all that send me the papers.


Pablo Chiarelli
Curador y Técnico Preparador
Fundación de Historia Natural Félix de Azara.
Departamento de Ciencias Naturales y Antropología.
CEBBAD - Universidad Maimónides.
Valentín Virasoro 732 (C1405BDB) Ciudad Autónoma de Buenos Aires, República
Argentina. Teléfono/fax: 4905-1100 (int. 1228).
Página web: www.fundacionazara.org.ar


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