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Re: Rigid dinosaurs?



Out of sheer love of argument, I considered taking the "rex is a 
mega-terra-vulture" side of this debate. Unfortunately, however, I got nothing. 
Absolutely zip.

On the other hand, finding that one of the largest bipeds that ever lived in 
Earth gravity had a well-developed sense of balance is less than surprising, 
and supports the idea that once down, the prospects of getting up were 
uncertain. Kudos to Dr. martin for finding the evidence. I don't see how it 
bears on diet, though. Just getting water would have been tricky w/out 
Wallenda-like balance.

Don


----- Original Message ----
From: Allan Edels <edels@msn.com>
To: dinosaur@usc.edu
Sent: Friday, February 17, 2006 12:06:36 PM
Subject: Re: Rigid dinosaurs?

Kent, et al:

It seems that Jack is equating stiff ligaments with ossified tendons.

>>"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."

On what extant animal is he basing his analysis that "the amount found in 
the vertebrae is proportional to how stiff the ligament would have been,"?  
Does anyone know, or have a guess?

He seems to be ignoring physics in his conclusions.

Kent's example of automotive springs is quite apt and more to the point.  An 
additional note, the larger the vehicle, the larger and stiffer the 
springs/shocks - therefore, the larger the animal, the larger and the 
stiffer the [nuchal] ligament.

Allan Edels

>From: "Kent A. Stevens" <kent@cs.uoregon.edu>
>Reply-To: kent@cs.uoregon.edu
>To: dinoboygraphics@aol.com
>CC: DML <dinosaur@usc.edu>
>Subject: Re: Rigid dinosaurs?
>Date: Fri, 17 Feb 2006 08:29:37 -0800
>
>Scott Hartman's "stiff as an ostrich neck" analogy is apt.
>
>Furthermore, to equate ligaments with rigidity only disregards their  roles 
>as passive tensile structural elements and in energy storage/ recovery 
>and/or damping.
>
>Race cars and dump trucks (choose your analogy) have stiff springs  and 
>shocks for reasons relating to dynamics, not just the static  support of 
>the (vehicular) body.  Importantly, they aren't rigid,  they are stiff.
>
>It would not do for tyrannosaurids to be flopping all over the place  as 
>they ran briskly from one carcass to the next in a frenzy of  competitive 
>scavenging.
>
>Kent