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Re: semilunate carpal



Graydon wrote:

Some maniraptorans are obviously evolved to attack prey as large or
larger than themselves; in these cases, seizing isn't going to be a good
description of the interaction with the prey animal.

"Grappling" is probably a better word.


The other thing is that the greatest relative strength would have had to
evolve in small forms, since those are the ones that became volant, and
minimal levels of useful for flight arm strength would already have to
be enough to move *them*; locomotor strength levels, but in a limb that
couldn't be used for walking.

Yes, but just look at the size of the sternal plates in these small maniraptorans. They anchored some pretty heavy-duty muscles.


Imagine how much strength would be needed by a _Deinonychus_ to cling on to a bucking, heaving _Tenontosaurus_ fighting for its life (literally). Or a _Velociraptor_ trying to hold a _Protoceratops_ so it can kick it with its slashing foot-claw - while trying to avoid being mauled by the _Protoceratops_'s beak.


Is there a known biomechanical reason why the use of the 'predatory
stroke' might not have been to align the maniraptoran, relative to the
prey, rather than to move a small prey animal toward the jaws?

The predatory stroke might have co-opted in arboreal theropods to negotiate predatory descents, from trees to the ground. But that's another story.


That's
reasonably consistent with tree climbing, and a steady increase in
stength to the point where the arms were capable of becoming locomotor
organs.

I think predatory adaptations in the forelimb and manus pre-adapted small theropods to tree-climbing. Darren Naish wrote a nice paper on this recently.



Tim



---------------------------------------------------------------------

Timothy J. Williams

USDA-ARS Researcher
Agronomy Hall
Iowa State University
Ames IA 50014

Phone: 515 294 9233
Fax:   515 294 3163



From: Graydon <graydon@dsl.ca>
Reply-To: graydon@dsl.ca
To: Tim Williams <twilliams_alpha@hotmail.com>
CC: dinosaur@usc.edu
Subject: Re: semilunate carpal
Date: Tue, 7 Aug 2001 18:17:21 -0400
--
                           graydon@dsl.ca
               To maintain the end is to uphold the means.


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