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Re: Theropod limbs - how mobile?



 
 
 
My question is not whether Dienonychus could kill a cat!
 
*** My response is simply a derivative of your example in comparing human hands to the dromaeosaur manus.
 
What I'm asking is why the immobile hands would be better at killing the cat than a Dienonychus with more mobile hands.
 
Basically, if the SLC and immobile fingers are to be explained as predatory adaptations and not wings, what makes then better for predation?
 
*** The more solidly built / less articulations built into the grasping organ, the more efficiently it is able to complete its function. The more play/joints
there are in the mechanism, the less effective the applied force will be and the more possibility there is for damaging the device at it's weak points.
Immobility of unnecessary joints ( phalanges in digit 3), means the segments of the digits are reduced to their lowest common denominator at which
point they will act with maximum efficiency as grasping tools.  Locking up metacarpals 1-2 with the SLC reduces that complex into one simplified
structure, better at handling external stresses than if they acted as individual elements. All of the above in association strong pectoral adduction,
robust collateral ligaments and flexion of digits / unguals at necessary key points only, translate into maximized adducting / grasping force. 
 
***Although extra movable joints provide increased dexterity in manipulating objects, the overall strength in the digit is then compromised accordingly.
 
Mike Skrepnick