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