RE:about those claws

[MARK SHELLY <mshelly@msa.nwsearle.sea06.navy.mil>]

Jack wrote
> Birds have a special adaptation in their feet that allows them to perch.
> The tendons which control the toes run up the leg and are rather
> unelastic.  As long as the bird keeps its leg extended, the toes can move
> freely.  If the bird bends its leg, the toes flex because the distance
> between the origin of the tendon and the toes lengthens. This allows
> perching birds to sleep while perching.  Suppose the dromaeosaurids' large
> second claw worked in this manner.  When the animal ran and pulled one leg
> up, the second toe would flex and the claw would be pulled downward
> (someone mentioned that a dromie might disembowel itself if it kept its
> toe in the vertical position while running, made me think of this).
> When the leg straightened to contact the ground, the toe could be
> raised to the vertical position again to help prevent wear on the
> ground.  Also,if the dromaeosaurid attacked something, it might leap and
> extend its legs in the air (allowing the claw to assume the "retracted"
> position), then when it struck the animal, the impact would bend the leg
> and for the claw downward and into the prey.  With its initial momentum
> gone, the dromie would begin to slide down the side of the prey animal,
> dragging the claws (this would work better with the "all toes in the kick"
> theory). This assumes, of course, that the dromie was hanging on and/or
> attacking with its mouth and hands.

   If you reconstruct the foot based on birds - tendons running from the 
calf to the toes, then the toe claws will rotate down as they move the 
foot forward with the leg bent.  This is a great point.  It implies that 
the claw will stab into a tree or prey and allow lifting/supporting the 
dinosaur,s weight with this claw.  My opinion is that the hand claws did 
the most damage.  I would expect a little more shoulder muscle and 
"popeye forearms" than shown on most restorations.  Czerkas's models and 
Rachel Clark's drawing "thistle" are the best with this musclature.