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functional morphology of killing claws and teeth



The idea that dromaeosaur claws were used for slashing has always bothered
me.  It always seemed to me that a better slashing design would be a fairly
straight, bladed claw like that of the cassowary (which certainly does use
it for slashing).  

Slashing instruments make poor gripping instruments, and vice versa.  I
have read Tom Holtz's previous post on killing strategies, which suggests
that cats use a combination of slashing and biting to kill their prey.  I
was under the impression that they usually kill by biting, although I have
no doubt that big cats can put enough power behind their claws to slash
fairly well.  But there are also situations in which the claws are needed
for gripping, and their design presumably reflects a compromise between
slashing and gripping.  A great deal of power is needed to engage the
slashing function.

Tooth design also reflects function.  The typical snake tooth, which is
used for gripping, is somewhat recurved and has a ridge on its mesial
margin to aid penetration.  Its distal margin is rounded to prevent
slipping.  This can be contrasted with the tooth of a slasher, like the
Komodo dragon, which is also somewhat recurved, but has serrated carinae on
both mesial and distal margins.  

I can easily imagine a dromaeosaur leaping onto a larger dinosaur,
imbedding its sickle claws deeply and using its front and hind limbs in
opposition to grip the animal tightly while it repeatedly takes chunks out
of its back with its teeth.  I have a somewhat harder time envisioning it
exerting enough power (front limb power is as important as hind) to slash
fatal wounds.  But I would like to be persuaded otherwise.  And please
don't tell me it's a combination of biting and slashing.  I hate those
complex truths!  

Just kidding.   

Best regards,

Dave