Re: Dynamic modeling deinonychosaur claws

[don ohmes <d_ohmes@yahoo.com>]

Personal observations gleaned from several rural dogs:
1) the weak point is usually not the claw sheath
itself, but the join between the sheath and toe-- when
stressed the entire sheath is pulled off, leaving just
the core. Don't know if this applies to dinoosaurs...

Don

--- Phil Bigelow <bigelowp@juno.com> wrote:

> All well and good.  But note that my question was
> about the relative
> *strength* of a curved blade compared to a straight
> blade with the same
> cutting surface length.  In particular, the relative
> susceptibilities of
> each to torsional stresses and the relative shear
> strengths of each.
> 
> On straight blades, the tip is far from the "pivot
> point" (aka, the
> articular surface).  On a strongly curved blade with
> the same cutting
> surface length, the tip is closer to the pivot
> point.  This gives the
> curved blade less leverage, but possibly greater
> strength.  For both
> dinosaur predators and knife users, this may be a
> worthwhile tradeoff.
> 
> It may be useful to computer model and then test the
> relative shear
> strengths and torsional strengths of the curved
> pedal unguals of various
> curved-claw predatory dinosaurs.  It would be
> valuable to know the
> absolute maximum amount of force that each species'
> unguals can take
> before they break.  Test for maximum sagital force,
> maximum lateral
> force, and maximum twisting force.  Even knowing the
> maximum compressive
> force may prove informative.
> 
> <pb>
> --
> 
> 
> On Wed, 02 Nov 2005 15:31:56 -0500 Michael Habib
> <mhabib5@jhmi.edu>
> writes:
> > Well, two comments on curvature and cutting
> surface:
> > 
> > 1) The cutting surface would only be increased in
> length if the claw 
> > 
> > were curved in the other direction (recurved).
> > 
> > 2) The concept of a curved edge (be it a claw,
> tooth, sword, etc) 
> > adding appreciably to total cutting power by
> adding edge length is 
> > something of an urban legend.  The total amount of
> 'added edge' is 
> > pretty minor.  Curved edges have advantages, but
> cutting is not one 
> > of 
> > them.  A straight edge cuts just as well.  (I,
> personally, was quite 
> > 
> > surprised to learn this little tidbit).
> > 
> > Cheers,
> > --Mike
> > 
> > On Wednesday, November 2, 2005, at 02:04 PM, Phil
> Bigelow wrote:
> > 
> > > No one has mentioned the relative shear
> strengths of long 
> > straight
> > > unguals vs long curved unguals.  With a curved
> claw, the cutting 
> > > surface
> > > length can be quite long, yet the entire claw is
> shorter overall.
> > >
> > > All other things being equal, could curved
> cutting surfaces be 
> > less 
> > > prone
> > > to breakage than straight cutting surfaces with
> the same blade 
> > length?
> > >
> > > <pb>
> > 
> > 
> 
> 
> --
> 
>