Re: So-called Sickle Claws

["Peter Von Sholly" <vonrex@gte.net>]

NP- thank you for your thoughts and info.  What gets me is; I have this
turkey foot (I have seen a doctor but he said there was nothing he could do
for me- hahhaaa) but seriously, a foot from a wild upstate New York Turkey
and there are pads underneath it, of course.  On all the toes (which retain
their keratin sheaths) the skin and pad extend way down and onto the actual
claw itself.  That is, the claws protrude somewhat from within a skin/pad
covering.  Now since we are constantly evoking birds as the best living
anaologs for dinosaurs, I imagine the dromaeosaur foot was probably
similarly adorned- bringing both skin and pad going right down to the ends
of the toes and at least a bit further onto the claws themselves.  
I also have a cast of a velociraptor foot, and the "right angle"
articulation you mention betwen the phalanges II-1 and II-2 is only a right
angle when the toe claw is bent back as far as it can possibly go.
My main gripe is that I almost never see that toe in any but the most
retracted postion it could ever possibly assume, (as depicted by G. Paul in
Predatory Dinosaurs, for example, where it is bent bent so far that it
actually leans against the metatarsal!)  No matter what position the foot
is in!  Running, resting, walking... and this is the image that recurs in
virtually all restorations.  It looks absurdly wrong to me; I cannot
reconcile it with what I see in the bones.  If you have Don Glut's new
book, look at the photo of the mounted Deinonychus skeleton there.  The
second toes are almost laid flat with 3 and 4 and look much more natural
that way.  To me, you could even relax them a little more. Then look at the
same toes on the Dromaeosaur mount in the same book... bent straight up in
the air.  Doesn't that look a little weird?  Or is just me?  Anyway, thanks
for indulgin my questions and thoughts-
PVS

----------
> From: NJPharris@aol.com
> To: dinosaur@usc.edu
> Subject: Re: So-called Sickle Claws
> Date: Wednesday, August 27, 1997 11:46 AM
> 
> In a message dated 97-08-24 04:16:23 EDT, vonrex@gte.net (Peter Von
Sholly)
> writes:
> 
> > I disagree.  I believe there was a large "heel pad" under the distal
ends
> >  of the 3 metatarsals and that all three toes bent forward from there,
with
> >  pads of their own, especially under the claw of digit 2, the so-called
> >  killer claw.  There is plenty of room for that toe to reach the
ground.  
> 
> Maybe; but the only part of the toe that would be on the ground is
phalanx
> II-2.  That wouldn't provide a lot of support.  It looks to me like the
only
> part of the second toe that touched the ground was the "knuckle" between
> phalanges II-1 and II-2.
> 
> 
> >  And what about the animal's ability to walk, run and balance?  
> 
> And why is digit II so short and directed away from the direction of
> movement?  And why are phalanges II-1 and II-2 set up to articulate at up
to
> a 90-degree angle to each other?  And why are the muscle attachment sites
on
> the second toe so much more prominent than on the other toes?  And what
about
> that enormous, nearly semicircular claw?  Unless it was held up at least
to
> some extent, every step would have driven it into the ground!
> 
> (I have copies of Ostrom's drawings of the original foot in front of
me--_The
> Dinosauria_, p. 275)
> 
> 
> >  You don't
> >  think that would be compromised by the need to walk only on its two
outer
> >  toes?
> 
> It doesn't seem to be too much of a problem for ostriches!  And they put
most
> of their weight on only one toe!
> 
> The two outer toes of _Deinonychus_ were very nearly the same length and
ran
> parallel to each other.  Both were very long and robust.  The claws on
these
> two toes are rather flat, in sharp contrast to the claw on the second
toe,
> which is much more similar to the hand claws than to the other foot
claws.
>  The fourth metatarsal is splayed out from the third in order to increase
the
> area covered by the two outer toes.
> 
> These adaptations are unique to the Dromaeosauridae and appear designed
for
> shifting the animal's weight onto the two outer toes.
> 
> NP