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Re: Palms in




Patrick Norton wrote:

>
> I'm still not clear about the relationship between the radius/ulnar and the
> semilunate carpals with respect to the "palms in" attitude of the hands and
> the "sidways" motion Luis refers to above, although that's my general
> question.

The mechanics are quite simply understood when you 'play' with a cast of the
Deinoychus hand. The hand sideways rotation thanks to the pivotal action of
the semilunate carpal is evident. I did it with Alan Gishlick 'in situ' at the
latest SVP meeting (bringing a Deinonychus hand in the pocket is always handy
although I can't think of many people that would do it except Alan and Robert
Bakker). I have also seen  diagramatical sketches on Alan's paper. Full
reference of the paper and a small quote is included in my "Deinonychus, a new
look for the year 2000" in my website. You might like to contact him in
person.
Another interesting point is that Alan argues for the 'grasping. almost
opposable freedom' of the third finger, while 1 and 2 are almost interlocked
together.  The range of mobility of fingers one an two is quite limited and
could bend rather weirdly slightly backwards!. The second finger was possibly
the bearer of feathers (specially in Archaeopteryx). Alan Gishlick considers
Archaeopteryx ' hand virtually the same as Deinonychus. The rest of
maniraptoran hands are just more or less variations of a similar system (that
makes for Scipionyx, Ornitholestes, and so forth) perhaps in more primitive
ways.  Allosaurus do not have a semilunate as such, but Dan Chure showed an
articulated fossilized hand that bent curiously sideways... so Allosaurus
might have been a very primitive maniraptoran.
I may be wrong

>
> Did you catch the brief scene in WWD in which the juvenile Utahraptor stood
> atop a prey animal and squawked(?) at the adults who were hogging the food?
> In a very natural looking and convincing fashion, it alternatively folded
> its arms and hands against its body in birdlike fashion then extended its
> arms and slashed with its claws with a "prey capture" type of motion
> described by others on this list  It was the most natural looking video
> depiction of this possible function that I've seen so far...
>
> PTN

Yes. The interesting thing is that there is complete confusion in Jurassic
Park. Sometimes you have it one way, sometimes you have it another...
acccording to Spielberg's needs I suppose... those things could do anything.
In the  T.rex attack of the original JP, there's also a moment that  the hands
act in a 'natural way' and in side motion. But most of the time they are
chimeras busily trying to open doors.


--
Luis Rey

Visit my website on http://www.ndirect.co.uk/~luisrey