Re: Swimming spinosaurus

[David Krentz <David.Krentz@disney.com>]

"Demetrios M. Vital" wrote:
>
> On 17 Jul 2001, Mickey Mortimer wrote:
> > It's a good question whether spinosaurid
> > hands could pronate, as no carpi are known, and the metacarpus is only
> > represented by a third metacarpal in Suchomimus.  Of course, they were
> most
> > parsimoniously similar to other basal tetanurines.
>
> Can *any* theropod hands pronate and supinate?  What is needed to allow
> this movement in the wrist?
>
> Thanks,
>
> Demetrios

  In order for pronation/supination to happen, the radius should have a
rounded end that acts like a kind of "roller" against the ulna.  Our own
arms are great examples of radio-ulnar rotation.  Very few, if any
dinosaurs, had that kind of adaptation.  For the most part, the proximal
end of the radius is flat and rectangular, and lays snug and flat
against the ulna, which would not allow that tucked and pronated look
that is present in early Greg Paul drawings of theropods.  To get the
palm to face downward, a theropod would have to lift it's arms up and to
the sides (like a flapping bird!)
  Sereno had a paper a few year back entitled "could theropods dribble a
basketball" that covered this topic.  His conclusion was that if a
theropod wanted to shoot a basket, then a granny-throw was the only
possiblitly.

David Krentz