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Theropod forelimb design and it's implications...
When asked why skeletal restorations accompanying his papers always showed
theropod hands and forearms in a neutral ("shaking hands") position (as
opposed to G.S. Paul's restorations where they are always shown pronated),
Paul Sereno once indicated (personal communication) that theropods could
not pronate/supinate their hands because of the anatomy of their wrist,
that pronating hands were a feature of primates and not dinosaurs.
Is this a commonly agreed upon theory? (Is there such a thing as a
commonly agreed upon theory?)
My inexperienced eye cannot find any feature of theropod anatomy which
prohibits pronation/supination. Dr. Sereno may have been referring to the
lunate metacarpal, but I don't see how this would restrict flexibility in
what is basically a forearm rotation.
I have trouble with this theory for three reasons:
1) Ancestral reptiles could rotate their forearms as part of quadropedal
2) I am under the impression that earlier quadropedal archosaurs held
their forelimb pronate while walking. For that matter, all quadropedal
3) What is the utility of a grasping manus which would be most useful
(correct?) if moved in the sagittal plane, but can only grasp in a
Does anyone have any insight?
Jonathan R. Wagner