Re: Bird flight once more (was Re: What is a Dinosaur? and semilunate carpal)

["Jaime A. Headden" <qilongia@yahoo.com>]

I wrote:

<<First, it would be good to clarify that dorsoventral movement of the wrist 
only occurs if the
arm is held outward, level to the horizon.>>

Chris Fisher (killerraptor20@hotmail.com) wrote:
 
<Imagine a traffic cop waving cars past - this is the movement of the hand I 
meant. same
orientation of the arm too. Could a maniraptor direct traffic? :)>

  probably not. The first maniraptoran with the ability to level the elbow to 
the height of the
shoulder was *Unenlagia*, thus only Avialae among Dinosauria can do this.

Chris also writes:

<I'm thinking all these changes made the arm and hand better for HOLDING prey 
but not very good
for FEEDING -  like using the hand to bring food to the  mouth>

  Hmm... Predation does not pertain to the feeding on the animal itself; unless 
the jaws are used
to kill the animal, as in cats or canines [dogs, wolves, etc.], jaws are not 
part of the equation.

and...

<But what about movement between the metacarpals and the carpal block - the 
distal surface of the
semilunate carpal. Could this act as a hinge? How was this contact strengthemed 
- or that between
individual phalanxes.>

  There is no joint between the distal carpals and the metacarpals in 
maniraptoriforms... This
contact is broad, and the semilunate is firmly appressed to the metacarpals. 
There is to a degree
one in *Allosaurus* and *Acrocanthosaurus*, but this contact is firmed by 
several pedicels that
prevent any joint from occuring. There is no way for a joint to be present 
between carpal and
metacarpal elements in any dinosar except for, possibly, *Blikanasaurus* and 
*Bugenasauria", which
have the proximal tarsals contact the proximal surface of the metatarsals. 
However, this is not
analogous...


=====
Jaime A. Headden

  Aaaaaaaaaaaaaaaaaaaahhhhhhhhhhhhhhhhhhr-gen-ti-na
  Where the Wind Comes Sweeping Down the Pampas!!!!

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