Theropod Scapula questions

[Toby White <mwhite@houston.rr.com>]

I've been trying to get my arms around the pectoral girdle, so to speak.  In 
the process of looking over a lot of shoulders (OK, I'll quit now) there seems 
to be a great deal of variability in how they are reconstructed.  This isn't 
surprising, since there is rarely any bone-to-bone articulation between the 
scapula and any portion of the axial skeleton (none in dinos, as far as I 
know).  However, this does raise a bunch of questions.

1) Quadrupeds are generally reconstructed with the scapulae tucked neatly up 
parallel with the vertebral column.  However, bipeds, particularly theropods, 
are usually reconstructed with the scapulae hanging down at a 45 degree angle. 
 Why?

2) How confident are we on the placement of the Theropod scapula along the 
vertebral axis? A few years ago, someone on this list quoted Ken Carpenter as 
saying "As all naturally articulated dinosaur skeletons show, the first dorsal 
rib bisects the scapula about midway along its length." Is this still the case? 

3) What is a "naturally articulated" pectoral girdle, given that there is no 
hard connection with the axial skeleton and the possible effects of taphonomic 
contraction on the soft tissue connections?

4) In a quadrupedal dino, where and how is the force of impact on the fore-limb 
distributed to the axial skeleton?  For Maniraptoran bipeds, the hand strike, 
flight stroke, or what have you, looks like it would create the opposite 
problem.  How is this strain distributed to the axial skeleton?  It looks as if 
the scapula would be the primary agent in both cases, but I don't see how it 
interacts with the ribs (or whatever) to do the job.

Thanks for any information you may have.

  --Toby White

Vertebrate Notes @
http://www.dinodata.net and
http://home.houston.rr.com/vnotes