RE: FLIGHT & CATS

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

Tracy Ford (dino.hunter@home.com) wrote:

<Where is the glenoid in gliding squirrels and lemurs? Is it high on the body 
like birds?  I was
thinking of going to the San Diego Zoo and trying to get some of the handlers 
to show me. Maybe
soon.>

Tim Williams (tijawi@hotmail.com) wrote:

<Good question.  Though you would probably want to compare gliding and 
non-gliding squirrels. 
Even those animals that don't glide may have a glenoid facing upwards for 
normal arboreal living
(vertical clinging, reaching up to grasp branches, etc).  Definitely something 
worth looking
into.>

  I can answer this, if you want a quick answer. Based on my observations of 
the pectoral girdles
of various arboreal animals, including lemuriforms and relatively arboreal 
primates, the glenoid
faces laterally and to the posterior. Without relocation of muscle attachment 
on the scapula,
reshaping the scapula, and rotation of the scapula, the glenoid cannot face 
dorsally -- this would
result in a shallow scapular crest, a robust coracoid process, a very broad 
scapula, oriented
oblique to the vertebral column, and the humerus attached so that the forearms 
bent outwards only;
it would not be further possible, based on a cursory [thanks, Darren :)] 
examination, for the arm
to rotate at the shoulder as much as it does in the normal position. One loses 
mobility at such a
position; humans enjoy the mobility we have because the glenoid facets 
laterally _only_, and the
humeral head is globular, allowing the greatest range of movement.

  In gliding squirrels, it appears to face normally, i.e., ventrally, rather 
than in any other
direction, as in "normal" squirrels, but don't quote me on that.


=====
Jaime A. Headden

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

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