Re: I knew it!

[GSP1954@aol.com]

In a message dated 7/18/3 4:36:33 PM Tim wrote:

<<Another likely exception is the higher Maniraptora.  The manual digits of 
oviraptorosaurs and deinonychosaurs have a tendency to show reduced 
mobility, on account of (1) the locked interphalangeal joints and/or (2) the 
close appression of the proximal metacarpals.  (The oviraptorid _Heyuannia_ 
even shows some carpometacarpal fusion).

Thus, maniraptoran hands would have been capable of limited manipulation 
anyway.  The biomechanical studies of Gishlick indicate that deinonychosaurs 
could only grasp objects using both hands, and this may have been true for 
oviraptorosaurs as well.  There may have been an adaptive advantage to this 
inflexible manus (such as for grasping large prey, in the case of some 
deinonychosaurs), or it might be a relict of an ancestry among flying 
theropods.
>>

In terms of reduced mobility I was refering to radius-ulna rotation of the 
lower arm and hand, not the metacarpals and gingers. As for the latter Tim's 
later suggestion is probably close to the mark. The Jehol dromaeosaurs all had 
flattened central fingers with severely limited flexion in order to support the 
outer primaries. 

G Paul