[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]

Re: I knew it!

Greg Paul wrote:

I've always been skeptical about this because it makes no functional sense for animals that used their hands for manipulation to have such limited lower arm and hand rotation. [snip]
Am very suspicious of arguments that this was true of any dinosaur, except perhaps those with such reduced arms that it does not matter.

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.


The new MSN 8: advanced junk mail protection and 2 months FREE* http://join.msn.com/?page=features/junkmail