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Re: tiny-armed theropods

On 10/12/2011 1:28 AM, Tim Williams wrote:
I've wondered about this.  It is likely that bipedality preceded
predatory behavior in dinosaur evolution.

This is a new idea to me. How come?

The study of Martinez et
al. (2011) further indicates that the ancestral body plan for
dinosaurs included a proportionately long forelimb (~45% hindlimb
length) and a sharp-clawed manus capable of hyperextension.  Theropods
show a shift to a more raptorial/grasping manus (elongate penultimate
phalanges of manus, etc).  Nevertheless, it appears to me that once
dinosaurs became bipedal it was a case of: "So, what do we do now with
these appendages?"

A consequence of the balance-beam type body -- erect bipeds are not constrained relative to arm length, but have no use for tails.