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On 4/23/2011 2:13 PM, Jason Brougham wrote:
I like the idea that the single-clawed forelimbs of alvarezsaurs were
> used to penetrate carcasses (especially from the inside), or that they
> were used to prise parasites off hides - either from the hides of
> other species, or from each other (as a grooming tool). Thus
> returning us to the origin of this thread: Dino-lice.
Those functions do not explain the limb shortening trend in the group.
Both jobs could be accomplished better with unmodified, primitive, arms.
Exploitation of the carcass interiors, hives, nests, hollow logs, stumps
and random holes that serve as refuge and habit for various grubs,
larva, insects and small animals would explain forelimb truncation,
however -- once it assumed that prey is captured w/ the jaws rather than
the hands in the ancestral state, as seems likely or even obligatory
from the haplocheirids forward.
Perhaps it might seem overly broad to use the term "locomotion" in
regard to very short limbs which are used to assist the snout in
entering and retreating from nooks and crannies that are just large
enough the head (or even slightly too small in the case of an
'expandable' substrate), but it is nonetheless technically correct.