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Gregory S. Paul <GSP1954@aol.com> wrote:
> The extreme musculature indicated by the ossified keeled sternum and big
> olecranon process combined with an enormous claw leave little doubt that
> alvarezsaur arms where for tearing something apart. The shortness of the arms
> increased their power via leverage. I like to think it was termite mounds,
> which I believe have been discovered from that time. Display feather
> does not explain any of the features.
There is no doubt in my mind that the forelimbs of alvarezsaurs were
used to apply powerful forces. However, as raised on this thread (and
elsewhere), the forelimbs are so short that attacking a termite mound
required the alvarezsaur to have its chest pressed against the mound.
Not only can't the alvarezsaur see what it's doing, but its body is
directly exposed to a seething mass of aggravated termites.
Also, among extant anteaters (vermilinguans), attacking a termite
mound isn't as simple as just standing over it and letting rip. For
tamanduas, which attack termite nests and termite-infested wood, the
forelimbs are capable of a range of forelimb motions - side-to-side
and fore- and -aft - in order to pull apart the nest or wood in the
direction of least resistance. Grasping abilities of the manus and
scooping motions of the forearm also help in breaching and tearing the
nest or wood. All these abilities were lost by alvarezsaurs,
alongside truncation of the forelimbs. So from this standpoint, the
anteater analogy is not particularly robust.