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Re: dino-lice



2011/4/20 Jason Brougham <jaseb@amnh.org>:
>
> Last, in Shuvuuia and Mononykus, don't the myriad tiny teeth that lack
> individual sockets, and which are set together in an alveolar groove, look
> different from what we'd expect in a scavenger?
>
Agreed. They do not seem good for the task.

I was thinking perhaps we should evaluate hypotheses taking into
account claw shape. For example, anteaters as far as I know, have
straight ungual phalanges (although the claw is ussually curve). They
also present a near triangular section, unlike the more recurved and
round-sectioned claws of Mononykus. Fossorial habits can be more
likely dismissed, because these animals have wide hands, without digit
reduction, and the claws are dorsoventrally flatter, as in moles (in
addition, it is unlikely such an animal with long appendages and short
forelimbs to have been living like a mole). Bears and badgers seem to
have more laterally compressed claws, perhaps to increase their
resistance because of their lenght. The not so great curvature agrees
with the lack of hooking function, as indicated by Brad. The conical
shape with slight curvature seems good for piercing, as in some
raptorial birds. Perhaps the adults used this as agression devices, as
do certain cervids with canines, or birds with spurs...

Other possibility: may the well developed muscular processes just
imply that the skeleton has reduced in lenght in a greater degree than
in other dimensions (transversal), or that the musculature in
alvarezsaurs did not reduce as fast as the skeleton in the forelimb?
It may not be just a way to reduce a limb, I guess (although do not
know other cases). Or may it be that the only reduction was in
forelimb lenght, with the musculature and processes keeping the same
power as in the original limb, just that now they look more prominent
because of the reduction in lenght.