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Re: Alvarezsaur spurs (was Re: dino-lice)



On Fri, Apr 29, 2011 at 6:26 PM, Augusto Haro <augustoharo@gmail.com> wrote:

> Given that science seems to mostly advance by rejecting hypotheses
> (according to Popper and his followers at least), perhaps better than
> saying what alvarezsaurids did is to say what, given evidence, was
> physically possible for they to do (not trying to lecture anyone! -
> except perhaps myself). Then we would act by discarding possibilities,
> and we can find a set of possible behaviours which may well have been
> accomplished by the animal (even if not all were actually accomplished
> because of behavioural or phylogenetic constraints). It seems we can
> discard at least alvarezsaurids did not fly, brachiated like
> hylobatids or crawled like snakes. :-)  We may then prefer, given
> physical possibility, the more parsimonious inference given the
> behavioural repertoire of extant bracketing forms.



For _Mononykus_, this was the precise purpose of Senter's 2005 study:


Senter, P. (2005) Function in the stunted forelimbs of _Mononykus
olecranus_ (Theropoda), a dinosaurian anteater.  Paleobiology 31:
373–381.


However, despite the strong biomechanical support for the execution of
scratch-digging or hook-and-pull movements by the forelimbs, some of
us (in a somewhat hand-waving fashion) are reluctant to embrace the
idea that alvarezsaurs were specialized for myrmecophagous habits.
I'm not dismissing the proposition that _Mononykus_ (and other
alvarezsaurs) used their stunted forelimbs to tear open insect-nests
or infested wood; but I have reservations about this being the *only*
task the forelimbs were used for, or that ants and termites were the
*only* thing _Mononykus_ ate.  Hence the intuitive attraction of
alternative (but not mutually exclusive) lifestyles - like feeding on
carrion, or eggs.


The alvarezsaurs might have been most similar to the extant aardwolf
(_Proteles cristatus_), which feeds predominantly on termites, but
also feeds on eggs and small prey (other insects and larvae, small
mammals).  Although the aardwolf is observed hanging around carcasses,
there are conflicting reports over whether it eats carrion, or is
merely in search of maggots and carrion beetles.




Cheers

Tim





Cheers

Tim