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

Jason Brougham <jaseb@amnh.org> wrote:

> The thing is that the alvarezsaur forelimbs are highly specialized. In our
> minds, a priori, it seems this should correspond to a  highly specialized
> ecological niche, right?

I'm not sure I agree.  When the forelimbs ceased to be used for any
predation-related function (like catching or holding prey) - what did
the theropod do with them?   If alvarezsaurs continued to hunt small
prey on the ground, then the forelimbs were likely of little use.  But
if myrmecophagy was also part of the alvarezsaur's behavior, then the
forelimbs could have become specialized for this purpose alone
(tearing open nests or wood), even if termites or ants were only a
relatively minor part of the overall diet.

In short, the alvarezsaur forelimbs took on an auxiliary function.
This would also explain the stunted nature of the forelimbs
(reflecting their reduced trophic role), as well as their impressive
musculature (necessary for tearing into nests or wood).  So although
the forelimbs were specialized, the ecological niche of alvarezsaurs
was not.  At least, that's the way I see it.

> The aardwolf is not morphologically specialized,
> so its more general diet fits this impression.

It's my understanding that termites comprise most of the aardwolf's
diet, and it is regarded as myrmecophagous more so than omnivorous.
However, it feeds mostly on exposed termites - principally harvester
termites, which forage at the soil surface and can teem in humongous
numbers.  So the aardwolf doesn't need to do much digging, and its
head remains down close to the ground.  The combination of weak cheek
teeth, large canines, and strong masticatory musculature suggest the
jaws can be used for defense, and for killing small vertebrates.