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



On Mon, May 2nd, 2011 at 11:01 AM, Tim Williams <tijawi@gmail.com> wrote:

> Dann Pigdon <dannj@alphalink.com.au> wrote:
> 
> 
> > Sure - but that would require specialised claws and digging physiology, 
> > which would make it
> more
> > difficult to run from danger. At the moment the aardwolf is specialised 
> > enough to be able to
> subsist
> > largely on termites, but not so specialised that it can't run like the 
> > clappers when it needs
> to.
> > Whereas the aardvark doesn't have the luxury of speed to escape danger. The 
> > even more
> > specialised giant anteater is slower yet again.
> 
> 
> All true.  Nevertheless, the giant anteater can use its massive
> foreclaws as a weapon when confronted, typically by adopting a
> bipedal/tripodal posture.  Jaguars are known to fall afoul of an
> anteater's claws.
> 
> 
> To return to dinosaurs, this is how I imagine therizinosaurs used
> their foreclaws.  If you can't be fast, be formidable.

That's all fine and dandy *after* you have acquired massive muscles and claws, 
but I wonder how 
often myrmecophages actually make it past the 'hump' between having no digging 
specialisations 
but fast locomotion, and developing highly specialised digging equipment that 
can also compensate 
for the reduced locomotor abilities. It would seem that the in-between states, 
where you can't quite 
run fast enough to avoid predators, but also don't quite have the right 
equipment to fend them off, 
would be a very vulnerable point in their evolution.

Echidnas seem to have managed it by developing defensive spines, but I can't 
help but wonder 
whether the giant anteater evolved its current form during a time when large 
predators were rare 
in their environments. Then again, aardvarks seem to be in that in-between 
phase at the moment. 
Perhaps in their case being largely nocturnal and sheltering in burrows has 
compensated for their 
lack of speed and power (although they *will* attack using their claws as a 
last resort).

-- 
_____________________________________________________________

Dann Pigdon
Spatial Data Analyst               Australian Dinosaurs
Melbourne, Australia               http://home.alphalink.com.au/~dannj
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