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





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> Date: Mon, 2 May 2011 12:43:48 +1000
> From: tijawi@gmail.com
> To: dinosaur@usc.edu
> Subject: Re: Alvarezsaur spurs (was Re: dino-lice)
>
> Dann Pigdon wrote:
>
> > 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.
 
> But to return to your point - this wouldn't be relevant to the
> aardwolf or aardvark, both of which appear to have evolved their
> myrmecophagous adaptations on terra firma (this is true even if the
> tubulidentates evolved from arboreal ancestors). In the absence of
> some form of armor (as developed by armadillos, echidnas and
> pangolins) or enlarged and highly formidable foreclaws (as in the
> giant anteater), a large myrmecophagous mammal is very vulnerable on
> the ground, and there is a cost associated with specialized fossorial
> forelimbs in the reduction of terrestrial mobility.
 
 and for bipeds (such as Alvarezsaurs), it may be a cost they simply cannot 
afford.
 

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> Date: Mon, 2 May 2011 11:59:14 +1000
> From: tijawi@gmail.com
> To: dinosaur@usc.edu
> Subject: Re: Alvarezsaur spurs (was Re: dino-lice)
>
> Augusto Haro wrote:
>
> > I never heard of the term cursorial not being applied to animals
> > because they are not active during winter. I would certainly label it
> > as cursorial because of its limbs proportions, very similar to those
> > of other hyenids and canids.

> Sorry Augusto - I didn't intend to refute your suggestion that the
> aardwolf is cursorial. However, the alvarezsaur anatomy doesn't fit
> with the notion that it had a particularly aardwolf-like ecology, and
> lurked in a burrow much of the time when its preferred food (termites)
> became scarce. To me, the aardwolf analogy for alvarezsaurs extends
> mainly to two aspects: evolution from within a clade of devout
> carnivores (Carnivora, Theropoda); and the ability to take in food
> items other than just ants or termites (which, as David said, is a
> characteristic of many myrmecophagous mammals - it's all a matter of
> degree).
 
I think there's a third similarity you skipped over:  that both Ardwolves and 
Alvarezsaurs have preferred to focus on the ability to "run away! run away!" 
very quickly, over having Therizinosaur-like defenses.