Re: Why did small dinos become extinct?

[David Marjanovic <david.marjanovic@gmx.at>]

> The hands of alvarezsaurids faced ventrally, not medially, based on 
> Senter's 2005 study on _Mononykus_'s forelimbs (Paleobiology 31: 373-381).

Oh, yes -- but that's because the arms are fixed in a sprawling position. 
Imagine a bird with permanently spread wings.

> I also like the alternative idea of alvarezsaurids being professional 
> scavengers - using their stubby clawed forelimbs to rip into carcasses, 
> gobbling up the yummy bits, and using their long legs to run away when a 
> bigger predator came along.  Having only a single big claw on each 
> forelimb, sheathed in keratin, might also have decreased the risk of 
> infection from a putrefying carcass.

Then I'd expect more of a cutting edge on the claw, and longer arms. Or 
simply sharp teeth. Alvarezsaurid arms had a very small range of motion 
(same paper); they had nothing but sheer power.

Besides, professional scavengers that can't fly are impossible, see 
*Tyrannosaurus*.