Re: Haplocheirus does not confirm alvarezsaurs are maniraptoran

[Tim Williams <tijawi@yahoo.com>]

David Marjanovic <david.marjanovic@gmx.at> wrote:


> Ant-eaters don't need reach. (They can just walk closer.)
> They only need power.


I'm coming round to thinking that you're probably right here.  The giant 
ant-eater uses its fore-claws to make a small breach in the ant or termite 
nest, then feeds on the insects that stream out.  However, the ant-eater 
doesn't feed at any nest for too long: the ant-eater soon backs off to avoid 
the soldier caste.  The ant-eater rarely destroys a nest, but survives by 
ingesting a relatively small number of insects from a large number of nests.


So alvarezsaurs could have fed the same way.  Breach the nest (or 
insect-infested wood), slurp up some emerging insects, then run away before the 
angry colony launch a full-scale attack.  Or maybe it breached trees to access 
the sugar-rich sap - a much better food source than ants or termites.  And sap 
doesn't bite. 

 
> The trick is that all extant ones are (to varying degrees,
> but still) quadrupedal. To be useful in locomotion,
> forelimbs need a minimum length. Compromises result that the
> bipedal alvarezsaurids simply didn't need.


Nevertheless, a short reach would limit the alvarezsaur to breaching nests or 
trees that were shoulder height (or lower), rather than head height.  I still 
think you're right though.


Cheers

Tim