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Re: Deinocheirus (was Sauropodz r kewl WAS: silly conversation on 2012 US presidential race)

Thomas R. Holtz, Jr. <tholtz@umd.edu> wrote:

> Having held the claws (well, casts) of Deinocheirus, they are bigass, but 
> they aren't really fearsome. Now a Torvosaurus or
> spinosaurid or megaraptoran claw: THOSE are scary nasty!

Nevertheless, the claws of _Deinocheirus_ could have been a wicked
deterrent against a predator approaching too closely.

> (I'm quite fond of making the therizinosaur-ground sloth analogy, and before 
> me Russell & Russell did the therizinosaur-chalicothere
> analogy. Hard to disprove, as we can't directly observe the behavior of 
> either member of the pair... :-S

I had reasoned that the hand-claws of therizinosaurs (at least in the
more derived species) were used predominantly for defense.  After all,
it's not like these pot-bellied theropods could run from danger.  And
especially in _Therizinosaurus_ the claws do not seem to be the right
shape for grasping or hooking branches.  I like Robert's description
of them as "freddy-kruger hands".

The forelimbs of _Deinocheirus_ and _Gigantoraptor_ might have been
used in the same way - as defensive weapons.  In the transition from
carnivory to herbivory it might have been useful to retain long,
clawed forelimbs for defense.  Though _Gigantoraptor_ was fairly
cursorial for its size, and the same might have been true for
_Deinocheirus_ if it arose from ornithomimosaur stock.  But the larger
therizinosaurs probably had no choice but to hold their ground.