Re: Theropod Forelimb Reduction

[Tim Williams <tijawi@yahoo.com>]

 Nicholas Renaud <syntarsus@yahoo.com> wrote:


> After reading the new Raptorex paper,
> I was wondering if anyone knows of a specific reference
> discussing the hypothesis that forelimb reduction is
> correlated with increasing body size? For example, this
> trend is potentially present in tyrannosaurids in which
> small forelimbs are a result of large body size.


Hmmm... didn't the _Raptorex_ paper argue that forelimb reduction came *before* 
the increase in body size in tyrannosauroid evolution?


An hypothesis similar to the one you mention was raised in a chapter of the 
book "Tyrannosaurus rex, the Tyrant King" by Lockley, Kukihara and Mitchell. 
("Why Tyrannosaurus rex Had Puny Arms: An Integral Morphodynamic Solution to a 
Simple Puzzle in Theropod Paleobiology").  The authors argued that 
tyrannosaurids had small forelimbs simply because
they had such large heads (due to "the morphodynamic compensation between head 
and forelimbs").  I don't buy it myself, and I don't expect this hypothesis to 
garner much support.


BTW, forelimb reduction is very prevalent among theropods, both small and 
large, avian and non-avian.  


Cheers

Tim