RE: Titanis paper?

[Tim Williams <twilliams_alpha@hotmail.com>]

Eike wrote:

> "Grasping arms" was always a very loose
> interpretation. What is plausible is basically the
> situation found in "spur-wristed" birds (Anhimidae.
> _Plectopterus_, _Pezophaps_, _Vanellus_ spp. etc)
> taken one step further, resulting in "merely"
> extraordinarily flexible wings (for a flightless
> bird).

I'm not saying you're incorrect, but my impression of _Titanis_ is a little 
different.  The shape of the proximal part of the major wing digit suggests 
that this digit was mobile, which has led to speculation that this digit might 
have sported a claw.  AFAIK, no wing-claws (spurs are otherwise) are known for 
_Titanis_.  

> These might have helped in holding down largish prey.
> Of all the business ends of a phorusrhacid, the wings
> had the shortest reach after all. So for tackling
> whatever prey could be handled by the beak or feet,
> the wings would not have been useful anyway because
> they'd hardly have made contact after all was said and
> done.

_Titanis_ is only known from fragmentary material*, and the ideas about its 
ecology are highly speculative.  The idea that _Titanis_ was a formidable 
predator is based on (a) its large size, (2) phorusrhacid affinities; (3) 
mobile wing phalanx.  Its presumed predatory habits has led to the idea that 
its forelimbs were somehow used in predation, in a manner comparable to 
tyrannosaurids.  But like I said, this is highly speculative. 


* Hypodigm (after Alvarenga & Hofling, 2003): Distal portion of the right 
tarsometatarsus (UF-4108) (holotype); phalanx 1 of digit III (UF-4109) 
associated (?) to the holotype; phalanx 1 of digit III (TMM-43060-115); 
proximal extremity of the left tibiotarsus (UF-7333); complete left 
carpometacarpus (UF-30003, Fig. 6A); two complete cervical vertebras (C2 and 
C3); the proximal portion of the right fibula, phalanges 1, 2 and 3 of the left 
digit III and two phalanges 1 of digit IV (left and right) (UF wt/n.).

Cheers

Tim
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