Re: Psittacosaurus bristles

["Steve Brusatte" <dinoland@lycos.com>]

On Thu, 18 Jul 2002 19:58:46  
 Waylon Rowley wrote:
>Steve  Brusatte wrote:
>> And, is it discussed how these filaments might
>> parallel the series of ossified tendons seen in the
>> tail?  I'm certainly not suggesting that they are
>> ossified tendons, but I find it interesting that in
>> some _Psittacosaurus_ species said tendons only
>> extend along the proximal half of the tail.  Likely
>> coincidence, but perhaps there is a functional
>> correlate??
>
>Strong back + bristles *might* indicate a defensive
>use.

Well, that's a possibility, certainly.  In _Psittacosaurus_, the ossified 
tendons stop short of the tail in all species but _P. xinjiangensis_ (where 
they extend onto the proximal half of the tail).  So, although ossified tendons 
are primitive for Ornithischia, their role in _Psittacosaurus_ was different 
than in, say, _Tenontosaurus_.  A strengthening of the back, not the tail, 
seems to be a primary function.

Rob Gay wrote:
>There was a talk at Bozeman (IIRC) about functional limits of supporting
   tendons, where they would be effective, and where they wouldn't be. Very
   interesting talk, and I wouldn't be surprised if that played into the
>placement of tendons on Psittacosaurus specimens..
  
I didn't hear this talk, but I believe I read a summary of it.  Is this the 
talk that discussed how, in most cases, the ossified tendons actually were used 
to keep the tail stiffer dorsoventrally rather than laterally?  Maybe the 
tendons in _Psittacosaurus_ helped keep its back stiffer, while the modified 
tendons in _P. xinjiangensis_ were perhaps tied to a new functional role of the 
tail? Interesting to speculate.

Steve

-----
The Chicago Sun Times reported yesterday that Cher was granted a special tour 
of the Sue exhibit at the Field Museum.  Alongside the tidbit on Cher was a 
short article-only a few sentences-on the new pterosaur, sadly proving Tracy 
Ford's hypothesis that celebrities garner more attention than fossils (although 
Cher is a fossil in her own right). :-))
-----

---
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