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RE: Sinosauropteryx feathers?



Rutger Jansma wrote:

> Some while ago, HP Oyvind M. Padron posted a similair message and I 
> completely agree with him and with HP Tim Williams that each taxon 
> should be evaluated seperately and that one should not restore any 
> animal with feathers untill the evidence becomes available. 

No no no no.  This isn't what I said at all.  The presence of feathers
should be treated phylogenetically.  In other words, feathers should be
treated as a normal phylogenetic character.  Each taxon should be assessed
as "probably feathered" or "probably not faethered" based on their position
in theropod phylogeny.  

This is the rule of thumb that applies to any other theropod character.  We
don't give _Alioramus_ a sickle-claw on its second toe because (1)there's no
evidence that the common ancestor of eumaniraptorans and tyrannosaurs had
this faeture; and (2) other tyrannosaurs for which pedal elements are known
do not have this feature.  However, if we discover the skeleton of a
dromaeosaurid lacking hindlimb elements, one would be quite confident in
reconstructing it with a sickle-claw on its second toe, even in the absence
of direct fossil evidence.


>If we do find a specimen of Sinovenator, or any other Troodontid, with 
> feathery intugement or a similair body covering, I'll accept that they 
> were feathered, no problems, but untill there is no evidence for this, 
> Troodontids should be restored featherless.

Current phylogenies place troodontids and dromaeosaurids in the
Deinonychosauria and regard the Deinonychosauria as the sister taxon to
Aves.  Dromaeosaurids (at least the basal ones) show feather-like
integumental structures.  Birds (of course) have feathers.  Thus, using the
principle of phylogentic bracketing, troodontids _should_ be restored with a
feather-like body covering.  The _exact_ type and distribution of
feather-like covering requires a little more imagination, however.

Rutger, you're right on one point: feathered theropods do look cool! :-)



Tim