RE: Dinosaur Feathers (was RE: Bambiraptor complete!)

["Williams, Tim" <TiJaWi@agron.iastate.edu>]

Eric Lurio wrote:

>If they resembled a kiwi's they'd be avian. 
and
>"Dinosaur" plumage WAS avian.  

Absolute tosh.  The feathers of kiwis (_Apteryx_) are not "typical" bird
feathers, which are planar, pinnate and arranged to provide optimal
aerodynamic performance.  And it doesn't really matter that the kiwi's
feathers are not "typical".  The hair-like things that kiwis possess are
nevertheless called feathers, because: (1) they conform to the basic
structure that is diagnostic for feathers; (2) based upon the phylogenetic
position of kiwis, there is no reason to dispute the homology of these
structures to "typical" feathers.  Thus, the identity of the kiwi's
integumental structures as feathers is assured - and entirely separate from
the independent evidence that assigns _Apteryx_ to the Aves.

The integumental appendages we see in _Sinornithosaurus_, _Microraptor_,
_Caudipteryx_, and _Protarchaeopteryx_ conform to both (1) and (2).  Putting
all feathered theropods into the Aves simply because their integumental
appendages "look like" the feathers of modern birds is absurd.

Eric's post is an example of the pitfalls of clinging to a strictly
typlogical framework for defining what is and isn't "avian".  For some
reason, feathers appear to imbued with extra significance when sorting
fossil taxa into a phylogeny.  You know, if _Archaeopteryx_ had not been
found with feathers attached, does anyone truly believe that it would have
been classified among the birds?  _Archaeopteryx_'s skeleton does not "look
like" the skeleton of a modern bird - in this (and in so many other things)
Ostrom was dead right. 




Tim