RE: naked heads (was: Re: Velociraptor Animation)

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

Luc Bailly wrote:

> I don't think so. I see feathers on the top of the skull of this
> wonderful fossil, so I _do_ think cf. _Sinornithosaurus_ had a 
> feathered head, and I also think the same for many little dromaeosaurs 
> and troodontids, but AFAIK there's no evidence of a feathered head in 
> _Velociraptor_, _Deinonychus_,

I may be missing something here, but there's no direct evidence of feathers
from any part of the body in _Velociraptor_ or _Deinonychus_.  We don't have
integument preserved in specimens of either of these genera AFAIK.
Velociraptorines have been reconstructed with feathers based on the
principal of phylogenetic bracketing: the common ancestor of birds and
dromaeosaurids were feathered, so we assume all descendents of this ancestor
were feathered until proven otherwise.

> why not some dromies with a feathered head like _Falco_ and others with 
> a naked head like _Gyps fulvus_.

Why not indeed?  Naked heads are not so much associated with scavenging per
se, but (as Jaime and I noted) it is correlated with scavengers that plunge
their heads deep into carcasses.  It's a messy business, so best not to have
any more feathers than necessary fouled by blood and gore.



Tim

------------------------------------------------------------ 

Timothy J. Williams 

USDA-ARS Researcher 
Agronomy Hall 
Iowa State University 
Ames IA 50014 

Phone: 515 294 9233 
Fax:   515 294 3163