Re: Young Allosaur feathers?

["Tim Williams" <twilliams_alpha@hotmail.com>]

Jordan Mallon <j_mallon@hotmail.com> wrote:

> Correct me if I'm wrong, but so far as I know, we have no evidence for any 
> form of integument in _Coelophysis_ at all.  Not feathers.  Not scales.  So 
> unless we are able to prove (or "support the hypothesis," as my lab 
> coordinators would have me say) that _Coelophysis_ had scales, there's no 
> reason to believe that it couldn't have feathers.

You're right: there's no reason at all that _Coelophysis_ did NOT have 
feathers.  However... there's no direct evidence that any theropod taxon 
more basal than Maniraptoriformes had a feather-like body covering.  All 
fuzzy and feathered theropods so far discovered belong to this clade.  All 
non-maniraptoriform dinosaurs so far discovered have a scaly or tubercular 
epidermis: tyrannosaurs, abelisaurs, sauropods, ornithischians.  (Even the 
spiny-tailed psittacosaur shows no evidence of dino-fuzz over the rest of 
its body.)

Applying the principal of phylogenetic bracketing, we're going out on a limb 
in suggesting that _Coelophysis_ (a basal neotheropod) did have a feathery 
body covering.  Nature does throw us a curve ball every now and again, e.g. 
the presence of feather-like integument in _Sinosauropteryx_, but not in the 
closely related _Compsognathus_.  But overall, the principal of phylogenetic 
bracketing should be upheld until contrary evidence turns up.  Therefore, 
the most *parsimonious* interpretation is that _Coelophysis_ was not covered 
in fuzz.  But the discovery of a feathered herrerasaur would change 
everything.




Tim



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