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Re: Young Allosaur feathers?




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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