Re: Status of _Caudipteryx_

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

ELurio@aol.com wrote (in reply to Mickey Mortimer's post):

> << The whole secondarily flightless bird hypothesis is supported mainly by 
> the
> birds aren't dinosaurs crowd who like it because a feathered dinosaur would 
> ruin their phylogeny, >>
>
> Not really, primarily flightless birds work quite well, especially for the
> early cretaceous.

Yes really.  By "primarily flightless" I suppose you mean that such birds 
are primitively flightless and did not evolve from volant (flying) ancestors 
- which would make _Caudipteryx_ *secondarily* flightless.

Feduccia and friends are claiming just that - that_Caudipteryx_ is indeed 
secondarily flightless (_Caudipteryx_ is a "Mesozoic kiwi" in their words).  
However, cladistic analyses (see previous post) indicate that _Caudipteryx_ 
evolved from outside the Aves, indicating that it was "primarily" 
flightless.  This puts a spanner in the works where Feduccia and others are 
concerned, since they cannot abide the idea that there might have been 
flightless, feathered nonavian theropods.  A "feathered dino" would indeed 
ruin the phylogeny proposed by Feduccia - which essentially states that 
birds evolved from outside the dinosaurs (exactly from WHAT Feduccia hasn't 
actually said).

There are flightless birds in the Cretaceous (hesperornithiforms, 
_Patagopteryx_, _Gargantuavis_, possibly alvarezsaurids which are flightless 
but not avian according to Sereno).  For these taxa, both their inclusion 
among the birds and their secondary flightlessness is inferred from their 
skeletal anatomy.  The presence of feathers in _Caudipteryx_ doesn't 
automatically include this genus in the Aves (contra Feduccia).  
_Caudipteryx_'s skeletal anatomy strongly suggests that this creature is a 
nonavian theropod, probably an oviraptorosaur).  Although, like Adam Yates, 
I am very interested in Elzanowski's notion that ALL oviraptorosaurs are 
secondarily flightless birds.


Tim



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

Dr Timothy J. Williams

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

Phone: 515 294 9233
Fax:   515 294 3163

_________________________________________________________________
Get your FREE download of MSN Explorer at http://explorer.msn.com