Re: Heterodontosaurid with protofeathers

[Tim Williams <tijawi@yahoo.com>]

Mike Keesey wrote:


> Well, if shifting or uncertain content = "danger", then
> phylogenetic
> nomenclature may not be your cup of tea, anyway.


I have nothing against PN.  Quite the opposite.  PN is my system of choice, and 
I much prefer it to rank-based classifications (phylum, class, order... etc).

I'm only picking on apomorphy-based clades.  Look at Avifilopluma:

"The clade stemming from the first panavian with feathers homologous with those 
of Aves ... feathers referring to hollow-based, filamentous, epidermal 
appendages produced by follicles."

Are the epidermal filamentous structures seen in _Tianyulong_ and/or pterosaurs 
homologous with feathers?  The content of Avifilopluma hinges on this question. 
 The content is not just in flux because of topology (as in stem- and 
node-based clades), but homology as well.

If the "dinofuzz" of _Tianyulong_ and the "pterofuzz" of pterosaurs like 
_Sordes_ is NOT homologous to bird feathers, then the Avifilopluma would be 
limited to maniraptoriform theropods.  But, if either integument is homologous 
to bird feathers, then Avifilopluma could be expanded to include ornthischians 
(Avifilopluma=Dinosauria) and/or pterosaurs (Avifilopluma=Ornithodira).


> That said, your example still holds, but you wouldn't have
> to give _Dinosauria_ a qualifying clause if you just established
> that the name _Archosauria_ has priority for Clade(_Crocodylus 
> niloticus_ + _Vultur gryphus_) (or whatever).


True.  But what's the harm in including a qualifying cause?  That means the 
definition of Dinosauria is self-contained, and doesn't need recourse to other 
definitions (such as that for Archosauria).


Cheers

Tim