Re: Heterodontosaurid with protofeathers

[Tim Williams <tijawi@yahoo.com>]

Mike Keesey wrote:


> I'm not sure I see a problem that needs fixing here,
> though. What else would the name "Avifilopluma" refer to? It doesn't
> make any sense to give that particular name a node- or branch-based
> definition. And if you don't have a use for the name ... don't use it!


No, I wasn't saying that Avifilopluma should be converted to a node- or 
stem-based clade.  I was only making the point (said many times before) that 
having a clade founded on an integument-based apomorphy (as Avifilopluma is) is 
fraught with danger, given the vagaries of the fossil record.


David Marjanovic wrote:

> In a sense it is: if the name doesn't refer to anything
> that's similar to the concept that's historically associated
> with it, it's good if it self-destructs, because that means
> it's associated either with more or less the same concept or
> with nothing at all.


Thanks - yes, that's the precise issue I was getting at.  In the unlikely event 
that either saurischians or ornithischians are found to be closer to 
crocodylians, then under the current definition (_Triceratops_ + _Passer_) 
crocodylians and a lot of other taxa would find themselves inside Dinosauria.  
This would go against the grain of the traditional usage of "dinosaur".  The 
addition of qualifying clauses (such that _Crocodylus_ etc cannot be included 
in Dinosauria) would ensure that Dinosauria would cease to exist as a taxon 
(i.e., self-destruct).


Cheers

Tim