Re: PhyloCode Discussion: Crowns, Panstems, and their Correspondence to each oth

[Tim Williams <twilliams_alpha@hotmail.com>]

T. Mike Keesey wrote:

> "EXTANT"
>
> This has been discussed before, and is mentioned in Note 9.4.1, which 
> states
> that the author should clarify their exact meaning for the word "extant". 
> It
> seems to me it may be preferrable for the code to define a consistent 
> meaning.
> The most stable and easily applicable definition I can think of is "living 
> and
> published at the time of the definition's publication", but I'd certainly 
> like
> to see others' suggestions.

This is something I hadn't considered before.  Sadly, many groups at the 
level of "family" and "order" have become extinct in last few hundred years: 
e.g., birds (Dinornithidae, Aepyornithidae, Raphidae [probably nested within 
Columbidae]) and mammals (Thylacinidae, Nesophontidae).  Under the above 
definition, these would no longer be considered "crown groups".

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