Re: Crown groups

["T. Michael Keesey" <mightyodinn@yahoo.com>]

--- "Jonathan R. Wagner" <jonathan.r.wagner@mail.utexas.edu> wrote:
> "... Tim Rowe pointed out that [the Pan- convention] means that even a
> non-expert will be able to quickly and concisely associate name with
> definition. Assuming you know the accepted "higher" names for at least one
> taxon containing every extant species (not too bad, since most of it can be
> swept into Archaeobacteria and Eubacteria, you can actually give a taxon
> name for almost any fossil form without knowing ANY of the fossil taxonomy.
> I hate to say it, but I find this compelling."
> 
> So it may be unpleasant to give up Synapsida, but we gain the ability to
> more effectively communicate with people who weren't familiar with the term.
> Is it worth it? I'm not entirely sure. After all, "they" are already getting
> crown clades, maybe paleontology should get to keep something!

Why should one form of definition require an affix when others don't? Why don't
we have affixes for crown clades, too? If there's a _Pancrocodylia_, why not a
_Coronocrocodylia_, too?

Answer: It would be too disruptive!

However, I grant you that it would be nice to tell, at a glance, what type of
taxon something is. What's the solution? Surprisingly, the best answer may be
found in the Linnaean system....

How can we tell, at a glance, that Animalia is a kingdom, Saurischia is an
order, and Glires is a cohort? We can't, if they're written that way. But, if
they are written as Kingdom Animalia, Order Saurischia, and Cohort Glires (as
they frequently have been), it's easy! (In fact, even easier than telling that,
say, "Panamniota" is a panstem clade.)

So, why not have the same option in phylogenetic taxonomy? Panstem Clade
_Synapsida_, Crown Clade _Mammalia_, Stem Clade _Saurischia_, Node Clade
_Dinosauria_, Apomorphy Clade _Avialae_, etc. Not mandatory, but optional for
the first mention of a clade, or in the systematics section of a paper (much as
rank designations are in the Linnaean system). That way we can keep the old
names, but mark what the new definitions are.



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