[Taxacom] early extant angiosperms

[Barry Roth]

HI, Ken,

Not being a botanist, I can't comment on the individual taxa involved, but only on the principles.  Perhaps "basal dicots" (or the like) is a useful, informal, descriptive term.  There will always -- by definition -- be "basal dicots," but the membership of that group (or, rather, our understanding of it) will vary depending on the phylogeny accepted at a given time.  This is not what you want to happen with a formal taxon name.  So yes, I think we arrive at the same conclusion, just by different routes.
 
Barry

--- On Sat, 2/20/10, Kenneth Kinman <kennethkinman at webtv.net> wrote:


From: Kenneth Kinman <kennethkinman at webtv.net>
Subject: Re: [Taxacom] early extant angiosperms
To: taxacom at mailman.nhm.ku.edu
Date: Saturday, February 20, 2010, 7:13 PM


Hi Barry,
     Well, yes and no.  It is clearly probable that we will find
evidence of a small branch below Amborellales, either extant or perhaps
more likely fossil.  However, this is more a problem of using
"basalmost-xxxx", not "basal-xxxx".  The new branch would change the
meaning of the "basalmost-xxxx", but "basal-xxxx" could simply be
appended as the new basalmost clade of "basal-xxxx".   
       The main reason I am now leaning against calling my Class
Magnoliopsida "basal dicots" or "basal angiosperms", is not because of
potential new discoveries of basalmost members, but because of the
varying usages of "basal dicots" or "basal angiosperms" at the upper
end, whether people variously cut it off after Amborellales, or after
the ANITA group, or at the base of eudicots, or somewhere in between.
The term basal therefore seems more problematic where the group ends,
not where it begins.
      The more I think about it, the more I am leaning toward
paleodicots (or the alternative spelling palaeodicots).  It is a nice
simple word which is complementary to eudicots (which are exgroup to the
paleodicots).  I think the base of the eudicots is now almost
universally agreed upon, and being also the upper end of the
paleodicots, the latter term has less baggage than using the phrase
"basal dicots" or "basal angiosperms".   So I think we agree, but for
slightly different reasons.
        -----Cheers,
                    Ken
----------------------------------------------------

Barry Roth wrote:

In any case I would vote against "basal-xxxx" because it would only take
interpolation of one small branch below them to make them not basal any
more.  I suppose a larger principle would be not to name groups with
respect to their position in a phylogeny, since our understanding of
phylogeny is fluid.   Barry

--- On Sat, 2/20/10, Kenneth Kinman <kennethkinman at webtv.net> wrote: 
From: Kenneth Kinman <kennethkinman at webtv.net> 
Subject: Re: [Taxacom] early extant angiosperms 
To: taxacom at mailman.nhm.ku.edu 
Date: Saturday, February 20, 2010, 5:11 PM 
Hi Steve, 
      Thanks for the input.  It made me think of a fourth
alternative: 
"early-divergent dicots".   And today I also remembered a fifth 
alternative: paleodicots (palaeodicots)--- which would have the
advantage of being just one word, and also having been used by various
botanists for a longer period of time.  
     It also would more readily indicate that the old dicot
Class has been divided into two separate classes, Class Magnoliopsida
(paleodicots) and Class Rosopsida (eudicots).  On the other hand, both
"basal" and "early-divergent" have been applied to more restricted
groups at the base of the paleodicots. 
         --------Cheers, 
                         Ken 
-------------------------------------------------------- 


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