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Date: Sat, 23 Jun 2001 14:09:53 -0600 (MDT)
From: kinman@usa.net
To: phylocode@ouvaxa.cats.ohiou.edu
Subject: Crown groups mainstream?
Dear All,
To say that a crown group Mammalia is "mainstream" is perhaps a bit =
of
Ivory Tower tunnel-vision and/or wishful thinking. Just because McKenna =
and
Bell recognize such a crown group doesn't mean it is "mainstream" or like=
ly to
become so.
Most mammalogists still seem to think that a Mammalia which is
cladistically anchored on a monotreme (which still have a miserable fossi=
l
record) is a dumb idea. They continue to recognize a Mammalia sensu lato=
,
which has been given a separate clade name Mammaliformes (or is it
Mammalimorpha?---well, it doesn't really matter because few mammalogists =
use
such names anyway).
I would very HIGHLY recommend that PhyloCode workers NOT define Mam=
malia
as a crown group, because there is a good chance it will end up excluding=
multituberculates, and it will certainly exclude sinoconodonts,
morganucodonts, and docodonts (all of which have the well-known mammalian=
jaw
and three ear ossicles). =
I think it is pretty obvious a crown group Aves has been rejected
already, and who knows what might happen to a crown group Archosauria, be=
cause
pterosaurs may not be the only group that gets ejected from that taxon. =
It is
perhaps still the best hope that some large crown group within amniotes w=
ill
become mainstream, but I wouldn't even bet on that one. Crown groups see=
m to
cause more problems than they solve, and if I was a paleontologist I thin=
k I
would dislike them even more.
--------Ken Kinman
P.S. By the way, I think Mike's dinosauricon is great, and it is very we=
ll
organized and thought out (even if it does have a crown group Mammalia an=
d a
few other PT-inspired drawbacks). =
****************************************
David Marjanovic <david.marjanovic@gmx.at> wrote:
> A few points from the Marjanovic/ Headden conversation I thought I'd tr=
y
to
> clarify:
>
> 1) The idea of a crown clade [...] There
> are multiple ways to define one, including picking representative speci=
es
> (note that the code DOES recommend specific specifiers, as opposed to
> "higher" taxa).
True, I didn't use this in my post because "higher" taxa have "historical=
ly"
been used in such definitions, and I don't know the type species of all t=
he
genera I mentioned.
> 3) Mike Keesey is a nice fella, but his website is not, in my opinion, =
a
> PhyloCode resource. [...] Whether his systematics conform to those
published
> in the
> literature or not is a matter to be investigated BEFORE his material is=
used
> as a point of argumentation. [...] and it may be difficult for
nonspecialists
> to separate Mike's ideas from those which are published.
All true, I have cited his website because 1. everyone on this list can
immediately have a look without spending hours in libraries and 2. it lis=
ts
lots of synonyms, and definitions for many clades, so it is quite suitabl=
e
to illustrate what I was talking about.
Perhaps I should rephrase -- should the disputes over crown groups left a=
t
the individual cases, where they are now*, or should they be concentrated=
in
one spot =3D Recommendation?
*The Dinosauricon is current mainstream in using Mammalia and Archosauria=
,
but not Aves, for crown groups. Though "mainstream" only means something
like 60 -- 70 % of those that work on these groups, I guess.