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Date: Sat, 23 Jun 2001 14:09:53 -0600 (MDT)
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 <email@example.com> 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.