User talk:Peter M. Brown/Michel Laurin updates

Michel, it would be convenient if you would paste the wikitext for the entire section in the user page, the lead for Lissamphibia in the case of your latest text; I can compare that with the live version to see just what change you want.

I also have a problem with your specific proposal, as it seems to be saying that the mere existence of a stem-batrachian is evidence for lissamphibian polyphyly. If, however, the phylogeny is like this

Lissamphibia	Gymnophiona Albanerpeton Batrachia Anura Urodela

then there is a stem-batrachian, Albanerpeton in this case, but Lissamphibia is monophyletic. To me, anyhow, it isn't clear from what you have suggested adding that the position of Gerobatrachus hottoni is any different. Peter Brown (talk) 00:27, 9 December 2012 (UTC)

Hi Peter,

Before I paste the text, let's discuss this first. Perhaps what I need to mention is that Gerobatrachus hottoni is a temnospondyl. The concept of a monophyletic Lissamphibia has always been that it excludes any Paleozoic taxon. Albanerpetontids are more recent and have generally been thought to be lissamphibians, so their location in the tree where you place them does not make Lissamphibia paraphyletic. But given that Gerobatrachus is from the Early Permian and part of a group that has never been included in Lissamphibia before (even Doleserpeton was thought to be outside, even if an immediate sister-group, in Bolt's proposal). I am unsure how much of that information should be included there; I am open to your suggestions.

That might fit better in the section on relationships and definition. If so, the text in the introduction could simply state: Recently, the Early Permian dissorophoid Gerobatrachus hottoni has been argued to represent a stem-batrachian . However, the position of this taxon is uncertain; it may also be a stem-tetrapod. If you agree with this proposal, I will paste the revised texts of the two entire sections concerned. Thanks,

Michel Laurin (talk) 07:45, 9 December 2012 (UTC)

I am finding this very difficult to understand, and I am sure that the general reader will fare no better. Marjanović & Laurin (2009) say (p. 336) that three approaches "all hint at a Permian or (less likely) a Late Carboniferous origin of Lissamphibia." If lissamphibians started out in the Permian or Carboniferous, though, then Paleozoic species cannot be excluded from the taxon by definition.

The third paragraph of the lead (what you call the introduction) is poorly written. It says that the extant orders "evolved from a common ancestor and so form a clade." However, any group of animals, those weighing over 10 kg for example, evolved from a common ancestor; nothing very interesting follows. I'm not sure that the lead can usefully be augmented without being rewritten.

If you are going to modify the lead, do observe the guideline at MOS:INTRO: Where uncommon terms are essential, they should be placed in context, linked and (if possible) briefly defined. "Uncommon", I think, means unfamiliar to persons likely to be reading the article. I don't think, for example, that this edit of yours should have used the word "monophyletic" without a definition, especially as term is introduced later in the Reptile lead in a more accessible way to make really the same point that you were making.

Peter Brown (talk) 19:36, 9 December 2012 (UTC)

Hi Peter. I agree with what you wrote (so do feel free to reformulate what I wrote about Reptilia in the monophyletic sense; I just thought that readers had to be made aware of this important conceptual shift). I am still discovering various guidelines and conventions of Wikipedia. The Lissamphibia page has so many problems that fixing them all would require a thorough re-write which, given Wikipedia's complex procedure and my particular position in it would be extremely time-consuming to tackle. Till we get to this, over the next months or years, if ever, because I won't be able to keep devoting Wikipedia as much time as sorting the various policy and conflicts has taken me (or you), how about just removing that erroneous statement about Gerobatrachus implying a younger age of origin of Lissamphibia than implied by molecular studies (that is simply wrong, as another user pointed out on the talk page), and mention that the position of Gerobatrachus has been questioned by Marjanovic & Laurin (2009)? The evidence is in a long SOM (Supplementary On-line Material) of the paper, which I can send you by e-mail, if you wish (it is also available on the journal's web site, but you have to pay to get it, as we discovered after publishing the paper). I am just wary of readers getting the erroneous impression that there is consensus about the position of Gerobatrachus. Others do not accept it either (I have had discussions about this with other paleoherpetologists) although they may not have expressed it in print, contrary to me.

By the way, I also sent you and e-mail message. I hope that it went to an account that you consult once in a while. Thanks again for your precious help. Michel Laurin (talk) 22:33, 9 December 2012 (UTC)

Thank you for pointing out the discussion; I have added a comment. It looks as though User:Stranger forever will be doing the necessary updates.

Wikipedia does resolve Unicode; Marjanović can be coded as Marjanović in the edit box.

I check my email regularly and will be responding. Peter Brown (talk) 23:50, 9 December 2012 (UTC)