Talk:Lissamphibia

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I suggest this page belongs in page "Amphibia"/"Amphibian". Please see the Talk:Anura page where I hope we can coordinate all things Amphibian. Stanskis 02:37, 17 July 2005 (UTC)

Lissamphibia is a specific subclass of Amphibia. So unless you adopt a cladistic crown group definition of a monophyletic Lissamphibia, (in which case "Lissamphibia" = "Amphibia" and all other prehistoric amphibians are cladistically defined either as "tetrapods" or "four-legged animals") the two are not synonymous.
so, in short:
  • it is not agreed that Lissamphibia are monophyletic
  • the stem group interpretation is just as valid as the crown group interpretation, if we use this than Amphibia is not the same as Lissamphia even assuming the latter is a monophyletic taxon
  • while the cladistic explanation is being widely (and increasingly) adopted there are still those who prefer the Linnean taxonomy
for all these reasons, Lissamphibia should not be merged with Amphibia M Alan Kazlev 04:23, 18 July 2005 (UTC)

Dating[edit]

"The publication of a Permian-period stem form Gerobatrachus hottoni showed the frogs and salamanders had a common ancestor more recently (ca 290 Mya) than had been thought by using the molecular clock alone."

This is not obviously correct. The existence of a stem group taxon does not place a lower bound on the age of a crown group, as stem group lineages do not automatically go extinct on the appearance of the crown group. For example, monkeys could be considered a stem group with respect to the ape crown group (or vice versa), but neither is yet extinct. (The cited National Geographic Article at Gerobatrachus hottoni is in disagreement with the above statement.)

You are absolutely correct. Even if Gerobatrachus hottoni were a stem-batrachian, that would say nothing about the geological age of Batrachia. Furthermore, these affinities have been disputed (Marjanović & Laurin 2009). I find that this page could use a lot more references. For instance, no citation is provided to any paper supporting a monophyletic origin within lepospondyls (although several were published). Similarly, there are far more molecular studies, but Sigurdsen and Green (2011), cited as such, is a morphological study, not a molecular one. I could fix all these problems; should I? Stranger forever (talk) 14:54, 8 December 2012 (UTC)
Anderson et al. (2008) says, not just that Gerobatrachus hottoni is a stem batrachian, but that it is "the immediate sister taxon to Batrachia". Doesn't that mean that Batrachia is about as old as Gerobatrachus? If so, the article isn't that far off the mark. Peter Brown (talk) 23:43, 9 December 2012 (UTC)
Hi Peter, even if Gerobatrachus hottoni were the immediate sister-group of Batrachia (which I doubt), that would imply nothing about the age of Batrachia, except that its stem is at least as old as Gerobatrachus hottoni. But that fixes no maximal age. So the text in the introduction is wrong. Gerobatrachus hottoni does not falsify any molecular dating of Lissamphibia or of Batrachia. Michel Laurin (talk) 07:48, 10 December 2012 (UTC)
Michel, you have added that, if Anderson et al. are correct about Gerobatrachus hottoni, then it is the oldest known lissamphibian. It is really unclear why a stem-batrachian needs to be a lissamphibian at all, especially if the subclass is polyphyletic. The real problem, which also underlies my question in the next section, is that the article provides no clear delimitation of Lissamphibia. This is not something I know and surely the general reader will fare no better. Peter Brown (talk) 18:04, 11 December 2012 (UTC)

References

  • Marjanović, D.; Laurin, M. (2009). "The origin(s) of modern amphibians: a commentary". Evolutionary Biology. 36 (3): 336–338. doi:10.1007/s11692-009-9065-8.  Unknown parameter |author-separator= ignored (help)

Doubts about monophyly[edit]

According to the Lissamphibia#Relationships and definition section,

Not all paleontologists are convinced that the lissamphibia are indeed a natural group, as the various characteristics are also shared with some Palaeozoic amphibians. . . .

Is there some reason to suppose that these Palaeozoic amphibians aren't lissamphibians? If so, what is it? If not, this clause doesn't make sense. Peter Brown (talk) 00:36, 11 December 2012 (UTC)

Mmm. The whole article is a muddle. There shouldn't be controversy (and refs) in the lead section; the lead should only summarize the rest of the article, not introduce new stuff; the article should plainly state alternate points of view, and cite them; it should actually describe the group, not suggest characters that possibly describe some of them. WP:TNT does spring to mind. Chiswick Chap (talk) 09:19, 12 March 2013 (UTC)