Talk:Reptiliomorpha

Homo sapiens

"More recently Reptiliomorpha has been adopted as the term for the largest clade that includes Homo sapiens but not Ascaphus truei ( a primitive frog)" That sounds like nonsense to me. Homo sapiens (Human) is not a reptiliomorph (obviously). Giant Blue Anteater 07:42, 4 July 2006 (UTC)

Cladistically speaking H. sapiens is. Read up the page on cladistics for more. This is a very different way of classifying and understanding organisms to the old Linnaean taxonomy M Alan Kazlev 21:02, 4 July 2006 (UTC)

Oh I get it. Just because an animal evolved from a non-amniotic reptiliomorph dosen't mean it's not a reptiliomorph anymore. Giant Blue Anteater 23:55, 20 September 2006 (UTC)

Cotylosauria?

Some other articles say that Cotylosauria is no longer recognized (although a lot still use it as an ordo) - maybe it has become time to update the taxonomy? Shinobu (talk) 00:05, 29 December 2008 (UTC)

Scientific classification wrong?

This article puts Reptiliomorpha as a superorder within the class Amphibia. The Tree Of Life webpage, however, has both Reptiliomorpha and Amphibia as distinct classes within the superclass Tetrapoda: http://tolweb.org/Terrestrial_Vertebrates/14952 —Preceding unsigned comment added by 88.109.20.148 (talk) 09:33, 28 September 2010 (UTC)

Not wrong, just two different systems. The ToL page does not recognize any ranks such as class or superclass. They're also using different definitions of the word Amphibia. Ours is apparently sensu lato (in a paraphyletic sense, all non-reptilian tetrapods are "amphibians"), theirs is sensu stricto (Amphibia as a monophyletic clade including only frogs, salamanders, and their extinct relatives). MMartyniuk (talk) 00:45, 29 September 2010 (UTC)

Sesu lato means "in the wider sense", to indicate we are not dealing with any of the modern groups. The TOL-page on these critters is written by Michel Laurin, who also happen to be the chair of the 2004 PhyloCode committee, thus the strict non-Linnaean approach. Laurin is a proponent of the crown group concept, where all systematic units should be nose based, anchored in living species. Thus his amphibia is equal to Lissamphibia. Petter Bøckman (talk) 09:06, 13 February 2011 (UTC)

Cladogram

Thank you Smokeybjb for the cladogram, they are a bugbear to make! One thing though, most of it detail the phylogeny of the lepospondyls. Would it be an idea to collapse the lepospondyl section a bit? Petter Bøckman (talk) 19:43, 3 March 2012 (UTC)

Sure, I put this same cladogram in the lepospondyl article, but seeing as this is an article on reptiliomorphs, all the different leposnondyls aren't really necessary here and we could just condense Lepospondyli into a single branch. Smokeybjb (talk) 22:54, 3 March 2012 (UTC)

Just want to say thanks for the cladogram once again, it's really nice work (I hate to make those). It's nice to have Westlothiania showing, it's one of those fully groups showing up in strange places in all phylogenetic works. Petter Bøckman (talk) 07:24, 4 March 2012 (UTC)

Some of us find cladogram construction fun. Chacun à son goût. All the same, if a cladogram is included in an article, the title of the article should normally appear as a label. Peter Brown (talk) 01:08, 18 August 2013 (UTC)

So what is a reptiliomorph?

The article does not answer the question. The lead gives two characterizations:

• For the cladist, it is a clade more inclusive than Amniota. There are lots of such clades, however, all the way up to crown Eukaryota.
• Traditionally, in the wording prior to my (perhaps clumsy) edit of 9 August, it is the more amphibian line ancestral to the amniotes. My edit dropped the word "more" since no scale is apparent to make clear what it is to be more or less amphibian. The lead of the Amphibian article makes clear that amphibians are tetrapods; in the traditional sense, therefore, Reptiliomorpha is some group more inclusive than the amniotes but not more inclusive than the tetrapods.

On either of the characterizations in the lead, Reptiliomorpha might be synonymous with Tetrapoda.

The Characteristics section gives attributes of basal reptiliomorphs. We are told that these animals are "land-based". The caption for the Archeria image says that the genus was aquatic, so apparently it was not basal?

In the Changing definitions section, it is unclear how much divergence is merely nomenclatural and how much reflects conflicting phylogenies. I gather that von Huene's definition was merely a nomenclatural variant?

What is the point of the cladogram, which does not even include Reptiliomorpha as a label? The single species Westlothiana lizziae is represented as the sister of Lepospondyli; assuming that Benton agrees that Reptiliomorpha includes Amniota, he must disagree with this cladogram, since he takes Reptiliomorpha as the sister of Lepospondyli. In more detail, how does his view differ? If Benton's is a fringe view, it should not even be mentioned.

Perhaps further study of the article would yield clarity. Too much, however, is being asked of the general reader. Peter Brown (talk) 18:20, 17 August 2013 (UTC)

If Reptiliomorpha has been defined as a clade, there must be a definition. Anybody with access to recent literature on this clade should be able to track it down. If it has been used as a Linnean taxon, it must have a diagnosis that can be cited (i.e. "reptiliomorphs are amphibians/stem amniotes with these characteristics). Shouldn't be as confusing as it currently is! MMartyniuk (talk) 20:20, 17 August 2013 (UTC)

It seems that there are several conflicting definitions and diagnoses. Unless "Reptiliomorpha" is straightforwardly ambiguous, there must be a core concept which these formulations attempt to capture. For starters, we need a characterization of this concept, as theory-neutral as possible. Then we need to be shown how different theories lead to different formulations. Peter Brown (talk) 21:09, 17 August 2013 (UTC)

Reptiliomorpha has, indeed, been defined as clade: Laurin (2001, p. 208) defined it as "the largest clade that includes Homo sapiens but not Ascaphus truei". This definition was later repeated in a 2004 JVP article by Vallin and Laurin (p. 58). As mentioned in the article, what taxa other than amniotes and diadectomorphs belong to such defined Reptiliomorpha depends on the phylogenetic position of Lissamphibia (or at least Anura) within Tetrapoda. Major published phylogenetic studies (cited in the article) recovered lepospondyls as more closely related to amniotes than seymouriamorphs and embolomeres were (that includes Ruta et al. 2003, contrary to what Benton seems to be implying on p. 99 of the 3rd edition of Vertebrate Palaeontology); depending on whether lissamphibians are or are not nested within Lepospondyli, the aforementioned groups may or may not be reptiliomorphs. (Plus, embolomeres were occasionally suggested to lie outside the least inclusive clade containing amniotes, lepospondyls and temnospondyls; if confirmed, then, not matter whether lissamphibians are nested within lepospondyls or temnospondyls, embolomeres would be outside Reptiliomorpha. --Macrochelys (talk) 21:26, 17 August 2013 (UTC)

I and MMartyniuk agree that the article is too confusing as it stands. Is your note intended to provide guidelines for rendering it more comprehensible? If so, please make your suggestions clearer. I can't see that you have even attempted to address my complaints.

The section Early reptiliomorphs explicitly includes Seymouriamorpha. If this is controversial, it should be so noted.

Perhaps we need three subsections indicating how Laurin's definition plays out under the three theories (lepospondyl, temnospondyl, and polyphyletic) of lissamphibian phylogeny.

In any case, your entire discussion presupposes Laurin's Phylocode-compatible definition. The lead currently suggests, however, that there is another. Since the term goes back to 1934—pre-Hennig—this seems likely, and requires treatment.

Peter Brown (talk) 22:51, 17 August 2013 (UTC)

I think his post is suggesting there is a rough consensus as to a phylogeneitc definition we should follow in the article. Reptiliomorpha = what PhyloCode would call Pan-Amniota, but this is problematic because it is defined with respect to Lissamphibia, the phylogeneitc position of which is not clear. A concept/definition/diagnosis from the 1930s would also exist, but current common use needs to be demonstrated if we're going to include references to eighty-year-old science. Surely the non-phylogeneitc concept has been modified since then. MMartyniuk (talk) 22:57, 17 August 2013 (UTC)

Addressing your complaints, then: as far as I know Reptiliomorpha is currently used as the name for the clade containing amniotes and everything more closely related to them than to anurans; I'm not aware of any phylogenetic definitions of the clade other than Laurin's. The informal "reptiliomorph" is occasionally used for stem-amniotes alone (e.g Coates et al, 2008), but the name seems to be rarely used with this meaning. I'm not aware of the name having any other meaning in recent publications, certainly I have not heard of it having the same content as Tetrapoda.
Unfortunately, no matter which one of these two meanings one picks, it remains uncertain which groups of tetrapods belonged to Reptiliomorpha, and this needs to be noted in the article as well. The inclusion of, for example, seymouriamorphs is controversial, as they may lie outside the least inclusive clade containing amniotes and lissamphibians, which would of course mean they were not stem-amniotes. E.g Vallin and Laurin (2004) explicitly exclude seymoriamorphs from their Reptiliomorpha.--Macrochelys (talk) 23:38, 17 August 2013 (UTC)

The reason it is confusing is because they have no defining characteristics that separate them from reptiles. They are just assumed/supposed to be some kind of proto-reptile. 70.16.207.189 (talk) 23:22, 13 January 2014 (UTC)

The tern Reptiliomorhpa, or rather the vernacular form reptiliomorph is an old term with several meanings. As a grade, they are assumed to be proto-reptiles as IP above says, cut of down the tree by it's separation from the Temnospondyl stock, and snipping off the reptiles at the development of amniotic eggs (somewhere between Diadectomorpha and Hylonomus). The problem with the phylogenetic definition is that as long as the origin of Lissamphibia is unknown, the actual content of Reptiomorpha is unstable, and hence the unit serve no real purpose other than as a name on a list. The sections on characteristics and evolutionary history are based on the older paraphyletic understanding of the group, which covers some very crucial moments in the evolutionary story of land vertebrates. Petter Bøckman (talk) 11:40, 14 January 2014 (UTC)

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defined as largest clade etc

A simple statement like this should be easy to source. Was it 2001 or 2004? --Richardson mcphillips (talk) 22:54, 8 May 2017 (UTC)

Both. And there are inline citations to both sources. --Jules (Mrjulesd) 17:34, 9 May 2017 (UTC)