Talk:Bilateria

differences in classification of superphyla
The taxobox in Animalia and the article lists the Ecdysozoa, Lophotrochozoa, and Platyzoa as separate superphyla at the same level as Deuterostomia  The article and taxobox for Bilateria, to which all these groups belong, recognizes the first three of them as members of Protostomia, correlate to  Deuterostomia, as does the classification in the talk for Animalia. There is also an article for Protostome; it & its taxobox similiarly group the three, as do the articles for Ecdysoza, Lophotrochozoa, and Platyzoa, all supported by both embryological and molecular data.

If these two scheme are in fact competitive analyses, surely the 2 hypotheses should at least be mentioned in all the relevant articles, instead of some silently adopting one and some the other. (I was taught protostomia, but that doesn't prove it correct) DGG 03:30, 4 November 2006 (UTC)


 * The classification of Ecdysozoa, Lophotrochozoa and Platyzoa as equal to Deuterostomia is relatively recent, and likely not fully accepted. Yes, the two schemes should be mentioned in the various articles, but we don't need a detailed discussion in every article; perhaps Protostome is the best place for that. -- Donald Albury 01:15, 5 November 2006 (UTC)


 * Is there a recent paper supporting the monophyly of the platyzoans? I've been trying to appraise myself of the most current science for the Lophotrochozoa article, and the most recent and methodologically rigorous study I've found (Paps et al. 2009) indicates that Platyzoa should be considered a paraphyletic group allied with Lophotrochozoa, with Platyhelminthes as a close sister to the "Spiralia", and the other proposed members as outgroups more closely related to Lophotrochozoa than Ecdysozoa. --24.5.147.203 (talk) 22:39, 21 April 2012 (UTC)

Cambrian
I don't know much about this at all, but this reference suggests these distinctions date back to the Cambrian era. There probably should be a paragraph concerning (postulated) evolutionary origins. MaxEnt 16:32, 29 June 2007 (UTC)
 * http://cas.bellarmine.edu/tietjen/Ecology/early_animal_evolution.htm

Telecine Guy (talk) 23:59, 8 June 2018 (UTC)
 * Update:
 * New find moves Bilateria into The Ediacaran Period, between 635 and 541 million years ago, Pre-Cambrian era.
 * Ref Digital Technology and Science Editor, The Sun,6th June 2018:

Nielsen phylogeny
I'm no expert in the phylogeny of animal phyla, but is the phylogeny given (cited to Nielsen) at all credible? It looks like a rather old, and now obsolete, version to me (particularly in presenting the Bryozoa and Entoprocta as forming a single clade which I believe was discarded quite some time ago, and uniting the annelida and arthropoda which was conventional wisdom until the late 20th century or so but which I'm not sure is widely held any more). Kingdon 14:32, 24 August 2007 (UTC)


 * Seems like no older than 2001, but it's troublesome by the fact that Nielsen proposed an alternative phylogeny about 2 years later, in order to solve the discrepancies between morphological data and molecular dito. Therefore Nielsen's phylogeny of 2001 should be considered obsolete. Said: Rursus ☻ 17:21, 4 November 2007 (UTC)


 * Newer articles based on molecular methods tend to agree in dividing the Bilateria into the three supergroups Lophotrocozoa, Ecdysozoa and Deuterostoma. The arthropods (or Panarthropoda) should definitely not be close to either the Annelida or the molluscs. Seven years is a very long time in phylogeny these days, and the tree should definitely be exchanged for a newer one. Jonht (talk) 16:38, 8 March 2008 (UTC)

The Nielsen phylogeny is really old. It should be removed or replaced. The german "Bilateria" page is quite up to date. —Preceding unsigned comment added by 78.48.240.154 (talk) 12:34, 15 November 2008 (UTC)

I'm also quite amazed at the inclusion of the Brachiopods and Phoronids into the Deuterostome clade, I was never aware this was even considered. I think this cladogram needs to be seriously updated or scrapped. Rolf Schmidt (talk) 04:59, 9 July 2010 (UTC)

Echinoderms (Taxobox)
20,000 species are quoted, whereas the Echinoderm page only says 7,000 species - which is correct? --Graminophile 11:08, 22 October 2007 (UTC)

Nouns and adjectives
Are nouns and adjectives confused in our articles? Or am I confused (just as likely)?

Bilateria is a noun, plural. What is its singular?

Bilateral is an adjective.

Bilaterian is an adjective; Encarta lists it only as an adjective. Examples from Google's first page: bilaterian fossils, bilaterian features, bilaterian animals, bilaterian ancestors, bilaterian evolution, the Bilaterian superphylum -- but also just one use as noun: "the early origin of bilaterians".

Can bilaterian also be a noun? It looks like it here: "The urbilaterian (< German ur- 'original') is the hypothetical last common ancestor of the bilaterian clade, i.e., all animals having a bilateral symmetry.", but seems wrong (to me) elsewhere.

Thanks. - Hordaland (talk) 19:52, 27 September 2009 (UTC)


 * "Bilateria" is tricky. No formal singular. Possibly a collective noun. Can denote both the actual critters (plural) and the taxon (abstract singular noun?) Are you sorry you asked? :-)
 * Adjective functioning as noun (in this case "bilaterian") is normal - there's an implied noun, e.g. "bilaterian animal".  Other include e.g. "the Americans". Hope this helps. --Philcha (talk) 07:06, 28 September 2009 (UTC)


 * I am an American and apparently also a bilaterian. Not sorry I asked. :-)  - Hordaland (talk) 09:28, 28 September 2009 (UTC)

Updated Phylogeny
Given there has been discussion for 7 years now that the phylogenetic tree on the page is inaccurate by modern standards, I've replaces the Nielsen phylogeny with a modern tree which claims to have "broad consensus", from a 2011 review article in "Organisms Diversity and Evolution". This article discusses many alternative trees as well.

I am not a biologist and do not really know much about ancient phylogenies -- that's what I came here to learn! Nielsen's phylogeny was inconsistent with info from most other wiki pages, which confused me. This is just to say that it would be good if someone more knowledgeable could double check that my addition is OK.

I also have only made minor modifications to the text preceding the new tree, it might need more updates. This tree might be useful to copy/expand to other pages too (eg the metazoan page), but I have not looked into that yet. Ahalda (talk) 17:53, 11 August 2014 (UTC)


 * The tree as shown in the article is totally messed up now. It depicts Deuterostomes as a non-existent clade, even though this is not yet the scientific consensus. The remainder of the section contradicts the depicted tree. The Edgecombe et al. article from Organisms Diversity & Evolution does not agree with the tree presented in this section: Figure 1 of that paper (available at: )shows Deuterostomes consisting of Ambulacraria and Chordata. On the other hand, in this section, Chordata is shown as a sister group to Protostomia, with Xenambulacraria as an outgroup. It is important to remember that Xenambulacraria is a proposed clade, and there is not yet consensus as to its existence. As such, the tree now totally contradicts the article that Ahalda based the tree on, as above.
 * The citations given as support of proposed Deuterostome obsolescence do not support the tree currently presented. The Yamasaki et al. paper admits: "Although the majority of our analyses recover a monophyletic group of chordates plus protostomes, the support values are very low, meaning there is no solid evidence to refute the traditional protostome and deuterostome dichotomy" [emphasis mine].
 * Where is the consensus for the demolition of Deuterostomes? Where is the consensus that Chordata are a sister group to Protostomia, with Ambulacraria far away as an outgroup? I see no consensus. The sources do not support this idea.
 * Therefore, somebody please fix this broken tree. It does not reflect the current consensus, and it contradicts the section itself. BirdValiant (talk) 04:28, 24 August 2019 (UTC)
 * I decided to resurrect the long-term-consensus tree from June 2019 and place it above the newly proposed one with Xenambulacraria. This hopefully will show readers the usual consensus of protostomes vis-à-vis deuterostomes, and also allow the reader to see the new proposed one. I included the authors' caution that their one paper is not enough to overturn the usual deuterostome-protostome dichotomy. BirdValiant (talk) 05:00, 24 August 2019 (UTC)
 * I strongly support this change. I'd been meaning to do something similar, a tree based on the Giribet/Nielsen consensus phylogenies, but never got around to it. An article as central as bilateria has to use a consensus scheme, built on multiple secondary sources, not the latest controversial proposal in a couple of primary sources. I'd also be inclined to trim the tree of the extinct groups whose placement is speculative. This tree should show the mainstream thinking on the relationships of the main groups at a glance.  Jts1882 &#124; talk 06:23, 24 August 2019 (UTC)


 * That's fine. It's hard to accomodate Xenacoelomorpha - Ambulacraria sistership without "messing everything up". Xenacoelomorpha - Ambulacraria sistership was the main result of this paper.Jmv2009 (talk) 19:08, 1 September 2019 (UTC)
 * The consensus remains that Deuterostomes are a clade and that xenambulacraria (comprising xenacoelomorpha and amulacraria) are the sister clade to the chordates. See and https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7978419/ for example, though these conclusions are not beyond doubt by any means. I agree that the trees in this page need updating [[User:Anropa|Anropa] (talk) 14:53, 31 December 2023 (UTC)

modified infobox
It appears that last year the indentations of the taxa in the infobox were modified which inadvertently moved the nematode worms and the arthropods out of ecdysozoa. I have partially reverted this. But if the modification was intentional, then please feel free to restore the page to how it was before I edited it. Bwrs (talk) 10:48, 26 July 2017 (UTC)

lede wording
"The bilateria, bilaterians, or triploblasts, are animals with bilateral symmetry, "

I'd like to discuss this. Although all members of Bilateria have bilateral symmetry, I'm not sure it has been established that all animals with bilateral symmetry are Bilateria. Does anyone have a ref on this?Ordinary Person (talk) 09:50, 14 September 2019 (UTC)

Of course you appear to be right. Jmv2009 (talk) 13:30, 19 November 2019 (UTC)

Merge Nephrozoa into Bilateria
Per the above discussion, it's clear that the Xenacoelomorpha-Nephrozoa sister relationship is supported by most genomic evidence. What most of this article discusses are Nephrozoans, so there's very little point having another article that mostly overlaps in scope with this one. This article needs to talk more about the morphology of Xenocoelomorphs and the difference between them and Nephrozoans. it is also possible that the Urbilaterian article could also be merged into this one. Hemiauchenia (talk) 01:20, 14 January 2020 (UTC)


 * I'm against such a proposal. I think that it's important to have a separate article for major clades, even if these articles amount to stubs. This is very common throughout the tree of life that we have here. Merging and leaving a redirect would make the situation far less clear for the reader. BirdValiant (talk) 06:05, 14 January 2020 (UTC)
 * Agree. The major clades should have their own articles, even if limited in scope. We don't want a lot of duplication, so it makes sense that most of the detail is handled by one of the articles, in this case the better known and more stable one.    Jts1882 &#124; talk 08:28, 14 January 2020 (UTC)


 * Oppose merge - The clades are not synonymous. Merging them would make it even harder for readers to parse the distinctions. --Nessie (📥) 15:21, 14 January 2020 (UTC)
 * The comments of this imply that the current bilateria article is somehow clear in it's distinction to Nephrozoa, which just isn't true. Regardless of what one thinks about merging, the current article on bilaterians is laughably bad and completely inadequate, (probably only worth a start class rather than a c class) considering it gets 100k views every year and is such an important clade. No mention of the anatomy of Xenacoelomorpha is present, and the article treats bilateria as if it is solely regarding Nephrozoans. I'm not massively fussed on the merger, but the bilaterian article needs to be significantly improved. I've also seen that none of the comments have any opinion on the merging of the Urbilaterian article into bilateria, and I would like to hear some feedback on that idea. Hemiauchenia (talk) 04:18, 15 January 2020 (UTC)
 * I oppose that merger too, at least for now. I think the effort should be to improve the articles rather than just rearrange the material. Perhaps in doing so the case for mergers or not might become clearer.
 * I think the problem with this article is that it was mostly written ten years ago and only a few bits have been updated, without consideration of the overall structure. It looks like parts were written when aceols were considered secondarily simplified (a view that is making a comeback with some scientists.) and the primary division was protostome/deterostome. The phylogeny was updated to show Nephrozoa but other sections were not changed to reflect this. The description of the phylogeny says it's a 2011 consensus, although the actual cladogram has been updated without proper sourcing (a general problem across the higher animal taxa articles). It's difficult to know where to start.  Jts1882 &#124; talk 08:59, 15 January 2020 (UTC)


 * Oppose Some general points. 1) There appears to be a significant branching there. 2) The features of both branches, and the root can be discussed for such a branching. 3) At this point it may not be clear what the salient features of Bilateria vs Nephrozoa exactly are, given that the exact phylogeny is balancing between "determined by molecular analyses", and "still under debate." — Preceding unsigned comment added by Jmv2009 (talk • contribs) 14:39, 18 February 2020 (UTC)
 * Question Should this proposal be closed? It's been more than a month. Or, do we need a Request for Closure? BirdValiant (talk) 19:33, 23 February 2020 (UTC)
 * Apparently the controversy is still on as of 2019, thought this obviously isn't news to other commenters. Though the authors of this study are far from certain and this is still unresolved. I agree that discussion should be closed, but there should be some kind of plan to comprehensively improve the article, an article as important as Bilateria should at least have GA status really. Hemiauchenia (talk) 19:58, 25 February 2020 (UTC)


 * Oppose. It's clearly notable and a major clade. Need for updating does not mean need for merging. Chiswick Chap (talk) 21:45, 24 March 2020 (UTC)

Actually, if Xenambulacraria is monophyletic, either Deuterostomia becomes synonymous with Chordata, or Nephrozoa becomes synonymous with Bilateria. Jmv2009 (talk) 12:10, 27 June 2020 (UTC)


 * Not for us to speculate, really. If it emerges that one of those is the new taxonomy as recognised in major phylogenetic review papers, we will have to go with it. That change may be in progress but is not yet complete. The proposal should be closed, editors are not in favour of such a premature reorganisation. Chiswick Chap (talk) 12:28, 27 June 2020 (UTC)
 * In the Philippe et al. 2019 paper, the authors literally say
 * From WP:PRIMARY, "Any interpretation of primary source material requires a reliable secondary source for that interpretation." This means we cannot start doing speculation and advocating which way the field will go. The dust has not settled. If the field comes to an agreement that Bilateria should be merged with Nephrozoa, or that Deuterostomia should be obsoleted (as you similarly advocate), then and only then should Wikipedia follow. BirdValiant (talk) 15:20, 27 June 2020 (UTC)
 * From WP:PRIMARY, "Any interpretation of primary source material requires a reliable secondary source for that interpretation." This means we cannot start doing speculation and advocating which way the field will go. The dust has not settled. If the field comes to an agreement that Bilateria should be merged with Nephrozoa, or that Deuterostomia should be obsoleted (as you similarly advocate), then and only then should Wikipedia follow. BirdValiant (talk) 15:20, 27 June 2020 (UTC)

Two possible trees
Is another possible alternative xenambulacraria being nested within a natural deuterostome group? 74.101.251.49 (talk) 06:05, 15 August 2022 (UTC)

Centroneuralia
Several recent studies refer to the Chordata+Protostomia group as "Centroneuralia", removing confusion with "Nephrozoa" which implies a Deuterostomia+Protostomia grouping. Should this be followed in the alternate tree shown in the article grouping Chordata and Protostomia? Here, this grouping is referred to as Nephrozoa, which clashes with the common use of that term. Chaotic Enby (talk) 13:32, 28 January 2023 (UTC)


 * I agree it is important not only to mention it in text but also present an alternative phylogram. Btw, the high level of detail of the phylograms and taxobox is counterproductiv - the higher-level clades inside Spiralia also are far from certain. Petr Karel (talk) 15:24, 26 January 2024 (UTC)