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WikiProject Animals (Rated Start-class, Top-importance)
WikiProject icon Bilateria is within the scope of WikiProject Animals, an attempt to better organize information in articles related to animals and zoology. For more information, visit the project page.
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WikiProject Animal anatomy (Rated Start-class, High-importance)
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differences in classification of superphyla[edit]

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. -- (talk) 22:39, 21 April 2012 (UTC)


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)

Nielsen phylogeny[edit]

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 (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)[edit]

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[edit]

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[edit]

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)