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I have moved the information in Eutheria back to this page. Some time ago, a user posted a question on the talk page for Marsupial, wondering if the subclass should be changed to Metatheria. Since neither I nor the User (PlatinumX) was qualified to make such a decision, I decided to solicit users for their input. Unfortunately, after four opinions were voiced, no one else took any notice. At the request of UtherSRG, I decided to go ahead with the changes recommended following my input solicitation. The results were as follows: three of the four votes for a system dividing the class Mammalia into three subclasses, Monotremata-Marsupialia-Placentalia. Josh argued that this system should be adopted for clarity, because derivatives of the three taxa are the names used in everyday speech (when was the last time you heard a marsupial called a metathere?). The only other system that received a vote (one vote from me), was a system in which there are two subclasses (Prototheria, consisting of Monotremata, and Theria, consisting of Marsupialia and Placentalia). The vote for this was cast on the grounds of evolutionary taxonomy, in which the groups most closely related are grouped most closely. To paraphrase Josh again, this provides very little evolutionary information, but the cost is that one must list both subclass and infraclass in every taxobox. Suffice it to say, this is the purpose I have in moving it back to Placentalia.--Ingoolemo 17:31, 2004 Jun 17 (UTC)


Where does Meridiungulata fit into all of this? Descriptions on various other pages (such as Atlantogenata) seem to indicate it's a sister-clade of Xenarthra and Afrotheria, both of which are listed here, but there's no mention of Meridiugulata on this page. -- Foogod 23:39, 29 December 2005 (UTC)

Why a zorse?[edit]

Placentalia is a huge class containing many common and/or interesting mammals. Out of all these, a zorse is chosen for the illustration? —Michael Shields 23:43, 22 January 2006 (UTC)

It's a very huge infraclass, yes, but there is no real reason not to use a "zorse" or so. A species might however be better than a hybrid. Ucucha (talk) 14:28, 1 March 2006 (UTC)


I've been searching in taxonomic databases and nowhere there's the differentiation about "placentalia" and "eutheria". My conclusion is that this differentiation is false and the two taxons are the same. The two articles must be fused. Llull 14:22, 1 March 2006 (UTC)

See [1] for an example of a database which does not join them. Ucucha (talk) 14:24, 1 March 2006 (UTC)
This classification is an unfruitful proposal. See all the other pages of the same project where there isn't differentiation between the two taxons. This lack of differentiation is in other reputed databases (link) where there's the "synonym" label. Llull 14:43, 1 March 2006 (UTC)
Note that it was based on McKenna & Bell's 1997 influential classification of mammals. I think it's better to use authoritative original sources than such databases, which often have incorrect or incomplete taxonomy. Ucucha (talk) 14:47, 1 March 2006 (UTC)
Sorry, but I think that this can't be said about NCBI that contains the major database of rRNA. In the link you put there is the taxon "Edentata" that is a group misestimated since the molecular analysis. This proposal of classification isn't used today. Llull 15:08, 1 March 2006 (UTC)
Yes, but that does not mean its taxonomy is correct. There are many paleontologists who still use McKenna & Bell's scheme. "Molecular" is not the same as "correct". (see the guinea pigs-aren't-rodents affair) Ucucha (talk) 15:40, 1 March 2006 (UTC)

Merging may indeed be a good idea (still). The two terms are, if not completely, practically synonymous. The slight difference in some classifications (Eomaia, Bothriolestes and the others) could be explained in the text, while most information in both articles should be the same. Ucucha (talk) 15:03, 1 March 2006 (UTC)

I think that the two articles should be marged and that in "Eutheria" article could be a note about this proposal of classification that differenciate "placentalia" when everywhere is the same. Llull 15:10, 1 March 2006 (UTC)
Or in Placentalia... depends on which name is most common. A quick Google search gives a large majority for Eutheria. Maybe the article should be "placental", the most commonly-used English name. Ucucha (talk) 15:38, 1 March 2006 (UTC)
Well, this is not really very important for me. Taxonomically today the preferred form is "eutheria" (and I think that this form should be used in the table), but the encyclopedias use to prefer the vulgar names for the articles names (dog in the article name and Canis lupus familiaris in the table, for example). Llull 15:43, 1 March 2006 (UTC)
Over the last several decades, they've discovered several important non-placental Eutherian mammals such as Eomaia. Eutheria dates back to about 160 mya while Placentalia is thought to date from about 90 mya. Zyxwv99 (talk) 23:25, 7 August 2015 (UTC)


At the risk of appearing ignorant: Aren't ERVWE1-like proteins particularly relevant to the evolution of placentals? In any case, perhaps the virus thing deserves a mention?—Arpose (talk) 09:48, 17 February 2016 (UTC)

Maybe a date change?[edit]

On the Laurasiatheria page, it says that it was from 99 Ma to present. But this page says it's from 66 Ma, so which is wrong? Placentalia or Laurasiatheria? Caehlla (talk) 11:20, 20 November 2017 (UTC) Caehlla (talk) 11:20, 20 November 2017 (UTC)

I believe that they're using different methods to arrive at the answer, so, technically, neither is wrong in context. Having said which, we should be consistent where possible, and this page gives a source for its figure, while Laurasiatheria does not, so I'd suggest that that's the one to change. Ideally, though, we should explain it better, and that would require sources I don't have with me right now. Anaxial (talk) 18:00, 21 November 2017 (UTC)
Not to mention that Epitheria has a "Late Cretaceous-Recent" temporal range. So, which of the three is correct? I hope you can give an answer. Thank you Caehlla (talk) 23:00, 29 November 2017 (UTC)