Talk:Eutheria

message: 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)
:Since nothing happened in the last three years, I decided to use the system that is most commonly used among systematic biologists. That means that Mammalia is split in three: Prototheria (which is known to be polyphyletic, but only includes Monotremata in this context), Metatheria (which is inclusive of, but not the same as, Marsupialia) and Eutheria (which is inclusive of, but not the same as, Placentialia). DaMatriX 21:40, 26 April 2007 (UTC)
replies: text:  Rather than do a reboot of these various old comments (I'm not quite couragous enough for that), I would like to point out that various sources, such as Benton's Vertebrate Paleontology (2005) the Tree of Life, and the phylogeny archive are all consistent with the phylogenetic grouping of Theria to the exclusion of Prototheria (of which Monotremata is the only known-for-sure member).  Theria is united by synapomorphies including live birth, chochlear coiling, and others.  There is little current debate, and the arguments over this on this talk page are not even up-to-date.  With regards to the eutheria node in particular, the node is currently synonymous with placentalia, but includes extinct outgroups to placentalia, which should be emphasized and more heavily discussed in the article.  Metatheria is in even greater need of this discussion, as the taxobox doesn't even list extinct metatherians.  While Dysmorodrepanis is right in that phylogenetic systematics will underrepresent polytomies, the most parsimonious trees will have features being evolved the fewest number of times, thus providing the bifurcating trees we currently use.  Until much finer resolution and much better records can be established (things that aren't easy even with extant species), it is wise to accept the current most parsimonious tree with the knowledge that further data can occassionaly shift relationships.  Hedging one's bets for possible future information is rather pointless! Tigerhawkvok (talk) 05:55, 25 July 2008 (UTC)
thread_title:  Subgroups of Mammalia 

message: I've been searching in taxonomic databases and nowhere there's the differentiation between "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)
thread_title: Fusion

message: The edentata griup has been added when the genetic analisys have demostraed that is a poliphylenic group. Then it must be deleted. Llull 09:41, 11 March 2006 (UTC)
thread_title: Edentata

message: Although the membership of Eutheria and Placentalia are very similar, there is a difference between how the two names are used by many paleontologists.  Placentalia is a crown group embracing all extant placentals.  Eutheria is a total group (or "panstem") that includes all creatures more closely related to placentals than to their next closest living kin (presumably marsupials).
The difference in membership is small because few fossil species are known from the stem group (that is, belong to Eutheria but not Placentalia).  So it may not be worth it to separate the two articles.  On the other hand, future discoveries may uncover many eutherians that aren't placentals, providing much food for a separate article about Eutheria.  In either case, it would be good to explain the distinction in this article.
Cephal-odd 04:18, 27 October 2006 (UTC)
thread_title:  difference between Eutheria and Placentalia 

message: Terminology, facts and new hypotheses are really challenging mdoern classification of mammals.
"Eutherians are distinguished from other mammals in that the fetus is nourished during gestation via a placenta while, in general, this is not the case with other mammals (Bandicoots are a conspicuous exception to this rule.)"
-- Almost all marsupials have some form of placenta that is essential for gestation.
Also the realtionship between Metatheria, Prototheria and Eutheria is under scrutiny as conflicting reports suggest that Meta- and Proto- may be sister clades to the exclusion of eutheria.
--ZayZayEM 02:05, 26 April 2007 (UTC)
replies: text: To my knowledge, metha- and eutheria are sisterclades, with the exclusion of prototheres. Do you have a source for that statement you make? Mesozoic genera like Eomaia are regarded basal Therians and ancestral to both metatheria and eutheria. Besides, the placenta is what make eutherians distinct from other mammals, so I do not understand your doubt on the accuracy of this article....DaMatriX 21:27, 26 April 2007 (UTC)
thread_title:  This article needs updating 

message: The following sentences are confusing:
:Eutherians are distinguished from other mammals in that the fetus is nourished during gestation via a placenta while, in general, this is not the case with other mammals (Bandicoots are a conspicuous exception to this rule.) They reproduce sexually, and the offspring are carried in the mother until fully developed. Eutherians, like the related metatherians, are viviparous.
Problems:
* One can infer that the closing parenthesis should perhaps be located at the end of the following sentence; that is, that the intent of the sentence after the parenthesized one ("They reproduced sexually . . .") is intended to discuss bandicoots. But that can't be right as bandicoots are marsupials, which means they're born before being fully developed.
* Therefore the inference is that "They reproduce sexually . . ." is intended to discuss the main subject, eutherians. But then, the sentence just before the parenthesized one says ". . . this is not the case with other mammals" so one expects that this sentence should explain how eutherians differ from other mammals. But all mammals reproduce sexually, even if all mammals aren't carried in the mother until fully developed. One way to help would be simply to remove the comma after sexually, but perhaps someone knowledgeable can further improve on this. Also note that "reproduce sexually" literally means that reproduction is not asexual, that is, it requires male and female gametes. But it could also be taken to mean that a copulatory act is required. Anomalocaris 02:43, 3 June 2007 (UTC)
replies: text: I agree, and I've clarified this with an edit. Now the eutherians are clearly distinguished between other mammal groups, and the comment about sexual reproduction was removed since it wasn't especially relevant.Twir 18:25, 24 August 2007 (UTC)
thread_title:  They reproduce sexually 

message: Some recent literature has recognized stem Eutherians (that is, non-placentals), so I added a few to the taxobox.
Also, there is much disagreement about how the major placental groups are related, and the "Epitheria" theory (that xenarthrans are the earliest-branching group) faces some strong contenders (for example, Afrotherians may have branched earliest).  So I removed Epitheria from the taxobox and listed Xenarthra as equal to the other super-orders.
Cephal-odd 01:44, 3 July 2007 (UTC)
thread_title:  Placentalia and other high-ranking taxa 

message: Placentalia is the old name for Eutheria.  Placentalia was used because the young grows in the womb connected to the placenta.  This definition is misleading because marsupialia young also develop this way to begin with but are born at a much earlier stage in developmental, hence their major development in their mother's pouch. Because of its misleading nature, placentalia was changed to eutheria.
This is the definition currently taught in zoology courses in university in Australia, like the University of Melbourne.—Preceding unsigned comment added by 220.239.209.158 (talk) 07:51, 18 September 2007 (UTC)
thread_title: Placentalia is the old term for Eutheria 

message: *Eutheria appar assumes Eutheria = Placental Mammals. Most sources they cite are about placentals.
===Definition===
*The earliest known eutherian mammal Nature 416, 816-822 (25 April 2002)  doi:10.1038/416816a
*Epipubic bones in eutherian mammals from the Late Cretaceous of Mongolia Nature 389, 483-486 (2 October 1997) doi:10.1038/39020
*(no, this is a mol phylo study of placentals Which Mammalian Supertree to Bark Up? Science 2 March 2001: Vol. 291. no. 5509, pp. 1709 - 1711 DOI: 10.1126/science.1059434 )
*(no, this is paleontologists' rejection of mol phylo hypothses of early placental radiation Cretaceous eutherians and Laurasian origin for placental mammals near the K/T boundary Nature 447, 1003-1006 (21 June 2007) | doi:10.1038/nature05854 )
-- Philcha (talk) 07:57, 24 September 2008 (UTC)
thread_title: Sources, etc.

message: *The earliest known eutherian mammal Nature 416, 816-822 (25 April 2002)  doi:10.1038/416816a
*Epipubic bones in eutherian mammals from the Late Cretaceous of Mongolia Nature 389, 483-486 (2 October 1997) doi:10.1038/39020
*(no, this is a mol phylo study of placentals Which Mammalian Supertree to Bark Up? Science 2 March 2001: Vol. 291. no. 5509, pp. 1709 - 1711 DOI: 10.1126/science.1059434 )
*(no, this is paleontologists' rejection of mol phylo hypothses of early placental radiation Cretaceous eutherians and Laurasian origin for placental mammals near the K/T boundary Nature 447, 1003-1006 (21 June 2007) | doi:10.1038/nature05854 )
-- Philcha (talk) 07:57, 24 September 2008 (UTC)
thread_title: Definition

message: I've had a go at getting Eutheria into good shape for Wikipedia Version 0.7. I doubt whether there's time to get it up to A-class or GA, but I'd hope B-class would be easy enough. Please comment.
Then we can consider the V 0.7 offer of free copyediting. 
N.B. The previous version assumed Eutheria = placentals, which is untrue (see "epipubic bones"). So we need a new article on placentals. I think I have enough info to do this in an elapsed time of about, if anyone's interested enough to comment review in time for V 0.7.
-- Philcha (talk) 13:19, 29 September 2008 (UTC)
thread_title: Please review

message: The edits from last September look good and added useful information about the fossil forms.  Now the article is about stem-eutherians, and pretty much ignores Placentalia.  For instance, the list of Placental orders has disappeared from the taxobox.  That would be an improvement if there were an article for Placentalia, but there isn't one - Placentalia currently redirects back to Eutheria.
May I suggest we restore the information about Placentalia until that taxon has its own article?
Cephal-odd (talk) 06:58, 16 February 2009 (UTC)
replies: text: I think it would be better to create a real article at Placentalia. I'm not sure how much there is to add to Eutheria, but a decent article on Placentalia would be pretty big - definition, how the placenta forms and works, pros and cons of this method of reproduction compared with egg-laying and marsupial methods, summary of modern placentals, evolutionary history. I can't offer to do it myself, as I've just fished a major revamp of Ctenophore and for a little light relief am now working on a subject not rleated to zoology or paleontology. However if anyone develops a proper article on Placentalia and asks me to comment, I will.  --Philcha (talk) 08:25, 16 February 2009 (UTC)
replies: text: I don't think making such an article would be a good idea as Eutheria is often used (when not discussing paleontology) for the placentals, so it would be better to discuss Placentalia in this article. Narayanese (talk) 20:44, 18 March 2009 (UTC)
replies: text: I think that would be confusing as well as technically incorrect. The big difference between placental and non-placental eutheria is that the non-placental ones, like all earlier therapsids, had epipubic bones which stiffened the abdomen during locomotion. This would have limited the size of the young, so non-placental eutheria probably gave birth to very "premature" young, as marsupials so. OTOH the normal idea of a placental is of an animal with a well-developed intra-uterine nutritional system that allows for the production of fairly well-developed young (especially in precocial species like the plains herbivores, whose young can stagger about immediately and can run within a few hours). --Philcha (talk) 23:00, 18 March 2009 (UTC)
thread_title:  stuff about Placentalia 

message: I undid the "contract" banner. I don't know whether Theria contradicts Eutheria, which has only 1 citation, to a simple link of eutherian taxa. However I produced most the current content of Eutheria and it's correct according to paleontology articles in top-class journals. --Philcha (talk) 21:19, 27 October 2009 (UTC)
thread_title: "Contradiction" with [[Theria]]

message: The taxobox seems to be getting a bit unwieldly, and descends through about half of the article. Might I suggest a simplification of the taxa within the box, with more detail given within the article body? The ?question mark taxa are confusing for one (e.g. by which source are they enigmatic?), and might better be explained in text. Additionally, Zhelestidae could essentially be collapsed for now since no descendent taxa have articles, and if Zalambdalestidae is monotypic it could be wikilinked to Zalambdalestes. I realize that the descendent articles for many non-placental eutherians are incongruent (e.g. Leptictida and Asioryctitheria seem to variously share genera), but I think a taxobox should be as concise and non-controversial as possible, and in some cases even "see text" is superior. Lastly, I'm in favor of a replacing the taxobox picture to a collage of modern eutherians (I can make a new one if need be, including non-placentals), rather than having a single species (Juramaia) as representative of the whole. This might better thematically "set" the article in the mind of the casual reader. The Juramaia image could be placed lower in the article within the discussion of evolution. --Animalparty-- (talk) 03:02, 8 December 2013 (UTC)
replies: text: I think that there's often an over-use of "See text" in taxoboxen, but this seems exactly the sort of case where it's appropriate and desirable. The present version is, I suspect, somewhat confusing for more casual readers. I'd agree with the use of a collage as well, much as we have at Laurasiatheria, since the article is about the group as a whole, rather than just the stem taxa and their evolution. Anaxial (talk) 07:54, 8 December 2013 (UTC)
thread_title:  Taxobox 

message: the parenthetical in the first section may need further review: (technically a misleading name, since all mammals develop a placenta[2])
The article cited seems to be arguing for an expansion of the term "placenta" rather than describing a structure fitting the more common usage of the term. From the article, "Nutrients can also be transferred between embryonic compartments that are not in direct contact with the endometrium. Therefore, the definition of a placenta should include any participation of fetal membranes in intra-uterine embryo–maternal physiological exchange." However, a more typical definition of placenta would be, "The placenta is an organ that connects the developing fetus to the uterine wall to allow nutrient uptake, waste elimination, and gas exchange via the mother's blood supply." (from the wiki page Placenta). However, in monotremes no such attachment to the endometrium is ever formed. I'm snipping it out. Dantose (talk) 20:23, 3 February 2014 (UTC)
replies: text: That's fine with me, I'm not a fan of such editorial pendantics. Placentas and placental-like structures occur in sharks as well, but this article is clearly not about them. Placental is a common name for this group of animals, and the reproductive aspects of placentals (extant eutherians) are in desperate need of coverage here.--Animalparty-- (talk) 22:44, 3 February 2014 (UTC)
thread_title:  term "Placentalia" parantetical 

message: what is the strait up definition of this category ? 
mammals have mammary glands , specialised milk glands called teets . 
eukaryotes have a cell nucleus .  
craniata have a skull .
chordata have a dorsel tube . 
what is this one ? 
nothing but endless dodgy rambling . 
any thing and every thing to dodge the question. typical Wikipedia domiatign editors . 20,000 isis terrorist kids in caves in packastan .  — Preceding unsigned comment added by 122.150.8.147 (talk) 22:07, 6 October 2018 (UTC)
thread_title:  definition of the category    

message: I have a few concerns with the first paragraph as currently phrased; it seems to me that the older version was better, but another editor disagrees, so, per WP:BRD, I'll leave it as is and request comment/consensus on the following points:
* Should we state that "Except for the North American Virginia opossum, which is a metatherian, all post-Miocene mammals indigenous to Europe, Africa, Asia, and North America north of Mexico are eutherians." This seems to me a valid and useful statement. Is there some reason why this should not be included in the article?
* Is it appropriate to state both that "all placental mammals [on all continents] are eutherians" and that "all extant eutherians are placental mammals"? The former seems redundant to the latter.
* The statement about placental mammals being indigenous to Antarctica also strikes me as one that needs qualification, given that all Antarctican placentals have been extinct for millions of years. Anaxial (talk) 19:31, 8 September 2020 (UTC)
thread_title:  Concerns with the lede 

message: The first paragraph of the Eutheria page claims that they “are more closely related to placentals than to marsupials.”
however, looking at other wiki pages (such as the page for Therians and it’s subdivisions), it seems that Eutheria is not “related” to placentals, but rather CONTAINS the classification for all placentals.
I could be wrong here, as this is not my field of study (hence why I am commenting and not editing the page).  But based on the other wiki articles, this one seems to be misleading. 2600:4041:661B:6A00:7175:5F83:5486:C319 (talk) 15:15, 17 September 2023 (UTC)
replies: text: Technically, the statement is true, in the sense that anything that is a placental is necessarily more closely related to (other) placentals than it is to marsupials, but I can see how it's ambiguous. I have rephrased it, and hopefully, it's clearer now. Thanks for pointing out the potential confusion. Anaxial (talk) 18:14, 17 September 2023 (UTC)
thread_title:  First paragraph is contradicted by other wiki pages 

message: Males in Eutheria possess a multifunctional penis capable of both urine and semen discharge. Prior to Eutheria, this capacity did not exist. This is actually a significant characteristic worth listing, correct? Drocj (talk) 06:01, 13 December 2023 (UTC)
thread_title:  Missing important characteristic?