View source for Eutheria

{{Short description|Clade of mammals in the subclass Theria}}
{{Further|Evolution of mammals}}
{{For|the genus of beetles|List of Cassidinae genera}}
{{Automatic taxobox
| fossil_range = {{Fossil range|Early Cretaceous|Recent|earliest=Late Jurassic}}
| image = Microtherulum oneirodes (cropped).png
| image_upright = 1.15
| image_caption = Skeleton of ''[[Microtherulum]]'', a basal eutherian from the Early Cretaceous of China
| image2 = Tupaia belangeri 68165855.jpg
| image2_caption = [[Northern treeshrew]] (''Tupaia belangeri''), a placental eutherian from Southeast Asia
| taxon = Eutheria
| authority = [[Theodore Gill|Gill]], 1872
| subdivision_ranks = Subgroups
| subdivision = see text.
| synonyms =
* Pan-Placentalia {{small|(Averianov, 2014)}}<ref>Averianov, A. O. & Lopatin, A. V. (2014) [https://www.researchgate.net/publication/270497042_High-level_systematics_of_placental_mammals_Current_status_of_the_problem "High-level systematics of placental mammals: Current status of the problem."] Biology Bulletin, 41(9), 801–816.</ref>
}}

'''Eutheria''' (from [[Ancient Greek]] εὐ- (''eú-''), meaning "true, well", and θηρίον (''thēríon''), meaning "beast", and thus, "true beasts"), also called '''Pan-Placentalia''', is the [[clade]] consisting of [[Placentalia|placental mammals]] and all [[theria]]n mammals that are more closely related to placentals than to [[marsupial]]s.

Eutherians are distinguished from non-eutherians by various [[phenotypic trait]]s of the feet, ankles, jaws and teeth. All extant eutherians lack [[epipubic bone]]s, which are present in all other living mammals (marsupials and [[monotreme]]s). This allows for expansion of the abdomen during pregnancy,<ref>{{Cite journal|title = Hypaxial Motor Patterns and the Function of Epipubic Bones in Primitive Mammals|journal = Science|date = 2003-01-17|issn = 0036-8075|pmid = 12532019|pages = 400–402|volume = 299|issue = 5605|doi = 10.1126/science.1074905|language = en|first1 = Stephen M.|last1 = Reilly|first2 = Thomas D.|last2 = White|bibcode = 2003Sci...299..400R }}</ref> though epipubic bones are present in a number of primitive eutherians.<ref>{{Cite journal |last1=Guilhon |first1=Gabby |last2=Braga |first2=Caryne |last3=Milne |first3=Nick |last4=Cerqueira |first4=Rui |date=November 2021 |title=Musculoskeletal anatomy and nomenclature of the mammalian epipubic bones |journal=Journal of Anatomy |language=en |volume=239 |issue=5 |pages=1096–1103 |doi=10.1111/joa.13489 |issn=0021-8782 |pmc=8546510 |pmid=34195985}}</ref> Eutheria was named in 1872 by [[Theodore Gill]]; in 1880, [[Thomas Henry Huxley]] defined it to encompass a more broadly defined group than Placentalia.<ref>{{cite book |last=Archibald |first=J David |url=http://www.bio.sdsu.edu/faculty/archibald/Archibald01Eutheria.pdf |title=Eutheria (Placental Mammals) |publisher=San Diego State University |location=San Diego, California}}</ref>

The earliest unambiguous eutherians are known from the Early Cretaceous [[Yixian Formation]] of China, dating around 120 million years ago.<ref>{{Citation |last=Beck |first=Robin M. D. |title=Diversity and Phylogeny of Marsupials and Their Stem Relatives (Metatheria) |date=2023 |work=American and Australasian Marsupials |pages=23–88 |editor-last=Cáceres |editor-first=Nilton C. |url=https://link.springer.com/10.1007/978-3-031-08419-5_35 |access-date=2024-08-04 |place=Cham |publisher=Springer International Publishing |language=en |doi=10.1007/978-3-031-08419-5_35 |isbn=978-3-031-08418-8 |editor2-last=Dickman |editor2-first=Christopher R.|url-access=subscription }}</ref> Two tribosphenic mammals, ''[[Durlstodon]]'' and ''[[Durlstotherium]]'' from the [[Berriasian]] age (~145–140 million years ago) of the [[Early Cretaceous]] in southern [[England]] have also been suggested to represent early eutherians.<ref name=Berriasian/><ref name=":2">{{Cite journal |last1=Martin |first1=T. A. |last2=Averianov |first2=A. O. |last3=Schultz |first3=J. A. |last4=Schwermann |first4=A. H. |year=2023 |title=A stem therian mammal from the Lower Cretaceous of Germany |journal=Journal of Vertebrate Paleontology |volume=42 |issue=6 |at=e2224848 |doi=10.1080/02724634.2023.2224848 |s2cid=260265765 |doi-access=free }}</ref> Another possible eutherian species ''[[Juramaia|Juramaia sinensis]]'' has been dated at {{ma|161}} from the early [[Late Jurassic]] ([[Oxfordian (stage)|Oxfordian]]) of China.<ref name="Juramaia_Nature_2011">{{cite journal | last=Luo |first=Z.|author2=C. Yuan |author3=Q. Meng |author4=Q. Ji | year = 2011 | title = A Jurassic eutherian mammal and divergence of marsupials and placentals | journal = [[Nature (journal)|Nature]] | volume = 476 | issue = 7361| pages = 42–45 | bibcode = 2011Natur.476..442L | doi = 10.1038/nature10291 | pmid=21866158}}</ref> However some authors have considered ''Juramaia'' as a stem [[theria]]n instead,<ref name=Berriasian>{{cite journal|last1=Sweetman|first1=S.C.|last2=Smith|first2=G.|last3=Martill|first3=D.M.|year=2017|title=Highly derived eutherian mammals from the earliest Cretaceous of southern Britain|journal=[[Acta Palaeontologica Polonica]]|volume=62|issue=4|pages=657–665|doi=10.4202/app.00408.2017|doi-access=free}}</ref><ref name=":2" /> and some sources have doubted the dating of the specimen.<ref>{{Cite journal |last1=King |first1=Benedict |last2=Beck |first2=Robin M. D. |date=2020-06-10 |title=Tip dating supports novel resolutions of controversial relationships among early mammals |journal=Proceedings of the Royal Society B: Biological Sciences |language=en |volume=287 |issue=1928 |article-number=20200943 |doi=10.1098/rspb.2020.0943 |issn=0962-8452 |pmc=7341916 |pmid=32517606}}</ref>

==Characteristics== 
[[File:Cambridge Natural History Mammalia Fig 068.png|thumb|right|170px|The entocuneiform bone]]
Distinguishing features are:
*an enlarged [[malleolus]] ("little hammer") at the bottom of the [[tibia]], the larger of the two shin bones<ref name="JiLuoYuan2002EarliestEutherian">{{cite journal 
| author=Ji, Q. 
| author2=Luo, Z-X. 
| author3=Yuan, C-X. 
| author4=Wible, J.R. 
| author5=Zhang, J-P. 
| author6=Georgi, J.A. 
| name-list-style=amp 
| title=The earliest known eutherian mammal 
| journal=Nature | volume=416 | pages=816–822 | date=April 2002 | doi=10.1038/416816a 
| pmid=11976675 
| issue=6883 
|bibcode = 2002Natur.416..816J }}</ref>
*the [[joint]] between the first [[Metatarsal bones|metatarsal bone]] and the entocuneiform bone (the innermost of the three [[cuneiform bones]]) in the foot is offset farther back than the joint between the second metatarsal and middle cuneiform bones—in metatherians these joints are level with each other<ref name="JiLuoYuan2002EarliestEutherian" />
*various features of jaws and teeth<ref name="JiLuoYuan2002EarliestEutherian" /> including: having three molars in the halves of each jaw, each upper canine having two roots, the paraconid on the last lower premolar is pronounced, the [[talonid]] region of the lower molars is narrower than the [[trigonid]].<ref name=":1" />

==Taxonomy==

Eutheria (i.e. Placentalia ''[[sensu]] lato'', Pan-Placentalia):<ref>{{cite book | last1=Zachos | first1=F. | last2=Asher | first2=R. | title=Mammalian Evolution, Diversity and Systematics | publisher=De Gruyter | year=2018 | isbn=978-3-11-034155-3 | url= | pages=271–339, mainly p. 277}}</ref><ref>{{cite book | last=Benton | first=Michael J. | title=Vertebrate Palaeontology | publisher=John Wiley & Sons | publication-place=Chichester | date=2014-10-20 | isbn=978-1-118-40755-4 | pages=443–444}}</ref><ref>{{cite book | last1=Zima | first1=Jan | last2=Macholán | first2=Miloš | title=Systém a fylogeneze savců | date=2021 | isbn=978-80-200-3215-7 | language=cs | pages=130–149| publisher=Academia }}</ref><ref>{{cite journal | last1=Lopatin | first1=Alexey V. | last2=Averianov | first2=Alexander | trans-title=Earliest Placentals: at the Dawn of Big Time |title= Древнейшие плацентарные: начало истории успеха | journal=Priroda | publisher=Akademizdatcenter Nauka | issue=4 | date=2018-04-01 | issn=0032-874X | pages=34–40 | url=https://www.researchgate.net/publication/325248664}}</ref><ref>{{cite journal | last1=Velazco | first1=Paúl M. | last2=Buczek | first2=Alexandra J. | last3=Hoffman | first3=Eva | last4=Hoffman | first4=Devin K. | last5=O'Leary | first5=Maureen A. | last6=Novacek | first6=Michael J. | title=Combined data analysis of fossil and living mammals: a Paleogene sister taxon of Placentalia and the antiquity of Marsupialia | journal=Cladistics | volume=38 | issue=3 | date=2022 | issn=0748-3007 | doi=10.1111/cla.12499 | pages=359–373| pmid=35098586 | url=https://discovery.ucl.ac.uk/id/eprint/10178921/ }}</ref><ref name=":1">{{cite journal | last1=Bi | first1=Shundong | last2=Zheng | first2=Xiaoting | last3=Wang | first3=Xiaoli | last4=Cignetti | first4=Natalie E. | last5=Yang | first5=Shiling | last6=Wible | first6=John R. | title=An Early Cretaceous eutherian and the placental-marsupial dichotomy | journal=Nature | volume=558 | issue=7710 | date=2018 | issn=1476-4687 | pmid=29899454 | doi=10.1038/s41586-018-0210-3 | pages=390–395 |s2cid=91737831 |bibcode=2018Natur.558..390B}}</ref><ref>{{cite journal | last1=Wang | first1=Hai-Bing | last2=Hoffmann | first2=Simone | last3=Wang | first3=Dian-Can | last4=Wang | first4=Yuan-Qing | title=A new mammal from the Lower Cretaceous Jehol Biota and implications for eutherian evolution | journal=Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences | volume=377 | issue=1847 | date=2022-03-28 | issn=1471-2970 | pmid=35125007 | pmc=8819371 | doi=10.1098/rstb.2021.0042 | article-number=20210042}}</ref><ref>{{cite journal |last1=Rook |first1=Deborah L. |last2=Hunter |first2=John P. |title=Rooting Around the Eutherian Family Tree: the Origin and Relations of the Taeniodonta |journal=Journal of Mammalian Evolution |year=2013 |volume=21 |doi=10.1007/s10914-013-9230-9 |pages=1–17}}</ref><ref>{{cite journal | last1=O'Leary | first1=Maureen A. | last2=Bloch | first2=Jonathan I. | last3=Flynn | first3=John J. | last4=Gaudin | first4=Timothy J. | last5=Giallombardo | first5=Andres | last6=Giannini | first6=Norberto P. | last7=Goldberg | first7=Suzann L. | last8=Kraatz | first8=Brian P. | last9=Luo | first9=Zhe-Xi | last10=Meng | first10=Jin | last11=Ni | first11=Xijun | last12=Novacek | first12=Michael J. | last13=Perini | first13=Fernando A. | last14=Randall | first14=Zachary S. | last15=Rougier | first15=Guillermo W. | last16=Sargis | first16=Eric J. | last17=Silcox | first17=Mary T. | last18=Simmons | first18=Nancy B. | last19=Spaulding | first19=Michelle | last20=Velazco | first20=Paúl M. | last21=Weksler | first21=Marcelo | last22=Wible | first22=John R. | last23=Cirranello | first23=Andrea L. | title=The Placental Mammal Ancestor and the Post–K-Pg Radiation of Placentals | journal=Science | publisher=American Association for the Advancement of Science (AAAS) | volume=339 | issue=6120 | date=2013-02-08 | issn=0036-8075 | doi=10.1126/science.1229237 | pages=662–667 |pmid=23393258 | bibcode=2013Sci...339..662O | hdl=11336/7302 |display-authors=1| hdl-access=free }}</ref><ref>{{cite book | last=Rose | first=Kenneth D. | title=The Beginning of the Age of Mammals | publisher=JHU Press | publication-place=Baltimore (Md.) | date=2006-09-26 | isbn=0-8018-8472-1 | chapter= ch. 6 and ch. 7}}</ref><ref>{{cite journal | last1=Halliday | first1=Thomas J. D. | last2=Upchurch | first2=Paul | last3=Goswami | first3=Anjali | title=Resolving the relationships of Paleocene placental mammals: Paleocene mammal phylogeny | journal=Biological Reviews | volume=92 | issue=1 | date=2017 | pmid=28075073 | pmc=6849585 | doi=10.1111/brv.12242 | pages=521–550}}</ref><ref>{{cite journal | last1=Manz | first1=Carly L. | last2=Chester | first2=Stephen G. B. | last3=Bloch | first3=Jonathan I. | last4=Silcox | first4=Mary T. | last5=Sargis | first5=Eric J. | title=New partial skeletons of Palaeocene Nyctitheriidae and evaluation of proposed euarchontan affinities | journal=Biology Letters | publisher=The Royal Society | volume=11 | issue=1 | year=2015 | issn=1744-9561 | doi=10.1098/rsbl.2014.0911 | article-number=20140911| doi-access=free | pmid=25589486 | pmc=4321154 }}</ref><ref>{{cite journal | last=Averianov | first=Alexander | title=A new eutherian mammal from the Late Cretaceous of Kazakhstan | journal=Acta Palaeontologica Polonica | date=2012 | doi=10.4202/app.2011.0143| doi-access=free }}</ref><ref>{{cite web | title=Eutheria | website=mv.helsinki.fi | date=2018-02-27 | url=https://www.mv.helsinki.fi/home/mhaaramo/metazoa/deuterostoma/chordata/synapsida/eutheria/eutheria_1.html | access-date=2023-11-13}}</ref><ref>{{cite web | title=Palaeos Vertebrates: Archaic Mammals: Creodonts | website=Palaeos | url=http://palaeos.com/vertebrates/archaic_mammals/creodonts.html | access-date=2023-11-14}}</ref>{{Excessive citations inline|date=April 2024}}
*incertae sedis:
** ?Family †[[Holoclemensiidae]]<ref>{{cite journal | last1=Cifelli | first1=Richard L. | last2=Davis | first2=Brian M. | title=Tribosphenic mammals from the Lower Cretaceous Cloverly Formation of Montana and Wyoming | journal=Journal of Vertebrate Paleontology | volume=35 | issue=3 | date=2015-05-04 | issn=0272-4634 | doi=10.1080/02724634.2014.920848 | article-number=e920848| bibcode=2015JVPal..35E0848C }}</ref>  (often considered a basal [[metatheria]]n)
** ?Genus †''[[Hyotheridium]]''<ref>{{cite book | last1=Sargis | first1=E.J. | last2=Dagosto | first2=M. | title=Mammalian Evolutionary Morphology: A Tribute to Frederick S. Szalay | publisher=Springer Netherlands | series=Vertebrate Paleobiology and Paleoanthropology | year=2008 | isbn=978-1-4020-6997-0 | url=https://books.google.com/books?id=6_n2Sr7kIO8C&pg=PA5 | access-date=2023-11-13 | page=5}}</ref><ref>{{cite journal |last=KIELAN-JAWOROWSKA |first=Z. |title=Evolution of the therian mammals in the Late Cretaceous of Asia. PART I. DELTATHERIDIIDAE (plates XXVIII-XXXV) |year=1975|pages=123, 124 |url=http://www.palaeontologia.pan.pl/Archive/1975-33_103-131_28-35.pdf |journal=Palaeontologia Polonica |volume=33 |issue=10}}</ref>
** ?Genus †''[[Endotherium]]''<ref>{{cite journal |last1=Wang |first1=Y-Q |last2=Kusuhashi |first2=Nao |last3=Jin |first3=Xun |last4=Chuan-kui |first4=LI |last5=Takeshi |first5=SETOGUCHI |last6=Chun-Ling |first6=GAO  |last7=Jin-Yuan |first7=LIU |journal=Vertebrata PalAsiatica |year=2018 |title=Reappraisal of Endotherium niinomii Shikama, 1947, a eutherian mammal from the Lower Cretaceous Fuxin Formation, Fuxin-Jinzhou Basin, Liaoning, China |url=https://www.researchgate.net/publication/225192557}}</ref>
** Genus †''[[Durlstodon]]''
** Genus †''[[Durlstotherium]]''
** Genus †''[[Microtherulum]]'' 
** Genus †''[[Sinodelphys]]'' 
** Genus †''[[Cokotherium]]'' 
** Genus †''[[Ambolestes]]''
** Genus †''[[Montanalestes]]''
** Genus †''[[Indoclemensia]]''<ref>{{cite journal | last1=Wilson Mantilla | first1=Gregory P. | last2=Renne | first2=Paul R. | last3=Samant | first3=Bandana | last4=Mohabey | first4=Dhananjay M. | last5=Dhobale | first5=Anup | last6=Tholt | first6=Andrew J. | last7=Tobin | first7=Thomas S. | last8=Widdowson | first8=Mike | last9=Anantharaman | first9=S. | last10=Dassarma | first10=Dilip Chandra | last11=Wilson Mantilla | first11=Jeffrey A. | title=New mammals from the Naskal intertrappean site and the age of India's earliest eutherians | journal=Palaeogeography, Palaeoclimatology, Palaeoecology | publisher=Elsevier BV | volume=591 | year=2022 | issn=0031-0182 | doi=10.1016/j.palaeo.2022.110857 | page=| bibcode=2022PPP...59110857W }}</ref>
** ?Family †[[Horolodectidae]] (might belong somewhere within Placentalia ''sensu stricto'')<ref>{{cite journal | last=Scott | first=Craig S | title=Horolodectidae: a new family of unusual eutherians (Mammalia: Theria) from the Palaeocene of Alberta, Canada | journal=Zoological Journal of the Linnean Society | volume=185 | issue=2 | date=2019-01-18 | issn=0024-4082 | doi=10.1093/zoolinnean/zly040 | pages=431–458}}</ref>
** ?Genus †''[[Juramaia]]''
** Genus †''[[Eomaia]]''
* Genus †''[[Acristatherium]]''
* ''Clade'' †[[Tamirtheria]] ? (monophyly disputed<ref>{{Cite journal |last1=Brady |first1=Peggy L. |last2=Castrellon Arteaga |first2=Alejandro |last3=López-Torres |first3=Sergi |last4=Springer |first4=Mark S. |date=September 2024 |title=The effects of ordered multistate morphological characters on phylogenetic analyses of eutherian mammals |journal=Journal of Mammalian Evolution |language=en |volume=31 |issue=3 |doi=10.1007/s10914-024-09727-2 |issn=1064-7554|doi-access=free }}</ref>)
** Genus †''[[Prokennalestes]]''
** ?Genus †''[[Hovurlestes]]''
** Genus †''[[Murtoilestes]]''
** Genus †''[[Bobolestes]]'' (inclusive of the former genus ''[[Otlestes]]'')
** Family †[[Adapisoriculidae]] (inclusive of the genus †''[[Sahnitherium]]'')
** Genus †''[[Paranyctoides]]''
** Family †[[Zhelestidae]] (inclusive of the genus ''[[Eozhelestes]]'')
** Family †[[Cimolestidae]] (inclusive of the genera †''[[Maelestes]]'' and †''[[Batodon]]'')
** Order †[[Asioryctitheria]] 
** Family †[[Zalambdalestidae]]
** Order †[[Leptictida]]
**?Order †[[Taeniodonta]]<ref>{{Cite thesis |last1=Kynigopoulou |first1=Zoi |last2=Brusatte |first2=Stephen |last3=Fraser |first3=Nicholas |last4=Wood |first4=Rachel |last5=Williamson |first5=Tom |last6=Shelley |first6=Steve |title=Phylogeny, evolution, and anatomy of Taeniodonta (Mammalia: Eutheria) and implications for the mammalian evolution after the Cretaceous-Palaeogene mass extinction |date=2023-06-12 |publisher=University Of Edinburgh |doi=10.7488/ERA/3414 |hdl=1842/40653}}</ref>
** ?Family †[[Didymoconidae]]
* ?Genus †''[[Purgatorius]]''
* ?Genus †''[[Protungulatum]]''
* ?Genus †''[[Oxyprimus]]''
* Infraclass [[Placentalia]] ''sensu stricto''
Notes:
* Some older systems contained an order called [[Cimolesta]] (''sensu lato''), which contains the above taxa Cimolestidae, Taeniodonta and Didymoconidae, but also (some or all of) the taxa †[[Ptolemaiidae]], †[[Palaeoryctidae]], †[[Wyolestidae]], †[[Pantolesta]], †[[Tillodontia]], †[[Apatotheria]], †[[Pantodonta]], [[Pholidota]] and †[[Palaeanodonta]]. Those additional taxa (which are usually considered members of Placentalia ''sensu stricto'') were thus also placed next to Cimolestidae, now classified as basal Eutheria. [[Creodonta]] and [[Dinocerata]] have also been suggested as basal eutherians.
* Some authors classify the taxa placed at the end of the above system as part of Placentalia ''sensu stricto''. Depending on the author, this applies to taxa placed from (and inclusive of) Leptictida or Asioryctitheria or Adapisoriculidae down to (and inclusive of) ''Oxyprimus''. Specifically, some older authors associated Cimolestidae with [[Ferae]], Zalambdalestidae with [[Glires]], Zhelestidae with [[Ungulata]], and Leptictida and Adapisoriculidae with [[Lipotyphla]] or [[Archonta]]. All of these are now considered basal Eutheria.

==Evolutionary history==
Eutheria contains several [[extinction|extinct]] [[genus|genera]] as well as larger groups, many with complicated [[taxonomy (biology)|taxonomic]] histories still not fully understood. Members of the [[Adapisoriculidae]], [[Cimolesta]] and [[Leptictida]] have been previously placed within the outdated placental group [[Insectivora]], while [[Zhelestidae|zhelestids]] have been considered primitive [[ungulate]]s.<ref name=Rose>{{cite book|last=Rose|first=Kenneth D.|title=The beginning of the age of mammals|year=2006|publisher=Johns Hopkins University Press|location=Baltimore|isbn=978-0-8018-9221-9}}</ref> However, more recent studies have suggested these enigmatic taxa represent [[crown group|stem group]] eutherians, more basal to Placentalia.<ref name=Wibleetal2007>{{cite journal|last=Wible|first=J. R.|author2=Rougier, G. W. |author3=Novacek, M. J. |author4= Asher, R. J. |title=Cretaceous eutherians and Laurasian origin for placental mammals near the K/T boundary|journal=Nature|year=2007|volume=447|issue=7147|pages=1003–1006|doi=10.1038/nature05854|pmid=17581585|bibcode = 2007Natur.447.1003W }}</ref><ref name=Wibleetal09>{{cite journal|last=Wible|first=John R.|author2=Rougier, Guillermo W. |author3=Novacek, Michael J. |author4= Asher, Robert J. |title=The Eutherian Mammal ''Maelestes gobiensis'' from the Late Cretaceous of Mongolia and the phylogeny of cretaceous eutheria|journal=Bulletin of the American Museum of Natural History|year=2009|volume=2009|issue=327 |pages=1–123|doi=10.1206/623.1|hdl=2246/6001|url=http://digitallibrary.amnh.org/bitstream/2246/6001/1/B327.pdf}}</ref> Many non-placental eutherians are thought to have been [[insectivore]]s, as is the case with many primitive mammals.<ref>{{Cite journal |last1=Morales-García |first1=Nuria Melisa |last2=Gill |first2=Pamela G. |last3=Janis |first3=Christine M. |last4=Rayfield |first4=Emily J. |date=2021-02-23 |title=Jaw shape and mechanical advantage are indicative of diet in Mesozoic mammals |journal=Communications Biology |volume=4 |issue=1 |page=242 |doi=10.1038/s42003-021-01757-3 |hdl=1983/8f5ace54-0b36-42ea-815b-2f22d5aec689 |issn=2399-3642 |pmc=7902851 |pmid=33623117 |hdl-access=free}}</ref> However, the [[Zhelestidae|zhelestids]] are thought to have been herbivorous.<ref name="gheerbrant&teodori2021">{{cite journal |last1=Gheerbrant |first1=Emmanuel |last2=Teodori |first2=Dominique |date=2021-03-24 |title=An enigmatic specialized new eutherian mammal from the Late Cretaceous of Western Europe (Northern Pyrenees) |journal=Comptes Rendus Palevol |issue=13 |doi=10.5852/cr-palevol2021v20a13 |issn=1777-571X}}</ref> Prior to the [[Cretaceous–Paleogene extinction event|Cretaceous–Paleogene (K-Pg) extinction event]], most eutherians were small and exhibited low anatomical and ecological diversity. Fossil evidence shows that the K-Pg extinction event led to a widespread increase in mammalian size and morphological diversity, with many small and medium-sized species going extinct and the surviving lineages evolving to have larger body sizes. Studies suggest that this overall increase in eutherian body size happened within a few hundred thousand years of the extinction. The extinction event also proved to be selective, as mammals with more generalized diets were more likely to survive than species with more specialized diets. In the early [[Paleocene]], eutherians experienced an increase in taxonomic diversification, another result of the extinction event, leading to the evolution of the stem-primate [[Purgatorius]], stem carnivorans [[Pristinictis]] and Ravenictis, and stem [[Proboscidea|proboscidean]] [[Eritherium]]. During this period, eutherians also expanded into new ecological roles, including specialized herbivores and carnivores. The [[Paleocene–Eocene Thermal Maximum]] further impacted eutherian morphological diversity, although the extent of its impacts is less studied.<ref>Emmerson, R. M. (2022). ''Changes in morphological disparity in eutherian mammals across the K–Pg boundary and Palaeocene–Eocene Thermal Maximum using discrete morphofunctional characters'' (MSc by Research thesis, University of Salford, UK). University of Salford Repository. <nowiki>https://salford-repository.worktribe.com/output/1330684/changes-in-morphological-disparity-in-eutherian-mammals-across-the-k-pg-boundary-and-palaeocene-eocene-thermal-maximum-using-discrete-morphofunctional-characters</nowiki></ref>

The weakly favoured cladogram favours Boreoeutheria as a basal eutherian clade as sister to the Atlantogenata.<ref>{{Cite journal|last1=Foley|first1=Nicole M.|last2=Springer|first2=Mark S.|last3=Teeling|first3=Emma C.|date=2016-07-19|title=Mammal madness: is the mammal tree of life not yet resolved? |journal=Phil. Trans. R. Soc. B |volume=371|issue=1699|article-number=20150140|doi=10.1098/rstb.2015.0140 |pmc=4920340|pmid=27325836}}</ref><ref>{{Cite journal|last1=Tarver|first1=James E.|last2=Reis|first2=Mario dos|last3=Mirarab|first3=Siavash|last4=Moran|first4=Raymond J.|last5=Parker|first5=Sean|last6=O'Reilly|first6=Joseph E.|last7=King|first7=Benjamin L.|last8=O'Connell|first8=Mary J.|last9=Asher|first9=Robert J.|date=2016-02-01|title=The Interrelationships of Placental Mammals and the Limits of Phylogenetic Inference |journal=Genome Biology and Evolution |volume=8|issue=2|pages=330–344|doi=10.1093/gbe/evv261 |pmc=4779606|pmid=26733575}}</ref><ref>{{Cite journal|last1=Esselstyn|first1=Jacob A.|last2=Oliveros|first2=Carl H.|last3=Swanson|first3=Mark T.|last4=Faircloth|first4=Brant C.|date=2017-08-26|title=Investigating Difficult Nodes in the Placental Mammal Tree with Expanded Taxon Sampling and Thousands of Ultraconserved Elements |journal=Genome Biology and Evolution |volume=9|issue=9|pages=2308–2321|doi=10.1093/gbe/evx168|pmc=5604124|pmid=28934378}}</ref>

{{clade|{{clade
    |label1=[[Atlantogenata]]
    |1={{clade
       |1=[[Xenarthra]]
       |2=[[Afrotheria]]
}}
       |label2=[[Boreoeutheria]]
       |2={{clade
           |label1=
           |1=[[Laurasiatheria]]
           |label2=
           |2=[[Euarchontoglires]]
           }}
     }}|label1=Placentalia&nbsp;&nbsp;}}
     
Phylogeny after Wang & Wang, 2023.<ref name=":0">{{Cite journal |last1=Wang |first1=Haibing |last2=Wang |first2=Yuanqing |date=2023-10-26 |title=Middle ear innovation in Early Cretaceous eutherian mammals |journal=Nature Communications |language=en |volume=14 |issue=1 |page=6831 |doi=10.1038/s41467-023-42606-7 |issn=2041-1723 |pmc=10603157 |pmid=37884521|bibcode=2023NatCo..14.6831W }}</ref>

{{clade|[[Metatheria]]|{{clade
|1={{clade
|1=†''[[Sinodelphys]]''
|2=†''[[Ambolestes]]''
}}
|2=†''[[Acristatherium]]''
|3=†''[[Microtherulum]]''
|4=†''[[Cokotherium]]''
|5={{clade
|1=†''[[Juramaia]]''
|2={{clade
|1=†''[[Eomaia]]''
|2={{clade
|1=†''[[Prokennalestes]]''
|2={{clade
|1=†''[[Murtoilestes]]''
|2={{clade
|1=†''[[Montanalestes]]''
|2={{clade
|1=†''[[Daulestes]]''
|2={{clade
|1={{clade
|1=†''[[Ukhaatherium]]''
|2={{clade
|1=†''[[Asioryctes]]''
|2=†''[[Kennalestes]]''
}}}}
|2={{clade
|1={{clade
|1=†''[[Gypsonictops]]''
|2=†''[[Cimolestes]]''
}}
|2={{clade
|1=†''[[Zalambdalestes]]''
|2={{clade
|1={{clade
|1=†''[[Aspanlestes]]''
|2={{clade
|1=†''[[Protungulatum]]''
|2=†''[[Eoungulatum]]''
}}}}
|2={{clade
|1=†''[[Leptictis]]''
|2=[[Placentalia]]
}}}}}}}}}}}}}}}}}}}}}}}}|label2='''Eutheria'''}}
Below is a phylogeny from Gheerbrant & Teodori (2021):<ref name="gheerbrant&teodori2021"/> 
{{clade|{{clade
|label1=Eutheria
|1={{clade
|1={{clade
|1=''[[Eomaia]]''
|2=''[[Prokennalestes]]''
|3=''[[Murtoilestes]]''}} 
|2={{clade
|1=''[[Bobolestes]]''
|2={{clade
|1=''[[Montanalestes]]''
|2={{clade
|1=''[[Paranyctoides]]''
|label2=[[Zhelestidae]]
|2={{clade
|1=''[[Sheikhdheilia]]''
|2={{clade
|1=''[[Lainodon]]''
|2=''[[Alostera]]''
|3={{clade
|1=''[[Eozhelestes]]''
|2=''[[Avitotherium]]''
|3=''[[Parazhelestes]]''
|4=''[[Aspanlestes]]''
|5=''[[Zhelestes]]''
|6={{clade
|1=''[[Borisodon]]''
|2=''[[Gallolestes]]''}} 
|7={{clade
|1=''[[Eoungulatum]]''
|2={{clade
|1=''[[Valentinella]]''
|2=''[[Azilestes]]''}} }} }} }} }} }} 
|3={{clade
|1={{clade
|1=''[[Bulaklestes]]''
|2=''[[Daulestes]]''
|3=''[[Uchkududon]]''}}
|2={{clade
|1={{clade
|1=''[[Cimolestes]]''
|2={{clade
|1=''[[Maelestes]]''
|2=''[[Batodon]]''}} }}
|2={{clade
|1={{clade
|1=''[[Kennalestes]]''
|2={{clade
|1=''[[Asioryctes]]''
|2=''[[Ukhaatherium]]''}} }} 
|2={{clade
|1=''[[Deccanolestes]]''
|2={{clade
|1={{clade
|1=''[[Kulbeckia]]''
|2={{clade
|1=''[[Zhangolestes]]''
|2={{clade
|1={{clade
|1=''[[Zalambdalestes]]''
|2=''[[Barunlestes]]''}}
|2={{clade
|1=''[[Alymlestes]]''
|2=''[[Mistralestes]]''}} }} }} }}
|2={{clade
|1={{clade
|1=''[[Gypsonictops]]''
|2=''[[Leptictis]]''}}
|2={{clade
|1={{clade
|1=''[[Purgatorius]]''
|2={{clade
|1=''[[Protungulatum]]''
|2=''[[Oxyprimus]]''}} }}
|2={TREE}  }} }} }} }} }} }} }} }} }} }} }}|style=|targetA={TREE}|subcladeA={{clade
|1={{clade
|1={{clade
|1=''[[Arctocyon]]''
|2={{clade
|1=''[[Vulpavus]]''
|2=''[[Miacis]]''}} }}
|2={{clade
|1=''[[Diacodexis]]''
|2={{clade
|1=''[[Hyopsodus]]''
|2={{clade
|1=''[[Meniscotherium]]''
|2=''[[Phenacodus]]''}} }} }} }} 
|2={{clade
|1={{clade
|1={{clade
|1=extant [[Placentalia]]
}}}}}}}}}}

==References==
{{Wikispecies|Eutheria}}
{{EB1911 poster|Monodelphia}}
{{Reflist|30em}}

{{Eutheria|E.|state=autocollapse}}
{{Mammals}}
{{Portal bar|Mammals}}
{{Taxonbar|from=Q17092469}}

[[Category:Eutheria| ]]
[[Category:Mammal taxonomy]]
[[Category:Oxfordian first appearances]]
[[Category:Extant Late Jurassic first appearances]]
[[Category:Taxa described in 1872]]