Editing Mammal (section)

==Classification==
{{Main|Mammal classification}}
{{See also|List of placental mammals|List of monotremes and marsupials|List of mammal genera|List of mammal species}}
{{Pie chart
|caption=Over 70% of mammal species are in the orders [[Rodent]]ia, [[Chiroptera]], and [[Eulipotyphla]].
|label1=[[Rodentia]] |value1=40.5 |color1=#63aafe
|label2=[[Chiroptera]] |value2=22.2 |color2=#dd2d32
|label3=[[Eulipotyphla]] |value3=8.8 |color3=#fff58c
|label4=[[Primates]] |value4=7.8 |color4=#4ee257
|label5=[[Artiodactyla]] |value5=5.4 |color5=#fea746
|label6=[[Carnivora]] |value6=4.7 |color6=#6711ff
|label7=[[Diprotodontia]] |value7=2.3 |color7=#865357
|label8=[[Didelphimorphia]] |value8=1.9 |color8=#00ccff
|label9=[[Lagomorpha]] |value9=1.7 |color9=#a2bd90
|label10=[[Dasyuromorphia]] |value10=1.3 |color10=#ccffcc
|label11=[[Afrosoricida]] |value11=0.8 |color11=#ffff99
|label12=[[Armadillo|Cingulata]] |value12=0.3 |color12=#ff99cc
|label13=[[Macroscelidea]] |value13=0.3 |color13=#33cccc
|label14=[[Peramelemorphia]] |value14=0.3 |color14=#cc99ff
|label15=[[Perissodactyla]] |value15=0.3 |color15=#3366ff
|label16=[[Pilosa]] |value16=0.3 |color16=#99cc00
|label17=[[Scandentia]] |value17=0.3 |color17=#ffcc99
|label18=[[Shrew opossum|Paucituberculata]] |value18=0.1
|label19=[[Pholidota]] |value19=0.1
|label20=[[Hyracoidea]] |value20=0.09 |color20=#99ccff
|label21=[[Monotremata]] |value21=0.08 |color21=#ff6600
|label22=[[Sirenia]] |value22=0.06
|label23=[[Elephant|Proboscidea]] |value23=0.05 |color23=#003366
|label24=[[Dermoptera]] |value24=0.03 |color24=#ccffff
|label25=[[Monito del monte|Microbiotheria]] |value25=0.03
|label26=[[Marsupial mole|Notoryctemorphia]] |value26=0.03
|label27=[[Aardvark|Tubulidentata]] |value27=0.02
}}

Mammal classification has been through several revisions since [[Carl Linnaeus]] initially defined the class, and at present{{when|date=August 2024}}, no classification system is universally accepted. McKenna & Bell (1997) and Wilson & Reeder (2005) provide useful recent compendiums.<ref>{{cite book | vauthors = Vaughan TA, Ryan JM, Czaplewski NJ |year=2013 |chapter=Classification of Mammals |title=Mammalogy |edition=6th |publisher=Jones and Bartlett Learning |isbn=978-1-284-03209-3}}</ref> [[George Gaylord Simpson|Simpson]] (1945)<ref name=Simpson-1945>{{cite journal | vauthors = Simpson GG |author-link=George Gaylord Simpson |title=Principles of classification, and a classification of mammals |journal=[[American Museum of Natural History]] |volume=85 |year=1945}}</ref> provides [[systematics]] of mammal origins and relationships that had been taught universally until the end of the 20th&nbsp;century.
However, since 1945, a large amount of new and more detailed information has gradually been found: The [[fossil record|paleontological record]] has been recalibrated, and the intervening years have seen much debate and progress concerning the theoretical underpinnings of systematisation itself, partly through the new concept of [[cladistics]]. Though fieldwork and lab work progressively outdated Simpson's classification, it remains the closest thing to an official classification of mammals, despite its known issues.<ref name=Szalay>{{cite journal | vauthors = Szalay FS |year=1999 |title=Classification of mammals above the species level: Review |journal=Journal of Vertebrate Paleontology |volume=19 |number=1 |pages=191–195 |jstor=4523980 |doi=10.1080/02724634.1999.10011133 |issn=0272-4634}}</ref>

Most mammals, including the six most species-rich orders, belong to the placental group. The three largest orders in numbers of species are [[Rodent]]ia: [[mouse|mice]], [[rat]]s, [[porcupine]]s, [[beaver]]s, [[capybara]]s, and other gnawing mammals; [[Chiroptera]]: bats; and [[Eulipotyphla]]: [[shrew]]s, [[mole (animal)|moles]], and [[solenodon]]s. The next three biggest orders, depending on the [[biological classification]] scheme used, are the [[primate]]s: [[ape]]s, [[monkey]]s, and [[lemur]]s; [[Cetartiodactyla]]: [[whale]]s and [[even-toed ungulate]]s; and [[Carnivora]] which includes [[cat]]s, [[dog]]s, [[weasel]]s, [[bear]]s, [[Pinniped|seals]], and allies.<ref name=MSW3intro>{{MSW3 |heading=Preface and introductory material |page=xxvi |name-list-style=vanc }}</ref> According to ''[[Mammal Species of the World]]'', 5,416&nbsp;species were identified in 2006. These were grouped into 1,229&nbsp;[[genus|genera]], 153&nbsp;[[family (biology)|families]] and 29&nbsp;orders.<ref name="MSW3intro"/> In 2008, the [[International Union for Conservation of Nature]] (IUCN) completed a five-year Global Mammal Assessment for its [[IUCN Red List]], which counted 5,488&nbsp;species.<ref>{{cite web |title=Mammals |work=The IUCN Red List of Threatened Species |date=April 2010 |publisher=[[International Union for Conservation of Nature]] (IUCN) |url=https://www.iucnredlist.org/initiatives/mammals |access-date=23 August 2016 |archive-date=3 September 2016 |archive-url=https://web.archive.org/web/20160903200637/http://www.iucnredlist.org/initiatives/mammals |url-status=live }}</ref> According to research published in the ''[[Journal of Mammalogy]]'' in 2018, the number of recognised mammal species is 6,495, including 96&nbsp;recently extinct.<ref>{{cite journal | vauthors = Burgin CJ, Colella JP, Kahn PL, Upham NS |date=1 February 2018 |title=How many species of mammals are there? |journal=[[Journal of Mammalogy]] |volume=99 |issue=1 |pages=1–14 |doi=10.1093/jmammal/gyx147 |doi-access=free}}</ref>

===Definitions {{Anchor|variations}}===
<!-- This section is linked from the fossil_range parameter in the taxobox -->
The word "[[:wikt:mammal|mammal]]" is modern, from the scientific name ''Mammalia'' coined by [[Carl Linnaeus]] in 1758, derived from the [[Latin language|Latin]] ''[[wikt:mamma#Latin|mamma]]'' ("teat, pap"). In an influential 1988 paper, Timothy Rowe defined Mammalia [[phylogenetically]] as the [[crown group]] of mammals, the [[clade]] consisting of the [[most recent common ancestor]] of living [[monotreme]]s ([[echidna]]s and [[platypus]]es) and [[theria]]ns ([[marsupial]]s and [[placental]]s) and all descendants of that ancestor.<ref>{{cite journal |vauthors=Rowe T |year=1988 |title=Definition, diagnosis, and origin of Mammalia |journal=Journal of Vertebrate Paleontology |volume=8 |issue=3 |pages=241–264 |url=https://www.geo.utexas.edu/faculty/rowe/Publications/pdf/010%20Rowe%201988.pdf |doi=10.1080/02724634.1988.10011708 |bibcode=1988JVPal...8..241R |access-date=25 January 2024 |archive-date=18 January 2024 |archive-url=https://web.archive.org/web/20240118163712/http://www.geo.utexas.edu/faculty/rowe/Publications/pdf/010%20Rowe%201988.pdf |url-status=live }}</ref> Since this ancestor lived in the [[Jurassic]] period, Rowe's definition excludes all animals from the earlier [[Triassic]], despite the fact that Triassic fossils in the [[Haramiyida]] have been referred to the Mammalia since the mid-19th century.<ref>{{cite book |title=The Student's Elements of Geology | vauthors = Lyell C |author-link=Charles Lyell |year=1871 |publisher=John Murray |location=London |page=347 |url={{Google books|plainurl=yes|id=634gAQAAIAAJ|page=347}} |isbn=978-1-345-18248-4}}</ref> If Mammalia is considered as the crown group, its origin can be roughly dated as the first known appearance of animals more closely related to some extant mammals than to others. ''[[Ambondro mahabo|Ambondro]]'' is more closely related to monotremes than to therian mammals while ''[[Amphilestes]]'' and ''[[Amphitherium]]'' are more closely related to the therians; as fossils of all three genera are dated about {{ma|167|million years ago}} in the [[Middle Jurassic]], this is a reasonable estimate for the appearance of the crown group.<ref>{{cite journal |vauthors=Cifelli RL, Davis BM |title=Paleontology. Marsupial origins |journal=Science |volume=302 |issue=5652 |pages=1899–1900 |date=December 2003 |pmid=14671280 |doi=10.1126/science.1092272|s2cid=83973542 }}</ref>

[[T. S. Kemp]] has provided a more traditional definition: "[[Synapsid]]s that possess a [[dentary]]–[[squamosal bone|squamosal]] jaw articulation and [[occlusion (dentistry)|occlusion]] between upper and lower molars with a transverse component to the movement" or, equivalently in Kemp's view, the clade originating with the last common ancestor of ''[[Sinoconodon]]'' and living mammals.<ref>{{cite book |url=https://doc.rero.ch/record/200125/files/PAL_E3904.pdf |location=United Kingdom |title=The Origin and Evolution of Mammals |vauthors=Kemp TS |year=2005 |publisher=Oxford University Press |isbn=978-0-19-850760-4 |page=3 |oclc=232311794 |access-date=25 January 2024 |archive-date=26 September 2023 |archive-url=https://web.archive.org/web/20230926060152/https://doc.rero.ch/record/200125/files/PAL_E3904.pdf |url-status=live }}</ref> The earliest-known synapsid satisfying Kemp's definitions is ''[[Tikitherium]]'', dated {{ma|225|Ma}}, so the appearance of mammals in this broader sense can be given this [[Late Triassic]] date.<ref>{{cite journal |vauthors=Datta PM |year=2005 |title=Earliest mammal with transversely expanded upper molar from the Late Triassic (Carnian) Tiki Formation, South Rewa Gondwana Basin, India |journal=Journal of Vertebrate Paleontology |volume=25 |issue=1 |pages=200–207 |doi=10.1671/0272-4634(2005)025[0200:EMWTEU]2.0.CO;2|s2cid=131236175 }}</ref><ref>{{cite journal | vauthors = Luo ZX, Martin T |year=2007 |title=Analysis of Molar Structure and Phylogeny of Docodont Genera |journal=Bulletin of Carnegie Museum of Natural History |volume=39 |pages=27–47 |doi=10.2992/0145-9058(2007)39[27:AOMSAP]2.0.CO;2 |s2cid=29846648 |url=https://xa.yimg.com/kq/groups/13543816/1018125207/name/Luo+y+Martin+2007-+molar+structure+and+phylogeny+of+docodonts.pdf |access-date=8 April 2013 |archive-url=https://web.archive.org/web/20160303225517/http://xa.yimg.com/kq/groups/13543816/1018125207/name/Luo+y+Martin+2007-+molar+structure+and+phylogeny+of+docodonts.pdf |archive-date=3 March 2016 |url-status=dead }}</ref> However, this animal may have actually evolved during the Neogene.<ref name=":3">{{Cite journal |last1=Averianov |first1=Alexander O. |last2=Voyta |first2=Leonid L. |date=March 2024 |title=Putative Triassic stem mammal Tikitherium copei is a Neogene shrew |url=https://link.springer.com/10.1007/s10914-024-09703-w |journal=Journal of Mammalian Evolution |language=en |volume=31 |issue=1 |doi=10.1007/s10914-024-09703-w |issn=1064-7554}}</ref>

===Molecular classification of placentals===
[[File:OrthoMaM v10b 2019 116genera circular tree.svg|thumb|upright=1.35|Genus-level molecular phylogeny of 116 extant mammals inferred from the gene tree information of 14,509 [[coding region|coding DNA sequences]].<ref name=Scornavacca2019>{{cite journal | vauthors = Scornavacca C, Belkhir K, Lopez J, Dernat R, Delsuc F, Douzery EJ, Ranwez V | title = OrthoMaM v10: Scaling-up orthologous coding sequence and exon alignments with more than one hundred mammalian genomes | journal = Molecular Biology and Evolution | volume = 36 | issue = 4 | pages = 861–862 | date = April 2019 | pmid = 30698751 | pmc = 6445298 | doi = 10.1093/molbev/msz015 }}</ref> The major clades are coloured: marsupials (magenta), xenarthrans (orange), afrotherians (red), laurasiatherians (green), and euarchontoglirans (blue).]]

As of the early 21st century, molecular studies based on [[DNA]] analysis have suggested new relationships among mammal families. Most of these findings have been independently validated by [[retrotransposon]] [[retrotransposon marker|presence/absence data]].<ref name=Kriegs2006>{{cite journal | vauthors = Kriegs JO, Churakov G, Kiefmann M, Jordan U, Brosius J, Schmitz J | title = Retroposed elements as archives for the evolutionary history of placental mammals | journal = PLOS Biology | volume = 4 | issue = 4 | pages = e91 | date = April 2006 | pmid = 16515367 | pmc = 1395351 | doi = 10.1371/journal.pbio.0040091 | doi-access = free }}</ref> Classification systems based on molecular studies reveal three major groups or lineages of placentals—[[Afrotheria]], [[Xenarthra]] and [[Boreoeutheria]]—which [[speciation|diverged]] in the [[Cretaceous]]. The relationships between these three lineages is contentious, and all three possible hypotheses have been proposed with respect to which group is [[Basal (phylogenetics)|basal]]. These hypotheses are [[Atlantogenata]] (basal Boreoeutheria), [[Epitheria]] (basal Xenarthra) and [[Exafroplacentalia]] (basal Afrotheria).<ref name=Nishiharaetal2009>{{cite journal | vauthors = Nishihara H, Maruyama S, Okada N | title = Retroposon analysis and recent geological data suggest near-simultaneous divergence of the three superorders of mammals | journal = Proceedings of the National Academy of Sciences of the United States of America | volume = 106 | issue = 13 | pages = 5235–5240 | date = March 2009 | pmid = 19286970 | pmc = 2655268 | doi = 10.1073/pnas.0809297106 | bibcode = 2009PNAS..106.5235N | doi-access = free }}</ref> Boreoeutheria in turn contains two major lineages—[[Euarchontoglires]] and [[Laurasiatheria]].

Estimates for the divergence times between these three placental groups range from 105 to 120&nbsp;million years ago, depending on the type of DNA used (such as [[nuclear DNA|nuclear]] or [[mitochondrial DNA|mitochondrial]])<ref>{{cite journal | vauthors = Springer MS, Murphy WJ, Eizirik E, O'Brien SJ | title = Placental mammal diversification and the Cretaceous–Tertiary boundary | journal = Proceedings of the National Academy of Sciences of the United States of America | volume = 100 | issue = 3 | pages = 1056–1061 | date = February 2003 | pmid = 12552136 | pmc = 298725 | doi = 10.1073/pnas.0334222100 | bibcode = 2003PNAS..100.1056S | doi-access = free }}</ref> and varying interpretations of [[paleogeographic]] data.<ref name=Nishiharaetal2009/>
{{clear}}

Mammal phylogeny according to Álvarez-Carretero ''et al.'', 2022:<ref>{{cite journal |vauthors=Álvarez-Carretero S, Tamuri AU, Battini M, Nascimento FF, Carlisle E, Asher RJ, Yang Z, Donoghue PC, dos Reis M |display-authors=8 |title=A species-level timeline of mammal evolution integrating phylogenomic data |journal=Nature |volume= 602|issue=7896 |pages=263–267 |date=2022 |pmid= 34937052|pmc= |doi=10.1038/s41586-021-04341-1|bibcode=2022Natur.602..263A |hdl=1983/de841853-d57b-40d9-876f-9bfcf7253f12 |s2cid=245438816 |url=https://qmro.qmul.ac.uk/xmlui/handle/123456789/75979 |hdl-access=free }}</ref>

{{Clade | style=font-size:90%;line-height:70%
|label1='''Mammalia'''
|1={{Clade
  |label1=[[Yinotheria]]
  |1=[[Monotremata]] [[File:Genera mammalium Ornithorhynchus anatinus.jpg|50 px|''Ornithorhynchus anatinus'']]
  |label2=[[Theria]]
  |2={{Clade
    |label1=[[Marsupialia]]
    |1={{Clade
      |1=[[Paucituberculata]] [[File:Phylogenetic tree of marsupials derived from retroposon data (Paucituberculata).png|50 px]]
      |2={{Clade
        |1=[[Didelphimorphia]] [[File:A hand-book to the marsupialia and monotremata (Plate XXXII) (white background).jpg|50 px]]
        |label2=[[Australidelphia]]
        |2={{Clade
          |1=[[Microbiotheria]]
          |label2=[[Eomarsupialia]]
          |2={{Clade
            |label1=[[Agreodontia]]
            |1={{Clade
              |1=[[Notoryctemorphia]] [[File:Phylogenetic tree of marsupials derived from retroposon data (Notoryctemorphia).png|50 px]]
              |2={{Clade
                |1=[[Peramelemorphia]] [[File:Phylogenetic tree of marsupials derived from retroposon data (Paramelemorphia).png|50 px]]
                |2=[[Dasyuromorphia]] [[File:Phylogenetic tree of marsupials derived from retroposon data (Dasyuromorphia).png|50 px]]
                 }}
               }}
            |2=[[Diprotodontia]] [[File:A monograph of the Macropodidæ, or family of kangaroos (9398404841) white background.jpg|50 px|Macropodidæ]]
             }}
           }}
         }}
       }}
    |label2=[[Placentalia]]
    |2={{Clade
      |label1=[[Atlantogenata]]
      |1={{Clade
        |label1=[[Xenarthra]] 
        |1={{Clade
          |1=[[Cingulata]] [[File:Nine-banded-Armadillo white background.jpg|50 px|''Dasypus novemcinctus'']]
          |2=[[Pilosa]] [[File:Natural history of the animal kingdom for the use of young people (Plate XV) (Myrmecophaga tridactyla).jpg|50 px|''Myrmecophaga tridactyla'']]
           }}
        |label2=[[Afrotheria]]
        |2={{Clade
          |label1=[[Paenungulata]]
          |1={{Clade
            |1=[[Hyracoidea]] [[File:DendrohyraxEminiSmit white background.jpg|50 px]]
            |label2=[[Tethytheria]]
            |2={{Clade
              |1=[[Sirenia]] [[File:Manatee white background.jpg|50 px|''Trichechus'']]
              |2=[[Proboscidea]] [[File:Indian elephant white background.jpg|50 px|''Elephas maximus'']]
               }}
             }}
          |label2=[[Afroinsectiphilia]] 
          |2={{Clade
            |1=[[Tubulidentata]] [[File:Aardvark2 (PSF) colourised.png|50 px]]
            |label2=[[Afroinsectivora]]
            |2={{Clade
              |1=[[Macroscelidea]] [[File:Rhynchocyon chrysopygus-J Smit white background.jpg|50 px]]
              |2=[[Afrosoricida]] [[File:Potamogale velox illustration.jpg|50 px]]
               }}
             }}
           }}
         }}
      |label2=[[Boreoeutheria]]
      |2={{Clade

        |label1=[[Laurasiatheria]]
        |1={{Clade
          |1=[[Eulipotyphla]] [[File:Mole white background.jpg|50 px|Talpidae]]
          |label2=[[Scrotifera]]
          |2={{Clade
            |1=[[Chiroptera]] [[File:Vampire bat white background.jpg|50 px|Desmodontinae]]
            |label2=[[Ferungulata]]
            |2={{Clade
              |1=[[Pholidota]] [[File:FMIB 46859 Pangolin a grosse queue white background.jpeg|50 px|Manidae]]
              |2={{Clade
                |1=[[Carnivora]] [[File:Cynailurus guttata - 1818-1842 - Print - Iconographia Zoologica - Special Collections University of Amsterdam - (white background).jpg|50px|''Acinonyx jubatus'']]
                |label2=[[Euungulata]]
                |2={{Clade
                  |1=[[Perissodactyla]] [[File:Equus quagga (white background).jpg|50 px|''Equus quagga'']]
                  |2=[[Artiodactyla]] [[File:Walia ibex illustration white background.png|50 px|''Capra walie'']]
                   }}
                 }}
               }}
             }}
           }}
        |label2=[[Euarchontoglires]]
        |2={{Clade
          |1={{Clade
            |1=[[Scandentia]] [[File:Die Säugthiere in Abbildungen nach der Natur, mit Beschreibungen (Plate 34) (white background).jpg|50 px]]
            |label2=[[Glires]]
            |2={{Clade
              |1=[[Lagomorpha]] [[File:Bruno Liljefors - Hare studies 1885 white background.jpg|50 px|''Lepus'']]
              |2=[[Rodentia]] [[File:Ruskea rotta.png|50 px|''Rattus'']]
               }}
             }}
          |2={{Clade
            |label1=[[Primatomorpha]]
            |1={{Clade
              |1=[[Dermoptera]] [[File:Cynocephalus volans Brehm1883 (white background).jpg|50 px]]
              |2=[[Primate]]s [[File:Die Säugthiere in Abbildungen nach der Natur, mit Beschreibungen (Plate 8) (white background).jpg|50 px|''Cebus olivaceus'']] 
               }}
             }}
           }}
         }}
       }}
     }}
   }}
}}