Editing Morganucodon (section)

==Classification==
[[File:Morganucodon watsoni life restoration.jpg|thumb|left|Life restoration of ''M. watsoni'']]
''Morganucodon'' is the [[type genus]] for the order [[Morganucodonta]], a group of generally similar mammaliaforms known from the [[Late Triassic]] to [[Late Jurassic]] epochs,<ref>{{cite journal |last1=Martin |first1=T. |last2=Averianov |first2=A. O. |last3=Jäger |first3=K. R. K. |last4=Schwermann |first4=A. H. |last5=Wings |first5=O. |title=A large morganucodontan mammaliaform from the Late Jurassic of Germany |journal=Fossil Imprint |date=2019 |volume=75 |issue=3–4 |pages=504–509 |doi=10.2478/if-2019-0030 |url=http://fi.nm.cz/wp-content/uploads/2019/12/13_Martin.pdf|doi-access=free }}</ref><ref>pages 511–512, Malcolm C. McKenna and Susan K. Bell, ''Classification of Mammals Above the Species Level'', Columbia University Press, 1997. {{ISBN|0-231-11012-X}}</ref> with one possible member (''[[Purbeckodon]]'') dating to the [[Early Cretaceous]].<ref>{{cite journal |last=Butler |first=P. M. |last2=Sigogneau-Russell |first2=D. |last3=Ensom |first3=P. C. |year=2011 |title=Possible persistence of the morganucodontans in the Lower Cretaceous Purbeck Limestone Group (Dorset, England) |journal=Cretaceous Research |volume=33 |pages=135–145 |doi=10.1016/j.cretres.2011.09.007}}</ref> All were small and likely insectivorous. ''Morganucodon'' is the best preserved and best understood member of Morganucodonta.

There is currently controversy about whether or not to classify ''Morganucodon'' as a mammal or as a non-mammalian [[Mammaliaformes|mammaliaform]]. Some researchers limit the term "mammal" to the [[crown group]] mammals, which would not include ''Morganucodon'' and its relatives. Others, however, define "mammals", as a group, by the possession of a special, secondarily evolved jaw joint between the dentary and the squamosal bones, which has replaced the primitive one between the [[Articular bone|articular]] and [[quadrate bone]]s in all modern mammalian groups. Under this definition, ''Morganucodon'' would be a mammal. Nevertheless, its lower jaw retains some of the bones found in its non-mammalian ancestors in a very reduced form rather than being composed solely of the dentary. Furthermore, the primitive reptile-like jaw joint between the articular and quadrate bones, which in modern mammals has moved into the middle ear and become part of the ear ossicles as malleus and incus, is still to be found in ''Morganucodon''.<ref>{{Cite journal | doi=10.1111/j.1096-3642.1981.tb01127.x|title = The skull of Morganucodon| journal=Zoological Journal of the Linnean Society| volume=71| pages=1–158|year = 1981|last1 = Kermack|first1 = K. A.| last2=Mussett| first2=Frances| last3=Rigney| first3=H. W.}}</ref> ''Morganucodon'' also suckled (it may have been the earliest animal to do so), had only two sets of teeth and grew rapidly to adult size and stopped growing thereafter, all typical mammalian traits.<ref name=Dykes>[https://web.archive.org/web/20040925071034/http://www.geocities.com/trevor_dykes/mammalsbasal.htm Mammals of the Mesozoic: The least mammal-like mammals]</ref>

;Phylogeny<ref>{{cite journal|last1=Close|first1=Roger A.|last2=Friedman|first2=Matt|last3=Lloyd|first3=Graeme T.|last4=Benson|first4=Roger BJ|year=2015|title=Evidence for a mid-Jurassic adaptive radiation in mammals.|journal=Current Biology|volume=25|issue=16|pages=2137–2142|doi=10.1016/j.cub.2015.06.047|pmid=26190074|doi-access=free}}</ref>
{{clade |style=font-size:95%;line-height:80%;
|label1=[[Mammaliaformes]]
|1={{clade
|1=''[[Adelobasileus]]''
|2={{clade
|1=''[[Sinoconodon]]''
|2={{clade
|1={{clade
|1='''''Morganucodon'''''
|2=''[[Megazostrodon]]''
}}
|2={{clade
|1=[[Haramiyida]]
|2={{clade
|1={{clade
|1=''[[Haldanodon]]''
|2=''[[Castorocauda]]''
}}
|2={{clade
|1=''[[Hadrocodium]]''
|2=[[Mammalia]]
}} }} }} }} }} }} }}