Editing Multituberculata (section)

==Paleoecology==

===Behaviour===
Multituberculates are some of the earliest mammals to display complex social behaviours. One species, ''[[Filikomys]],'' from the Late Cretaceous of North America, engaged in multi-generational group nesting and burrowing.<ref>{{cite journal |last1=Weaver |first1=Lucas N. |last2=Varricchio |first2=David J. |last3=Sargis |first3=Eric J. |last4=Chen |first4=Meng |last5=Freimuth |first5=William J. |last6=Wilson Mantilla |first6=Gregory P. |title=Early mammalian social behaviour revealed by multituberculates from a dinosaur nesting site |journal=Nature Ecology & Evolution |date=2 November 2020 |volume=5 |issue=1 |pages=32–37 |doi=10.1038/s41559-020-01325-8 |pmid=33139921 |s2cid=226241443 }}</ref>

===Extinction===

The extinction of multituberculates has been a topic of controversy for several decades.<ref name="Wood 2010">{{Cite thesis |last=Wood |first=D. Joseph |title=The Extinction of the Multituberculates Outside North America: a Global Approach to Testing the Competition Model |type=M.S. |year=2010 |publisher=The Ohio State University |url=https://etd.ohiolink.edu/!etd.send_file?accession=osu1275595604&disposition=inline |access-date=2015-04-03 |archive-date=2015-04-08 |archive-url=https://web.archive.org/web/20150408104907/https://etd.ohiolink.edu/!etd.send_file?accession=osu1275595604&disposition=inline |url-status=dead}}</ref> After at least 88&nbsp;million years of dominance over most mammalian assemblies, multituberculates reached the peak of their diversity in the early [[Palaeocene]], before gradually declining across the final stages of the epoch and the [[Eocene]], finally disappearing in the early [[Oligocene]].<ref name="Ostrander 1984">{{cite journal |last1=Ostrander |first1=Gregg |title=The Early Oligocene (Chadronian) Raben Ranch Local Fauna, Northwest Nebraska: Multituberculata; with Comments on the Extinction of the Allotheria |journal=Transactions of the Nebraska Academy of Sciences and Affiliated Societies |date=1 January 1984 |url=https://digitalcommons.unl.edu/tnas/239/ }}</ref>

The last multituberculate species, ''[[Ectypodus childei]]'', went extinct near the end of the Eocene in North America. It is unclear why this particular species persisted for so long when all of its counterparts succumbed to replacement by rodents.<ref>{{Cite thesis |title=The Extinction of the Multituberculates Outside North America: a Global Approach to Testing the Competition Model |url=https://etd.ohiolink.edu/apexprod/rws_olink/r/1501/10?clear=10&p10_accession_num=osu1275595604 |publisher=The Ohio State University |date=2010 |language=en |first=D. Joseph |last=Wood |access-date=2023-05-19 |archive-date=2023-05-19 |archive-url=https://web.archive.org/web/20230519082943/https://etd.ohiolink.edu/apexprod/rws_olink/r/1501/10?clear=10&p10_accession_num=osu1275595604 |url-status=dead }}</ref>{{Rp|page=43}}

Traditionally, the extinction of multituberculates has been linked to the rise of [[rodents]] (and, to a lesser degree, earlier [[placental]] competitors like [[Hyopsodontidae|hyopsodonts]] and [[Plesiadapiformes]]), which supposedly [[Competitive exclusion principle|competitively excluded]] multituberculates from most mammalian faunas.<ref name="Krause 1986">{{cite book |doi=10.2113/gsrocky.24.special_paper_3.95 |chapter=Competitive exclusion and taxonomic displacement in the fossil record |title=Vertebrates, Phylogeny, and Philosophy |year=1986 |last1=Krause |first1=David W. |pages=95–117 |isbn=978-0-941570-02-2 |chapter-url=https://archive.org/details/vertebratesphylo0000unse/page/95 }}</ref>

However, the idea that multituberculates were replaced by rodents and other placentals has been criticised by several authors. For one thing, it relies on the assumption that these mammals are "inferior" to more derived placentals, and ignores the fact that rodents and multituberculates had co-existed for at least 15&nbsp;million years. According to some researchers, multituberculate "decline" is shaped by sharp extinction events, most notably after the [[Tiffanian]], where a sudden drop in diversity occurs. Finally, the youngest known multituberculates do not exemplify patterns of competitive exclusion; the Oligocene ''[[Ectypodus]]'' is a rather generalistic species, rather than a specialist. This combination of factors suggests that, rather than gradually declining due to pressure from rodents and similar placentals, multituberculates simply could not cope with climatic and vegetation changes, as well as the rise of new predatory eutherians, such as [[Miacidae|miacids]].<ref name="Ostrander 1984"/>

More recent studies show a mixed effect. Multituberculate faunas in North America and Europe do indeed decline in correlation to the introduction of rodents in these areas. However, [[Asia]]n multituberculate faunas co-existed with rodents with minimal extinction events, implying that competition was not the main cause for the extinction of Asiatic multituberculates. As a whole, it seems that Asian multituberculates, unlike North American and European species, never recovered from the [[KT event]], which allowed the evolution and propagation of rodents in the first place.<ref name="Wood 2010"/> A recent study seems to indeed indicate that eutherians recovered more quickly from the KT event than multituberculates.<ref>{{cite journal | last1 = Pires | first1 = Mathias M. | last2 = Rankin | first2 = Brian D. | last3 = Silvestro | first3 = Daniele | last4 = Quental | first4 = Tiago B. | year = 1804 | title = Diversification dynamics of mammalian clades during the K–Pg mass extinction | journal = Biology Letters | volume = 14 | issue = 9| page = 2058 | doi = 10.1098/rsbl.2018.0458 | pmid = 30258031 | pmc = 6170748 }}</ref> Conversely, another study has shown that placental radiation did not start significantly until after the decline of multituberculates.<ref name="Brocklehurst et al 2021"/>