# Multituberculata

Multituberculata (commonly known as multituberculates, named for the multiple tubercles of their teeth) is an extinct order of rodent-like mammals with a fossil record spanning over 130 million years. They first appeared in the Middle Jurassic, and reached a peak diversity during the Late Cretaceous and Paleocene. They eventually declined from the mid-Paleocene onwards, disappearing from the known fossil record in the late Eocene. They are the most diverse order of Mesozoic mammals with more than 200 species known, ranging from mouse-sized to beaver-sized. These species occupied a diversity of ecological niches, ranging from burrow-dwelling to squirrel-like arborealism to jerboa-like hoppers. Multituberculates are usually placed as crown mammals outside either of the two main groups of living mammals, Theria — placentals and marsupials — and Monotremata, but usually as closer to Theria than to monotremes. They are considered to be closely related to Euharamiyida and Gondwanatheria as part of Allotheria.

## Description

The multituberculates had a cranial and dental anatomy superficially similar to rodents such as mice and rats, with cheek-teeth separated from the chisel-like front teeth by a wide tooth-less gap (the diasteme). Each cheek-tooth displayed several rows of small cusps (or tubercles, hence the name) that operated against similar rows in the teeth of the jaw; the exact homology of these cusps to therian ones is still a matter of debate. Unlike rodents, which have ever-growing teeth, multituberculates underwent dental replacement patterns typical of most mammals (though in at least some species the lower incisors continued to erupt long after the root's closure). Multituberculates are notable for the presence of a massive fourth lower premolar, the plagiaulacoid; other mammals, like Plesiadapiformes and diprotodontian marsupials, also have similar premolars in both upper and lower jaws, but in multituberculates this tooth is massive and the upper premolars are not modified this way. In basal multituberculates all three lower premolars were plagiaulacoids, increasing in size posteriorly, but in Cimolodonta only the fourth lower premolar remained, with the third one remaining only as a vestigial peg-like tooth, and in several taxa like taeniolabidoideans, the plagiaulacoid disappeared entirely or was reconverted into a molariform tooth.
Unlike rodents and similar therians, multituberculates had a palinal jaw stroke (front-to-back), instead of a propalinal (back-to-front) or transverse (side-to-side) one; as a consequence, their jaw musculature and cusp orientation is radically different. Palinal jaw strokes are almost entirely absent in modern mammals (with the possible exception of the dugong), but are also present in haramiyidans, argyrolagoideans and tritylodontids, the former historically united with multituberculates on that basis. Multituberculate mastication is thought to have operated in a two stroke cycle: first, food held in place by the last upper premolar was sliced by the bladelike lower pre-molars as the dentary moved orthally (upward). Then the lower jaw moved palinally, grinding the food between the molar cusp rows.
The structure of the pelvis in the Multituberculata suggests that they gave birth to tiny helpless, underdeveloped young, similar to modern marsupials, such as kangaroos. However, a 2022 study reveals that they might actually have had long gestation periods like placentals. However, in 2024, all Allotheria (including multituberculates) fell outside the crown group of Mammalia, implying that cimolodonts developed placental-like gestation (and viviparity in general) independently, rather than multituberculates and therians having a common viviparous ancestor.
At least two lineages developed hypsodonty, in which tooth enamel extends beyond the gumline: lambdopsalid taeniolabidoideans and sudamericid gondwanatheres.
Studies published in 2018 demonstrated that multituberculates had relatively complex brains, some braincase regions even absent in therian mammals.

## Evolution

Multituberculates first appear in the fossil record during the Jurassic period, and then survived and even dominated for over one hundred million years, longer than any other order of mammaliforms, including placental mammals. The earliest known multituberculates are from the Middle Jurassic (Bathonian ~166-168 million years ago) of England and Russia, including Hahnotherium and Kermackodon from the Forest Marble Formation of England, and Tashtykia and Tagaria from the Itat Formation of Russia. These forms are only known from isolated teeth, which bear close similarity to those of euharamyidans, which they are suspected to be closely related to. During the Late Jurassic and Early Cretaceous, primitive multituberculates, collectively grouped into the paraphyletic "Plagiaulacida", were abundant and widespread across Laurasia (including Europe, Asia and North America). During the Aptian stage of the Early Cretaceous, the advanced subgroup Cimolodonta appeared in North America, characterised by a reduced number of lower premolars, with a blade-like lower fourth premolar. By the early Late Cretaceous (Cenomanian) Cimolodonta had replaced all other multituberculate lineages.
During the Late Cretaceous, multituberculates experienced an adaptive radiation, corresponding with a shift towards herbivory. Multituberculates reached their peak diversity during the early Paleocene, shortly after the Cretaceous–Paleogene extinction event, but declined from the mid Paleocene onwards, likely due to competition with placental mammals such as rodents and ungulates, the group finally became extinct in the Late Eocene.
There are some isolated records of multituberculates from the Southern Hemisphere, including the cimolodontan Corriebaatar from the Early Cretaceous of Australia, and fragmentary remains from the Late Cretaceous Maevarano Formation of Madagascar. The family Ferugliotheriidae from the Late Cretaceous of South America, traditionally considered gondwanatherians, may actually be cimolodontan multituberculates.
During the Late Cretaceous and Paleocene the multituberculates radiated into a wide variety of morphotypes, including the squirrel-like arboreal ptilodonts. The peculiar shape of their last lower premolar is their most outstanding feature. These teeth were larger and more elongated than the other cheek-teeth and had an occlusive surface forming a serrated slicing blade. Though it can be assumed that this was used for crushing seeds and nuts, it is believed that most small multituberculates also supplemented their diet with insects, worms, and fruits. Tooth marks attributed to multituberculates are known on Champsosaurus fossils, indicating that at least some of these mammals were scavengers. A ptilodont that thrived in North America was Ptilodus. Thanks to the well-preserved Ptilodus specimens found in the Bighorn Basin, Wyoming, we know that these multituberculates were able to abduct and adduct their big toes, and thus that their foot mobility was similar to that of modern squirrels, which descend trees head first.
Another group of multituberculates, the taeniolabids, were heavier and more massively built, indicating that they lived a fully terrestrial life. The largest specimens weighed probably as much as 22 kg (49 lb), making them comparable in size to large rodents like the modern beaver.

## Classification

Multituberculate is generally placed within Allotheria alongside Euharamiyida, a clade of mammals known from the Middle Jurassic to Early Cretaceous of Asia and possibly Europe that possess several morphological similarities with multituberculates.
Gondwanatheria is a monophyletic group of allotherians that was diverse in the Late Cretaceous of South America, India, Madagascar and possibly Africa and occurs onwards into the Paleogene of South America and Antarctica. Their placement within Allotheria is highly controversial, with some phylogenies recovering the group as deeply nested within multituberculates, while others recover them as a distinct branch of allotherians separate from multituberculates.
In their 2001 study, Kielan-Jaworowska and Hurum found that most multituberculates could be referred to two suborders: "Plagiaulacida" and Cimolodonta. The exception is the genus Arginbaatar, which shares characteristics with both groups.
"Plagiaulacida" is paraphyletic, representing the more primitive evolutionary grade. Its members are the more basal Multituberculata. Chronologically, they ranged from perhaps the Middle Jurassic until the mid-Cretaceous. This group is further subdivided into three informal groupings: the allodontid line, the paulchoffatiid line, and the plagiaulacid line.
Cimolodonta is, apparently, a natural (monophyletic) suborder. This includes the more derived Multituberculata, which have been identified from the lower Cretaceous to the Eocene. The superfamilies Djadochtatherioidea, Taeniolabidoidea, Ptilodontoidea are recognized, as is the Paracimexomys group. Additionally, there are the families Cimolomyidae, Boffiidae, Eucosmodontidae, Kogaionidae, Microcosmodontidae and the two genera Uzbekbaatar and Viridomys. More precise placement of these types awaits further discoveries and analysis.

### Taxonomy

Subgroups :
Multituberculate phylogenetic tree
Main article: List of multituberculate species
Based on the combined works of Mikko's Phylogeny Archive and Paleofile.com.
Suborder †Plagiaulacida Simpson 1925
Genus ?†Argillomys Cifelli, Gordon & Lipka 2013
Species †Argillomys marylandensis Cifelli, Gordon & Lipka 2013
Genus ?†Janumys Eaton & Cifelli 2001
Species †Janumys erebos Eaton & Cifelli 2001
Super family †Allodontoidea Marsh 1889
Genus †?Glirodon Engelmann & Callison, 2001
Species †G. grandis Engelmann & Callison, 2001
Family †Arginbaataridae Hahn & Hahn, 1983
Genus †Arginbaatar Trofimov, 1980
Species †A. dmitrievae Trofimov, 1980
Family †Zofiabaataridae Bakker, 1992
Genus †Zofiabaatar Bakker & Carpenter, 1990
Species †Z. pulcher Bakker & Carpenter, 1990
Family †Allodontidae Marsh, 1889
Genus †Passumys Cifelli, Davis & Sames 2014
Species †Passumys angelli Cifelli, Davis & Sames 2014
Genus †Ctenacodon Marsh, 1879
Species †C. serratus Marsh, 1879
Species †C. nanus Marsh, 1881
Species †C. laticeps (Marsh, 1881) [Allodon laticeps Marsh 1881]
Species †C. scindens Simpson, 1928
Genus †Psalodon Simpson, 1926
Species †P. potens (Marsh, 1887) [Ctenacodon potens Marsh 1887]
Species †P. fortis (Marsh, 1887) Simpson 1929 [Allodon fortis Marsh 1887]
Species †P. marshi Simpson, 1929
Super family †Paulchoffatioidea Hahn 1969 sensu Hahn & Hahn 2003
Genus ?†Mojo Hahn, LePage & Wouters 1987
Species †Mojo usuratus Hahn, LePage & Wouters 1987
Genus ?†Rugosodon Yuan et al., 2013
Species †Rugosodon eurasiaticus Yuan et al., 2013
Family †Pinheirodontidae Hahn & Hahn, 1999
Genus †Bernardodon Hahn & Hahn, 1999
Species †B. atlanticus Hahn & Hahn, 1999
Species †B. sp. Hahn & Hahn, 1999
Genus †Cantalera Badiola, Canudo & Cuenca-Bescos, 2008
Species †Cantalera abadi Badiola, Canudo & Cuenca-Bescos, 2008
Genus †Ecprepaulax Hahn & Hahn, 1999
Species †E. anomala Hahn & Hahn, 1999
Genus †Gerhardodon Kielan-Jaworowska & Ensom, 1992
Species †G. purbeckensis Kielan-Jaworowska & Ensom, 1992
Genus †Iberodon Hahn & Hahn, 1999
Species †I. quadrituberculatus Hahn & Hahn, 1999
Genus †Lavocatia Canudo & Cuenca-Bescós, 1996
Species †L. alfambrensis Canudo & Cuenca-Bescós, 1996
Genus †Pinheirodon Hahn & Hahn, 1999
Species †P. pygmaeus Hahn & Hahn, 1999
Species †P. vastus Hahn & Hahn, 1999
Family †Paulchoffatiidae Hahn, 1969
Genus ?†Galveodon Hahn & Hahn, 1992
Species †G. nannothus Hahn & Hahn, 1992
Genus ?†Sunnyodon Kielan-Jaworowska & Ensom, 1992
Species †S. notleyi Kielan-Jaworowska & Ensom, 1992
subfamily †Paulchoffatiinae Hahn, 1971
Genus †Paulchoffatia Kühne, 1961
Species †P. delgador Kühne, 1961
Genus †Pseudobolodon Hahn, 1977
Species †P. oreas Hahn, 1977
Species †P. krebsi Hahn & Hahn, 1994
Genus †Henkelodon Hahn, 1987
Species †H. naias Hahn, 1987
Genus †Guimarotodon Hahn, 1969
Species †G. leiriensis Hahn, 1969
Genus †Meketibolodon (Hahn, 1978) Hahn, 1993
Species †M. robustus (Hahn, 1978) Hahn, 1993 [Pseudobolodon robusutus Hahn 1978]
Genus †Plesiochoffatia Hahn & Hahn, 1999 [Parachoffatia Hahn & Hahn 1998 non Mangold 1970]
Species †P. thoas (Hahn & Hahn, 1998) Hahn & Hahn 1999 [Parachoffatia thoa Hahn & Hahn 1998]
Species †P. peparethos (Hahn & Hahn, 1998) Hahn & Hahn 1999 [Parachoffatia peparethos Hahn & Hahn 1998]
Species †P. staphylos (Hahn & Hahn, 1998) Hahn & Hahn 1999 [Parachoffatia staphylos Hahn & Hahn 1998]
Genus †Xenachoffatia Hahn & Hahn, 1998
Species †X. oinopion Hahn & Hahn, 1998
Genus †Bathmochoffatia Hahn & Hahn, 1998
Species †B. hapax Hahn & Hahn, 1998
Genus †Kielanodon Hahn, 1987
Species †K. hopsoni Hahn, 1987
Genus †Meketichoffatia Hahn, 1993
Species †M. krausei Hahn, 1993
Genus †Renatodon Hahn, 2001
Species †Renatodon amalthea Hahn, 2001
Subfamily †Kuehneodontinae Hahn, 1971
Genus †Kuehneodon Hahn, 1969
Species †K. dietrichi Hahn, 1969
Species †K. barcasensis Hahn & Hahn, 2001
Species †K. dryas Hahn, 1977
Species †K. guimarotensis Hahn, 1969
Species †K. hahni Antunes, 1988
Species †K. simpsoni Hahn, 1969
Species †K. uniradiculatus Hahn, 1978
Plagiaulacoidea
Super family †Plagiaulacoidea Ameghino, 1894
Family †Plagiaulacidae Gill, 1872 sensu Kielan-Jaworowska & Hurum, 2001 [Bolodontidae Osborn 1887]
Genus ?†Morrisonodon Hahn & Hahn, 2004
Species †Morrisonodon brentbaatar (Bakker, 1998) Hahn & Hahn, 2004 [Ctenacodon brentbaatar Bakker, 1998]
Genus †Plagiaulax Falconer, 1857
Species †P. becklesii Falconer, 1857
Species †P. dawsoni Woodward, 1891 [Plioprion dawsoni Woodward, 1891; Loxaulax dawsoni (Woodward, 1891) Sloan, 1979]
Genus †Bolodon Owen, 1871 [Plioprion Cope, 1884]
Species †B. crassidens Owen, 1871
Species †B. falconeri Owen, 1871 [Pligiaulax falconeri Owen, 1871; Plioprion falconeri (Owen, 1871)]
Species †B. hydei Cifelli, Davis & Sames, 2014
Species †B. minor Falconer, 1857 [Pligiaulax minor Falconer, 1857; Plioprion minor (Falconer, 1857)]
Species †B. osborni Simpson, 1928 [Plioprion osborni (Simpson, 1928); Ctenacodon osborni Simpson, 1928]
Species ?†B. elongatus Simpson, 1928
Family †Eobaataridae Kielan-Jaworowska, Dashzeveg & Trofimov, 1987
Genus †Eobaatar Kielan-Jaworowska, Dashzeveg & Trofimov, 1987
Species †E. clemensi Sweetman, 2009
Species †E. hispanicus Hahn & Hahn, 1992
Species †E. magnus Kielan-Jaworowska, Dashzeveg & Trofimov, 1987
Species †E. minor Kielan-Jaworowska, Dashzeveg & Trofimov, 1987
Species †E. pajaronensis Hahn & Hahn, 2001
Genus †Hakusanobaatar Kusuhashi et al., 2008
Species †H. matsuoi Kusuhashi et al., 2008
Genus †Heishanobaatar Kusuhashi et al., 2010
Species †H. triangulus Kusuhashi et al., 2010
Genus †Iberica Badiola et al., 2011
Species †Iberica hahni Badiola et al., 2011
Genus †Liaobaatar Kusuhashi et al., 2009
Species †L. changi Kusuhashi et al., 2009
Genus †Loxaulax Simpson, 1928 [Parendotherium Crusafont Pairó & Adrover, 1966]
Species †L. valdensis (Woodward, 1911) Simpson, 1928[Dipriodon valdensis Woodward, 1911]
Species †L. herreroi (Crusafont Pairó & Adrover, 1966) [Parendotherium herreroi Crusafont Pairó & Adrover 1966]
Genus †Monobaatar Kielan-Jaworowska, Dashzeveg & Trofimov, 1987
Species †M. mimicus Kielan-Jaworowska, Dashzeveg & Trofimov, 1987
Genus †Sinobaatar Hu & Wang, 2002
Species †S. lingyuanensis Hu & Wang, 2002
Species †S. xiei Kusuhashi et al., 2009
Species †S. fuxinensis Kusuhashi et al., 2009
Genus †Tedoribaatar Kusuhashi et al., 2008
Species †T. reini Kusuhashi et al., 2008
Genus †Teutonodon Martin et al., 2016
Species †Teutonodon langenbergensis Martin et al. 2016
Family †Albionbaataridae Kielan-Jaworowska & Ensom, 1994
Genus †Albionbaatar Kielan-Jaworowska & Ensom, 1994
Species †A. denisae Kielan-Jaworowska & Ensom, 1994
Genus †Kielanobaatar Kusuhashi et al., 2010
Species †K. badaohaoensis Kusuhashi et al., 2010
Genus †Proalbionbaatar Hahn & Hahn, 1998
Species †P. plagiocyrtus Hahn & Hahn, 1998
Suborder †Gondwanatheria McKenna 1971 [Gondwanatheroidea Krause & Bonaparte 1993]
Family †Groeberiidae Patterson, 1952
Genus †Groeberia Patterson 1952
Species †G. minoprioi Ryan Patterson, 1952
Species †G. pattersoni G. G. Simpson, 1970
Genus †Klohnia Flynn & Wyss 1999
Species †K. charrieri Flynn & Wyss 1999
Species †K. major Goin et al., 2010
Genus ?†Epiklohnia Goin et al., 2010
Species †Epiklohnia verticalis Goin et al., 2010
Genus ?†Praedens Goin et al., 2010
Species †Praedens aberrans Goin et al., 2010
Family †Ferugliotheriidae Bonaparte, 1986
Genus †Ferugliotherium Bonaparte, 1986a [Vucetichia Bonaparte, 1990]
†Ferugliotherium windhauseni Bonaparte, 1986a [Vucetichia gracilis Bonaparte, 1990]
Genus †Trapalcotherium Rougier et al., 2008
†Trapalcotherium matuastensis Rougier et al., 2008
Family †Sudamericidae Scillato-Yané & Pascual, 1984 [Gondwanatheridae Bonaparte, 1986; Patagonidae Pascual & Carlini, 1987]
Genus †Greniodon Goin et al., 2012
†Greniodon sylvanicus Goin et al., 2012
Genus †Vintana Krause et al., 2014
†Vintana sertichi Krause et al., 2014
Genus †Dakshina Wilson, Das Sarama & Anantharaman, 2007
†Dakshina jederi Wilson, Das Sarama & Anantharaman, 2007
Genus †Gondwanatherium Bonaparte, 1986
†Gondwanatherium patagonicum Bonaparte, 1986
Genus †Sudamerica Scillato-Yané & Pascual, 1984
†Sudamerica ameghinoi Scillato-Yané & Pascual, 1984
Genus †Lavanify Krause et al., 1997
†Lavanify miolaka Krause et al., 1997
Genus †Bharattherium Prasad et al., 2007
†Bharattherium bonapartei Prasad et al.,, 2007
Genus †Patagonia Pascual & Carlini' 1987
†Patagonia peregrina Pascual & Carlini' 1987
Cimolodonta
Suborder †Cimolodonta McKenna, 1975
Genus ?†Allocodon non Marsh, 1881
Species †A. fortis Marsh, 1889
Species †A. lentus Marsh, 1892 [Cimolomys lentus]
Species †A. pumilis Marsh, 1892 [Cimolomys pumilus]
Species †A. rarus Marsh, 1889
Genus ?†Ameribaatar Eaton & Cifelli, 2001
Species †A. zofiae Eaton & Cifelli, 2001
Genus ?†Bubodens Wilson, 1987
Species †Bubodens magnus Wilson, 1987
Genus ?†Clemensodon Krause, 1992
Species †Clemensodon megaloba Krause, 1992 [Kimbetohia cambi, in partim]
Genus ?†Fractinus Higgins 2003
Species †Fractinus palmorum Higgins, 2003
Genus ?†Uzbekbaatar Kielan-Jaworowska & Nesov, 1992
Species †Uzbekbaatar kizylkumensis Kielan-Jaworowska & Nesov, 1992
Genus ?†Viridomys Fox 1971
Species †Viridomys orbatus Fox 1971
Family †Corriebaataridae Rich et al., 2009
Genus ?†Corriebaatar Rich et al., 2009
Species †Corriebaatar marywaltersae Rich et al., 2009
Paracimexomys group
Genus Paracimexomys Archibald, 1982
Species? †P. crossi Cifelli, 1997
Species? †P. dacicus Grigorescu & Hahn, 1989
Species? †P. oardaensis (Codrea et al., 2014) [Barbatodon oardaensis Codrea et al., 2014]
Species †P. magnus (Sahni, 1972) Archibald, 1982 [Cimexomys magnus Sahni, 1972]
Species †P. magister (Fox, 1971) Archibald, 1982 [Cimexomys magister Fox, 1971]
Species †P. perplexus Eaton & Cifelli, 2001
Species †P. robisoni Eaton & Nelson, 1991
Species †P. priscus (Lillegraven, 1969) Archibald, 1982 [Cimexomys priscus Lillegraven, 1969; genotype Paracimexomys sensu Eaton & Cifelli, 2001]
Species †P. propriscus Hunter, Heinrich & Weishampel 2010
Genus Cimexomys Sloan & Van Valen, 1965
Species †C. antiquus Fox, 1971
Species †C. gregoryi Eaton, 1993
Species †C. judithae Sahni, 1972 [Paracimexomys judithae (Sahni, 1972) Archibald, 1982]
Species †C. arapahoensis Middleton & Dewar, 2004
Species †C. minor Sloan & Van Valen, 1965
Species? †C. gratus (Jepson, 1930) Lofgren, 1995 [Cimexomys hausoi Archibald, 1983; Eucosmodon gratus Jepson, 1930; Mesodma ambigua? Jepson, 1940; Stygimus gratus Jepson, 1930]
Genus †Bryceomys Eaton, 1995
Species †B. fumosus Eaton, 1995
Species †B. hadrosus Eaton, 1995
Species †B. intermedius Eaton & Cifelli, 2001
Genus †Cedaromys Eaton & Cifelli, 2001
Species †C. bestia (Eaton & Nelson, 1991) Eaton & Cifelli, 2001 [Paracimexomys bestia Eaton & Nelson, 1991]
Species †C. hutchisoni Eaton 2002
Species †C. minimus Eaton 2009
Species †C. parvus Eaton & Cifelli, 2001
Genus †Dakotamys Eaton, 1995
Species? †D. sp. Eaton, 1995
Species †D. malcolmi Eaton, 1995
Species †D. shakespeari Eaton 2013
Family †Boffidae Hahn & Hahn, 1983 sensu Kielan-Jaworowska & Hurum 2001
Genus †Boffius Vianey-Liaud, 1979
Species †Boffius splendidus Vianey-Liaud, 1979 [Boffiidae Hahn & Hahn, 1983 sensu Kielan-Jaworowska & Hurum, 2001]
Family †Cimolomyidae Marsh, 1889 sensu Kielan-Jaworowska & Hurum, 2001
Genus †Paressodon Wilson, Dechense & Anderson, 2010
Species †Paressodon nelsoni Wilson, Dechense & Anderson, 2010
Genus †Cimolomys Marsh, 1889 [?Allacodon Marsh, 1889; Selenacodon Marsh, 1889]
Species †C. clarki Sahni, 1972
Species †C. gracilis Marsh, 1889 [Cimolomys digona Marsh, 1889; Meniscoessus brevis; Ptilodus gracilis Osborn, 1893 non Gidley 1909; Selenacodon brevis Marsh, 1889]
Species †C. trochuus Lillegraven, 1969
Species †C. milliensis Eaton, 1993a
Species ?†C. bellus Marsh, 1889
Genus ?†Essonodon Simpson, 1927
Species †E. browni Simpson, 1927 [cimolodontidae? Kielan-Jaworowska & Hurum 2001]
Genus ?†Buginbaatar Kielan-Jaworowska & Sochava, 1969
Species †Buginbaatar transaltaiensis Kielan-Jaworowska & Sochava, 1969
Genus ?†Meniscoessus Cope, 1882 [Dipriodon Marsh, 1889; Tripriodon Marsh, 1889 nomen dubium; Triprotodon Chure & McIntosh, 1989 nomen dubium; Selenacodon Marsh, 1889, Halodon Marsh, 1889, Oracodon Marsh, 1889]
Species †M. caperatus Marsh, 1889
Species †M. collomensis Lillegraven, 1987
Species †M. conquistus Cope 1882
Species †M. ferox Fox, 1971a
Species †M. intermedius Fox, 1976b
Species †M. major (Russell, 1936) [Cimolomys major Russell 1937]
Species †M. robustus (Marsh, 1889) [Dipriodon robustus Marsh 1889; Dipriodon lacunatus Marsh, 1889; Tripriodon coelatus Marsh, 1889; Meniscoessus coelatus Marsh, 1889; Selenacodon fragilis Marsh, 1889; Meniscoessus fragilis Marsh, 1889; Halodon sculptus (Marsh, 1889); Cimolomys sculptus Marsh, 1889; Meniscoessus sculptus Marsh, 1889; Oracodon anceps Marsh, 1889; Oracodon conulus Marsh, 1892; Meniscoessus borealis Simpson, 1927c; Meniscoessus greeni Wilson, 1987]
Species †M. seminoensis Eberle & Lillegraven, 1998a
Family †Kogaionidae Rãdulescu & Samson, 1996
Genus †Kogaionon Rãdulescu & Samson, 1996
Species †K. ungureanui Rãdulescu & Samson, 1996
Genus †Hainina Vianey-Liaud, 1979
Species †H. belgica Vianey-Liaud, 1979
Species †H. godfriauxi Vianey-Liaud, 1979
Species †H. pyrenaica Peláez-Campomanes, López-Martínez, Álvarez-Sierra & Daams, 2000
Species †H. vianeyae Peláez-Campomanes, López-Martínez, Álvarez-Sierra & Daams, 2000
Genus †Barbatodon Rãdulescu & Samson, 1986
Species †B. transylvanicum Rãdulescu & Samson, 1986
Family †Eucosmodontidae Jepsen, 1940 sensu Kielan-Jaworowska & Hurum, 2001 [Eucosmodontidae: Eucosmodontinae Jepsen, 1940 sensu McKenna & Bell, 1997]
Genus †Eucosmodon Matthew & Granger, 1921
Species †E. primus Granger & Simpson, 1929
Species †E. americanus Cope, 1885
Species †E. molestus Cope, 1869 [Neoplagiaulax molestus Cope, 1869]
Genus †Stygimys Sloan & Van Valen, 1965
Species †S. camptorhiza Johnston & Fox, 1984
Species †S. cupressus Fox, 1981
Species †S. kuszmauli [Eucosmodon kuszmauli]
Species †S. jepseni Simpson, 1935
Species †S. teilhardi Granger & Simpson, 1929
Family †Microcosmodontidae Holtzman & Wolberg, 1977 [Eucosmodontidae: Microcosmodontinae Holtzman & Wolberg, 1977 sensu McKenna & Bell, 1997]
Genus †PentacosmodonJepsen, 1940
Species †P. pronus Jepsen, 1940 [Djadochtatheroid? (Kielan-Jaworowska & Hurum, 2001)]
Genus †Acheronodon Archibald, 1982
Species †A. garbani Archibald, 1982
Genus †Microcosmodon Jepsen, 1930
Species †M. conus Jepsen, 1930
Species †M. rosei Krause, 1980
Species †M. arcuatus Johnston & Fox, 1984
Species †M. woodi Holtzman & Wolberg, 1977 [Eucosmodontine?]
Species †M. harleyi Weil, 1998
Superfamily †Ptilodontoidea Cope, 1887 sensu McKenna & Bell, 1997 e Kielan-Jaworowska & Hurum, 2001
Family †Cimolodontidae Marsh, 1889 sensu Kielan-Jaworowska & Hurum, 2001
Genus †Liotomus Lemoine, 1882 [Neoctenacodon Lemoine 1891]
Species? †L. marshi (Lemoine, 1882) Cope, 1884 [Neoctenacodon marshi Lemoine, 1882; Neoplagiaulax marshi (Lemoine 1882); Plagiaulax marshi (Lemoine 1882)] [Eucosmodontidae? McKenna & Bell, 1997]
Genus †Yubaatar Xu et al., 2015
Species †Yubaatar zhongyuanensis Xu et al., 2015
Genus †Anconodon Jepsen, 1940
Species? †A. lewisi (Simpson 1935) Sloan, 1987
Species †A. gibleyi (Simpson, 1935) [Ptilodus gidleyi Simpson, 1935]
Species †A. cochranensis (Russell, 1929) [Liotomus russelli (Simpson, 1935); Anconodon russelli (Simpson, 1935) Sloan, 1987; Ectopodon cochranensis (Russell, 1967)]
Genus †Cimolodon Marsh, 1889 [Nanomys Marsh, 1889, Nanomyops Marsh, 1892]
Species †C. agilis Marsh, 1889
Species †C. foxi Eaton, 2002
Species †C. gracilis Marsh, 1889
Species †C. electus Fox, 1971
Species †C. nitidus Marsh, 1889 [Allacodon rarus Marsh, 1892 sensu Clemens, 1964a; Nanomys minutus Marsh, 1889; Nanomyops minutus (Marsh, 1889) Marsh, 1892; Halodon serratus Marsh, 1889; Ptilodus serratus (Marsh, 1889) Gidley 1909]
Species †C. parvus Marsh, 1889
Species †C. peregrinus Donohue, Wilson & Breithaupt, 2013
Species †C. similis Fox, 1971
Species †C. wardi Eaton, 2006
Family Incertae sedis
Genus Neoliotomus Jepsen, 1930
Species †N. conventus Jepsen, 1930
Species †N. ultimus (Granger & Simpson, 1928)
Family †Neoplagiaulacidae Ameghino, 1890 [Ptilodontidae: Neoplagiaulacinae Ameghino, 1890 sensu McKenna & Bell, 1997]
Genus †Mesodma Jepsen, 1940
Species? †M. hensleighi Lillegraven, 1969
Species? †M. senecta Fox, 1971
Species †M. ambigua Jepsen, 1940
Species? †M. pygmaea Sloan, 1987
Species †M. formosa (Marsh, 1889) [Halodon formosus Marsh, 1889]
Species †M. primaeva (Lambe, 1902)
Species †M. thompsoni Clemens, 1964
Genus Ectypodus Matthew & Cranger, 1921 [Charlesmooria Kühne, 1969 ]
Species †E. aphronorus Sloan, 1981
Species? †E. childei Kühne, 1969
Species? †E. elaphus Scott, 2005
Species? †E. lovei (Sloan, 1966) Krishtlaka & Black, 1975
Species †E. musculus Matthew & Granger, 1921
Species †E. powelli Jepsen, 1940
Species? †E. simpsoni Jepsen, 1930
Species †E. szalayi Sloan, 1981
Species †E. tardus Jepsen, 1930
Genus †Mimetodon Jepsen, 1940
Species †M. krausei Sloan, 1981
Species †M. nanophus Holtzman, 1978 [Neoplagiaulax nanophus Holtzman, 1978]
Species †M. siberlingi(Simpson, 1935) Schiebout, 1974
Species †M. churchilli Jepsen, 1940
Genus †Neoplagiaulax Lemoine, 1882
Species †N. annae Vianey-Liaud, 1986
Species? †N. burgessi Archibald, 1982
Species †N. cimolodontoides Scott, 2005
Species †N. copei Lemoine, 1885
Species †N. donaldorum Scott & Krause, 2006
Species †N. eocaenus Lemoine, 1880
Species †N. grangeri Simpson, 1935
Species †N. hazeni Jepsen, 1940
Species †N. hunteri Krishtalka, 1973
Species †N. jepi Sloan, 1987
Species †N. kremnus Johnston & Fox, 1984
Species †N. macintyrei Slaon, 1981
Species †N. macrotomeus Wilson, 1956
Species †N. mckennai Sloan, 1987
Species †N. nelsoni Sloan, 1987
Species †N. nicolai Vianey-Liaud, 1986
Species †N. paskapooensis Scott, 2005
Species? †N. serrator Scott, 2005
Species †N. sylvani Vianey-Liaud, 1986
Genus †Parectypodus Jepsen, 1930
Species †P. armstrongi Johnston & Fox, 1984
Species? †P. corystes Scott, 2003
Species? †P. foxi Storer, 1991
Species †P. laytoni Jepsen, 1940
Species †P. lunatus Krause, 1982 [P. childei Kühne, 1969]
Species †P. simpsoni Jepsen, 1940
Species †P. sinclairi Simpson, 1935
Species †P. sloani Schiebout, 1974
Species †P. trovessartianus Cope, 1882 [P. trouessarti; Ptilodus; Mimetodon; Neoplagiaulax]
Species †P. sylviae Rigsby, 1980 [Ectypodus sylviae Rigby, 1980]
Species? †P. vanvaleni Sloan, 1981
Genus †Cernaysia Vianey-Liaud, 1986
Species †C. manueli Vianey-Liaud, 1986
Species †C. davidi Vianey-Liaud, 1986
Genus †Krauseia Vianey-Liaud, 1986
Species †K. clemensi Sloan, 1981 [Parectypodus clemensi Sloan, 1981]
Genus †XyronomysRigby, 1980
Species †X. swainae Rigby, 1980 [Xironomys (sic); ?Eucosmodontidae]
Genus †Xanclomys Rigby, 1980
Species †X. mcgrewiRigby, 1980
Genus †Mesodmops Tong & Wang, 1994
Species †M. dawsonae Tong & Wang, 1994
Family †Ptilodontidae Cope, 1887 [Ptilodontidae: Ptilodontinae Cope, 1887 sensu McKenna & Bell, 1997]
Genus †Kimbetohia Simpson, 1936
Species †K. cambi [Granger, Gregory & Colbert in Matthew, 1937, or Simpson, 1936]
Species †K. sp. cf. K. cambi
Genus †Ptilodus Cope, 1881 [Chirox Cope, 1884]
Species? †P. fractus
Species †P. kummae Krause, 1977
Species †P. gnomus Scott, Fox & Youzwyshyn, 2002 [cf. Ectypodus hazeni (Jepsen, 1940) Gazin, 1956]
Species †P. mediaevus Cope, 1881 [Ptilodus plicatus (Cope, 1884); Chirox plicatus Cope, 1884 P. ferronensis Gazin, 1941]
Species †P. montanus Douglass, 1908 [P. gracilis Gidley, 1909; P. admiralis Hay, 1930]
Species †P. tsosiensis Sloan, 1981
Species †P. wyomingensis Jepsen, 1940
Genus †Baiotomeus Krause, 1987
Species †B. douglassi Simpson, 1935 [Ptilodus; Mimetodon; Neoplagiaulax]
Species †B. lamberti Krause, 1987
Species †B. russelli Scott, Fox & Youzwyshyn, 2002
Species †B. rhothonion Scott, 2003
Genus †Prochetodon Jepsen, 1940
Species †P. cavus Jespen, 1940
Species †P. foxi Krause, 1987
Species †P. taxus Krause, 1987
Species? †P. speirsae Scott, 2004
Superfamily †Taeniolabidoidea Granger & Simpson, 1929 sensu Kielan-Jaworowska & Hurum, 2001
Genus †Prionessus Matthew & Granger, 1925
Species †P. lucifer Matthew & Granger, 1925
Family †Lambdopsalidae
Genus †Lambdopsalis Chow & Qi, 1978
Species †L. bulla Chow & Qi, 1978
Genus †Sphenopsalis Matthew, Granger & Simpson, 1928
Species †S. nobilis Matthew, Granger & Simpson, 1928
Family †Taeniolabididae Granger & Simpson, 1929
Genus †Taeniolabis Cope, 1882
Species †T. lamberti Simmons, 1987
Species †T. taoensis Cope, 1882
Genus †Kimbetopsalis
Species †K. simmonsae
Superfamily †Djadochtatherioidea Kielan-Jaworowska & Hurum, 1997 sensu Kielan-Jaworowska & Hurum, 2001[Djadochtatheria Kielan-Jaworowska & Hurum, 1997]
Genus? †Bulganbaatar Kielan-Jaworowska, 1974
Species? †B. nemegtbaataroides Kielan-Jaworowska, 1974
Genus †Nemegtbaatar Kielan-Jaworowska, 1974
Species? †N. gobiensis Kielan-Jaworowska, 1974
Family †Chulsanbaataridae Kielan-Jaworowska, 1974
Genus †Chulsanbaatar Kielan-Jaworowska, 1974
Species †C. vulgaris Kielan-Jaworowska, 1974
Family †Sloanbaataridae Kielan-Jaworowska, 1974
Genus †Kamptobaatar Kielan-Jaworowska, 1970
Species? †K. kuczynskii Kielan-Jaworowska, 1970
Genus †Nessovbaatar Kielan-Jaworowska & Hurum, 1997
Species †N. multicostatus Kielan-Jaworowska & Hurum, 1997
Genus †Sloanbaatar Kielan-Jaworowska, 1974
Species †S. mirabilis Kielan-Jaworowska, 1974 [Sloanbaatarinae]
Family †Djadochtatheriidae Kielan-Jaworowska $ Hurum, 1997
Genus †Djadochtatherium Simpson, 1925
Species †D. matthewi Simpson, 1925[Catopsalis matthewi Simpson, 1925]
Genus †Catopsbaatar Kielan-Jaworowska, 1974
Species †C. catopsaloides (Kielan-Jaworowska, 1974) Kielan-Jaworowska, 1994 [Djadochtatherium catopsaloides Kielan-Jaworowska, 1974]
Genus †Tombaatar Kielan-Jaworowska, 1974
Species †T. sabuli Rougier, Novacek & Dashzeveg, 1997
Genus †Kryptobaatar Kielan-Jaworowska, 1970 [Gobibaatar Kielan-Jaworowska, 1970, Tugrigbaatar Kielan-Jaworowska & Dashzeveg, 1978]
Species †K. saichanensis Kielan-Jaworowska & Dashzeveg, 1978 [Tugrigbaatar saichaenensis Kielan-Jaworowska & Dashzeveg, 1978??]
Species †K. dashzevegi Kielan-Jaworowska, 1970
Species †K. mandahuensis Smith, Guo & Sun, 2001
Species †K. gobiensis Kielan-Jaworowska, 1970 [Gobibaatar parvus Kielan-Jaworowska, 1970 ] :

### Phylogeny

Source:

## 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.

### Extinction

The extinction of multituberculates has been a topic of controversy for several decades. After at least 88 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.
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.$^{:43}$
Traditionally, the extinction of multituberculates has been linked to the rise of rodents (and, to a lesser degree, earlier placental competitors like hyopsodonts and Plesiadapiformes), which supposedly competitively excluded multituberculates from most mammalian faunas.
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 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 miacids.
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, Asian 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. A recent study seems to indeed indicate that eutherians recovered more quickly from the KT event than multituberculates. Conversely, another study has shown that placental radiation did not start significantly until after the decline of multituberculates.