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 declined from the mid-Paleocene onwards, finally going extinct 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, basal 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 , making them comparable in size to large rodents like the modern beaver.

Classification

Multituberculata 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

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

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

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

After Chimento et al. 2015:

Cladogram after Carvalho et al. 2025:

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 88million 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.

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. Adams et al. (2019) argued in favor of this hypothesis as rodents have a higher bite force than multituberculates, which would have given them access to harder, drier seeds which were becoming more abundant and had a greater range of food compared to multituberculates. The authors also argued rodents had was longer gestation periods and larger neonates which gave them a competitive advantage over multituberculates. In addition, they believed the diversity of new predators such as owls, creodonts, and carnivorans, also played a role in their extinction.

However, the idea that multituberculates were competitively 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 15million 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 suggests that multituberculates simply could not cope with climatic and vegetation changes, as well as the rise of new predatory eutherians, such as miacids. However, rodents probably still played a role in their decline.

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.

However, competitive replacement among North American species has been called into question by Benjamin John Burger in his 2025 study. He suggests the extinction of multituberculates in North America was correlated to the decline of boreal forests that were dominated by dawn redwoods and Chinese swamp cypress. The analysis suggested that multituberculates avoided pine and spruce-dominated forests despite having similar geographic distributions to those trees. However, Burger argues competitive replacements by seed-eating passerine birds such as songbirds, and several mammalian groups such as paromomyids, may have played a role in the extinction of multituberculates, although this requires more testing.

References

Sources