Multituberculata

**Multituberculata** (commonly known as **multituberculates**, named for the multiple tubercles of their teeth) is an extinct taxonof rodent-like allotherian mammals that existed for approximately one hundred and sixty-six million years, the longest fossil history of any mammal lineage. They eventually declined from the late Palaeocene onwards, disappearing in the early Oligocene, though they might have lived even longer into the Miocene, if gondwanatheres are part of this group. More than 200 species are 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 outside either of the two main groups of living mammals—Theria, including placentals and marsupials, and Monotremata—but closer to Theria than to monotremes.

## 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. However, unlike rodents which have ever-growing teeth, multituberculates still underwent through dental replacement patterns typical to 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 aren't 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 gondwanatherians and 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.

During the 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 throve 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.

In Europe, another family of multituberculates were equally successful—the Kogaionidae, first discovered in Haţeg, Romania. They also developed an enlarged blade-like lower premolar. The *Hainina*, the most successful genus, was originally believed to be a ptilodont. However, more detailed analysis of this genus revealed a smaller number of dental cusps and a retained fifth premolar—a unique combination of primitive and advanced features indicating that *Hainina* were related to some Jurassic genera and that enlarged, blade-like premolars were acquired independently in Europe and North America.

Another group of multituberculates, the taeniolabids, were heavier and more massively built, indicating that they lived a fully terrestrial life. The largest specimens weighted probably as much as 100 kg, making them comparable in size to large rodents like *Castoroides*. They reached their highest diversity in Asia during the late Cretaceous and Paleocene, which suggests that they originated from there.

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.

At least two lineages developed hypsodonty, in which tooth enamel extends up beyond the gumline: lambdopsalidtaeniolabidoideans and sudamericid gondwanatheres. The latter, having been around already during the Cretaceous, are the earliest known lineage of grazing mammals. A species from the Katsuyama Dinosaur Forest Geopark may offer an even earlier example of grass-eating adaptations as it dates from the Lower Cretaceous at about 120 million years.

About 80 genera of Multituberculata are known, including *Lambdopsalis*, *Ptilodus* and *Meniscoessus*. In the northern hemisphere, during the late Cretaceous, more than half of typical land mammalian species were multituberculates.

## Classification

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 and possibly the more derived Gondwanatheria. Its members are the more basal Multituberculata, though gondwanatherians are rather derived. Chronologically, they ranged from perhaps the middle Jurassic (unnamed material), until the lower Cretaceous. This group is further subdivided into three informal groupings: the allodontid line, the paulchoffatiid line, and the plagiaulacid line.

Gondwanatheria is a monophyletic group that was diverse in the Late Cretaceous of South America, India, Madagascar and possibly Africa and occurs onwards into the Cenozoic of South America and Antarctica. Though their identity as multituberculates has been disputed, most recent phylogenetic studies recover them as the sister group to cimolodonts. There are two major families, Ferugliotheriidae and Sudamericidae, with a few taxa like *Greniodon* and *Groeberia* being uncertainly placed. *Patagonia* is the youngest multituberculate known, occurring in the Miocene of Argentina.

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

Multituberculate phylogenetic tree based off L. Xu, X. Zhang, H. Pu, S. Jia, and J. Zhang, J., and J. Meng. 2015. Largest known Mesozoic multituberculate from Eurasia and implications for multituberculate evolution and biology. Scientific Reports 5(14950):1-11 and Nicolás R. Chimento, Federico L. Agnolin and Fernando E. Novas (2015). "The bizarre 'metatherians' Groeberia and Patagonia, late surviving members of gondwanatherian mammals". Historical Biology: An International Journal of Paleobiology. 27 (5): 603–623. doi:10.1080/08912963.2014.903945.

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 ?†**Hahnodontidae** Sigogneau-Russell, 1991
		- Genus †*Hahnodon* Sigogneau-Russell, 1991
			* Species †*H. taqueti* Sigogneau-Russell, 1991 [*Hahnodon purbeckensis*]
		- Genus †*Denisodon* Hahn & Hahn,2003
			* Species †*D. moroccensis* Hahn & Hahn,2003
	+ 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 ?†*Morisonodon* Hahn & Hahn 2004
			* Species †*Morisonodon 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); *Neoplagiaulax falconeri* (Owen 1871); *Ctenacodon falconeri* (Owen 1871)]
			* Species †*B. hydei* Cifelli, Davis & Sames 2014
			* Species †*B. minor* Falconer, 1857 [*Pligiaulax minor* Falconer 1857; *Plioprion minor* (Falconer 1857); *Ctenacodon 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 all 2010
		- Genus ?†*Epiklohnia* Goin et all 2010
			* Species †*Epiklohnia verticalis* Goin et all 2010
		- Genus ?†*Praedens* Goin et all 2010
			* Species †*Praedens aberrans* Goin et all 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; E. Cret. CNA.
			* Species? †*D. sp.* (Utah, USA) 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 or Sloan, 1981]
			* Species †*E. americanus* Cope, 1885
			* Species †*E. molestus* Cope, 1869 (1886?) [*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 †*Pentacosmodon*Jepsen, 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, *Nonomyops* 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; *Nonomyops 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* Marsh, 1889
				+ Species? †*M. hensleighi*
				+ Species? †*M. senecta*
				+ Species? †*M. garfieldensis* Archibald, 1982
				+ Species? †*M. pygmaea* Sloan, 1987
				+ Species †*M. formosa* Marsh, 1889 [Halodon formosus Marsh, 1889??]
				+ Species †*M. primaeva* [Perectypodus primaeva]
				+ 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 [Neoplagiaulax sp. 3 Fox, 1990]
				+ 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 [*N. mckennaiai* Sloan, 1987 (lapsus calami)]
				+ Species †*N. nelsoni* Sloan, 1987
				+ Species †*N. nicolai* Vianey-Liaud, 1986
				+ Species †*N. paskapooensis* Scott, 2005
				+ Species? †*N. serrator* Scott, 2005 [*N. hunteri* Krishtalka, 1973 (in partim); N. sp. 1 Fox, 1990]
				+ 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 †*Xyronomys*Rigby, 1980
				+ Species †*X. swainae* Rigby, 1980 [Xironomys (sic); ?Eucosmodontidae]
			* Genus †*Xanclomys* Rigby, 1980
				+ Species †*X. mcgrewi*Rigby, 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 ; *Catopsalis catopsaloides* (Kielan-Jaworowska, 1974) Kielan-Jaworowska & Sloan, 1979]
			* 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 ]

## Paleoecology

### Evolutionary history

The multituberculates existed for about 166 or 183 million years, and are often considered the most successful, diversified, and long-lasting mammals in natural history. They first appeared in the Jurassic, or perhaps even the Triassic, survived the mass extinction in the Cretaceous, and became extinct in the early Oligocene epoch, some 35 million years ago. The oldest known species in the group is *Indobaatar zofiae* from the Jurassic of India, some 183 million years ago, and the youngest are two species, *Ectypodus lovei* and an unnamed possible neoplagiaulacid, from the late Eocene/OligoceneMedicine Pole Hills deposits of North Dakota. If gondwanatheres are multituberculates, then the clade might have survived even longer into the Colhuehuapian Miocene in South America, in the form of *Patagonia peregrina*.

*Patagonia*, the youngest known multituberculate, emerging from a hole near a *Necrolestes*, similarly the youngest known dryolestoidean.

### 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 (mid-Miocene if gondwanatherians are multituberculates). 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 have 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.

Competition between gondwanatherians and rodents and/or other Glires is untested, with a wide span of time between the youngest representatives of the former in India, Africa and Madagascar in the Maastrichtian and the first representatives of the latter in the Palaeocene, Eocene and Oligocene respectively. Co-existence between both groups is currently confirmed only in South America, *Patagonia peregrina* is thought to have been forced into a specialised fossorial niche by competition with rodents and argyrolagoidean paucituberculate marsupials, but another clade, Groeberiidae, attained its peak diversity in the mid-Oligocene, after the arrival of rodents.

### Geographic distribution

Multituberculates are mostly known from the northern continents (Laurasia), but there are various records from the southern continents (Gondwana). The group Gondwanatheria, known from Argentina, Antarctica, Madagascar, India, and possibly Tanzania, has been referred to the order in the past and, while this placement remains controversial, most recent phylogenetic studies recover them as multituberculates outside but close to Cimolodonta. Two genera, *Hahnodon*and *Denisodon*, are known from the Early Cretaceous of Morocco, but they may instead be haramiyidans. Multituberculates have also been recorded from the Late Cretaceous of Madagascar and Argentina, but this material has not been described in detail. An Australian multituberculate, *Corriebaatar*, is known from a single tooth. *Indobaatar* is known from the Kota Formation of India - then part of eastern Gondwanna - and is the oldest known multituberculate.

In the late Cretaceous, multituberculates were widespread and diverse in the northern hemisphere, and possibly across most southern landsmasses as well, making up more than half of the mammal species of typical faunas. Although several lineages became extinct during the faunal turnover at the end of the Cretaceous, multituberculates as a whole managed very successfully to cross the Cretaceous–Paleogene boundary and reached their peak of diversity during the Paleocene. They were an important component of nearly all Paleocene faunas of Europe and North America, and of some late Paleocene faunas of Asia. Multituberculates were also most diverse in size during the Paleocene, ranging from the size of a very small mouse to that of a beaver. However, in Asia, Palaeocene and Eocene multituberculates compose a very small percentage of the overall local mammalian fauna, having never managed to recover from the KT event in the same way that their North American and European counterparts did. Gondwanatheres are common in the Late Cretaceous of Madagascar and India, the Paleocene and Eocene of Seymour Island, and occur in South America from the Late Cretaceous to the Miocene.