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, including placentals and marsupials, and MonotremataAgustí-Antón 2002, pp 3-4—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 to most mammals (though in at least some species the lower incisors continued to erupt long after the root's closure). Kielan-Jaworowska, Zofia, Richard L. Cifelli, and Zhe-Xi Luo (2005). ''Mammals from the Age of Dinosaurs: Origins, Evolution, and Structure ''
p. 299
/ref> 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 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.

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. 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 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.

Classification

Multituberculate is generally placed in the Allotheria alongside Euharamiyida, a clade of mammals known from the Middle Jurassic to Early Cretaceous of the Asia and possibly Europe that several morphological similarities to 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.Dykes ''Multituberculata (Cope 1884)''

Taxonomy

Based on the combined works of Mikko's Phylogeny ArchiveMikko'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 †''Galveodon nannothus, G. nannothus'' Hahn & Hahn, 1992
*** Genus ?†''Sunnyodon'' Kielan-Jaworowska & Ensom, 1992
**** Species †''Sunnyodon notleyi, S. notleyi'' Kielan-Jaworowska & Ensom, 1992
*** subfamily †Paulchoffatiinae Hahn, 1971
**** Genus †''Paulchoffatia'' Kühne, 1961
***** Species †''Paulchoffatia delgador, P. delgador'' Kühne, 1961
**** Genus †''Pseudobolodon'' Hahn, 1977
***** Species †''Pseudobolodon oreas, P. oreas'' Hahn, 1977
***** Species †''Pseudobolodon krebsi, P. krebsi'' Hahn & Hahn, 1994
**** Genus †''Henkelodon'' Hahn, 1987
***** Species †''Henkelodon naias, H. naias'' Hahn, 1987
**** Genus †''Guimarotodon'' Hahn, 1969
***** Species †''Guimarotodon leiriensis, G. leiriensis'' Hahn, 1969
**** Genus †''Meketibolodon'' (Hahn, 1978) Hahn, 1993
***** Species †''Meketibolodon robustus, M. robustus'' (Hahn, 1978) Hahn, 1993 [''Pseudobolodon robusutus'' Hahn 1978]
**** Genus †''Plesiochoffatia'' Hahn & Hahn, 1999 [''Parachoffatia'' Hahn & Hahn 1998 non Mangold 1970]
***** Species †''Plesiochoffatia thoas, P. thoas'' (Hahn & Hahn, 1998) Hahn & Hahn 1999 [''Parachoffatia thoa'' Hahn & Hahn 1998]
***** Species †''Plesiochoffatia peparethos, P. peparethos'' (Hahn & Hahn, 1998) Hahn & Hahn 1999 [''Parachoffatia peparethos'' Hahn & Hahn 1998]
***** Species †''Plesiochoffatia staphylos, P. staphylos'' (Hahn & Hahn, 1998) Hahn & Hahn 1999 [''Parachoffatia staphylos'' Hahn & Hahn 1998]
**** Genus †''Xenachoffatia'' Hahn & Hahn, 1998
***** Species †''Xenachoffatia oinopion, X. oinopion'' Hahn & Hahn, 1998
**** Genus †''Bathmochoffatia'' Hahn & Hahn, 1998
***** Species †''Bathmochoffatia hapax, B. hapax'' Hahn & Hahn, 1998
**** Genus †''Kielanodon'' Hahn, 1987
***** Species †''Kielanodon hopsoni, K. hopsoni'' Hahn, 1987
**** Genus †''Meketichoffatia'' Hahn, 1993
***** Species †''Meketichoffatia krausei, M. krausei'' Hahn, 1993
**** Genus †''Renatodon'' Hahn, 2001
***** Species †''Renatodon amalthea'' Hahn, 2001
*** Subfamily †Kuehneodontinae Hahn, 1971
**** Genus †''Kuehneodon'' Hahn, 1969
***** Species †''Kuehneodon dietrichi, K. dietrichi'' Hahn, 1969
***** Species †''Kuehneodon barcasensis, K. barcasensis'' Hahn & Hahn, 2001
***** Species †''Kuehneodon dryas, K. dryas'' Hahn, 1977
***** Species †''Kuehneodon guimarotensis, K. guimarotensis'' Hahn, 1969
***** Species †''Kuehneodon hahni, K. hahni'' Antunes, 1988
***** Species †''Kuehneodon simpsoni, K. simpsoni'' Hahn, 1969
***** Species †''Kuehneodon uniradiculatus, 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 †''Plagiaulax becklesii, P. becklesii'' Falconer, 1857
**** Species †''Plagiaulax dawsoni, P. dawsoni'' Woodward, 1891 [''Plioprion dawsoni'' Woodward, 1891; ''Loxaulax dawsoni'' (Woodward, 1891) Sloan, 1979]
*** Genus †''Bolodon'' Owen, 1871 [''Plioprion'' Cope, 1884]
**** Species †''Bolodon crassidens, B. crassidens'' Owen, 1871
**** Species †''Bolodon falconeri, B. falconeri'' Owen, 1871 [''Pligiaulax falconeri'' Owen, 1871; ''Plioprion falconeri'' (Owen, 1871)]
**** Species †''Bolodon hydei, B. hydei'' Cifelli, Davis & Sames, 2014
**** Species †''Bolodon minor, B. minor'' Falconer, 1857 [''Pligiaulax minor'' Falconer, 1857; ''Plioprion minor'' (Falconer, 1857)]
**** Species †''Bolodon osborni, B. osborni'' Simpson, 1928 [''Plioprion osborni'' (Simpson, 1928); ''Ctenacodon osborni'' Simpson, 1928]
**** Species ?†''Bolodon elongatus, B. elongatus'' Simpson, 1928
* Family †Eobaataridae Kielan-Jaworowska, Dashzeveg & Trofimov, 1987
** Genus †''Eobaatar'' Kielan-Jaworowska, Dashzeveg & Trofimov, 1987
*** Species †''Eobaatar clemensi, E. clemensi'' Sweetman, 2009
*** Species †''Eobaatar hispanicus, E. hispanicus'' Hahn & Hahn, 1992
*** Species †''Eobaatar magnus, E. magnus'' Kielan-Jaworowska, Dashzeveg & Trofimov, 1987
*** Species †''Eobaatar minor, E. minor'' Kielan-Jaworowska, Dashzeveg & Trofimov, 1987
*** Species †''Eobaatar pajaronensis, E. pajaronensis'' Hahn & Hahn, 2001
** Genus †''Hakusanobaatar'' Kusuhashi et al., 2008
*** Species †''Hakusanobaatar matsuoi, H. matsuoi'' Kusuhashi et al., 2008
** Genus †''Heishanobaatar'' Kusuhashi et al., 2010
*** Species †''Heishanobaatar triangulus, H. triangulus'' Kusuhashi et al., 2010
** Genus †''Iberica (mammal), Iberica'' Badiola et al., 2011
*** Species †''Iberica hahni'' Badiola et al., 2011
** Genus †''Liaobaatar'' Kusuhashi et al., 2009
*** Species †''Liaobaatar changi, L. changi'' Kusuhashi et al., 2009
** Genus †''Loxaulax'' Simpson, 1928 [''Parendotherium'' Crusafont Pairó & Adrover, 1966]
*** Species †''Loxaulax, L. valdensis'' (Woodward, 1911) Simpson, 1928[''Dipriodon valdensis'' Woodward, 1911]
*** Species †''Loxaulax, L. herreroi'' (Crusafont Pairó & Adrover, 1966) [''Parendotherium herreroi'' Crusafont Pairó & Adrover 1966]
** Genus †''Monobaatar'' Kielan-Jaworowska, Dashzeveg & Trofimov, 1987
*** Species †''Monobaatar, M. mimicus'' Kielan-Jaworowska, Dashzeveg & Trofimov, 1987
** Genus †''Sinobaatar'' Hu & Wang, 2002
*** Species †''Sinobaatar, S. lingyuanensis'' Hu & Wang, 2002
*** Species †''Sinobaatar, S. xiei'' Kusuhashi et al., 2009
*** Species †''Sinobaatar, S. fuxinensis'' Kusuhashi et al., 2009
** Genus †''Tedoribaatar'' Kusuhashi et al., 2008
*** Species †''Tedoribaatar reini, 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 †''Albionbaatar denisae, A. denisae'' Kielan-Jaworowska & Ensom, 1994
** Genus †''Kielanobaatar'' Kusuhashi et al., 2010
*** Species †''Kielanobaatar badaohaoensis, K. badaohaoensis'' ''Kusuhashi et al.'', 2010
** Genus †''Proalbionbaatar'' Hahn & Hahn, 1998
*** Species †''Proalbionbaatar plagiocyrtus, P. plagiocyrtus'' Hahn & Hahn, 1998
* Suborder †Gondwanatheria McKenna 1971 [Gondwanatheroidea Krause & Bonaparte 1993]
** Family †Groeberiidae Patterson, 1952
*** Genus †''Groeberia'' Patterson 1952
**** Species †''Groeberia minoprioi, G. minoprioi'' Ryan Patterson (biologist), Ryan Patterson, 1952
**** Species †''Groeberia pattersoni, G. pattersoni'' G. G. Simpson, 1970
*** Genus †''Klohnia'' Flynn & Wyss 1999
**** Species †''Klohnia charrieri, K. charrieri'' Flynn & Wyss 1999
**** Species †''Klohnia major, 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 (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 (mammal), Patagonia'' Pascual & Carlini' 1987
**** †''Patagonia peregrina'' Pascual & Carlini' 1987

* Suborder † Cimolodonta McKenna, 1975
** Genus ?†''Allocodon'' non Marsh, 1881
*** Species †''Allocodon fortis, A. fortis'' Marsh, 1889
*** Species †''Allocodon lentus, A. lentus'' Marsh, 1892 [''Cimolomys lentus'']
*** Species †''Allocodon pumilis, A. pumilis'' Marsh, 1892 [''Cimolomys pumilus'']
*** Species †''Allocodon rarus, A. rarus'' Marsh, 1889
** Genus ?†''Ameribaatar'' Eaton & Cifelli, 2001
*** Species †''Ameribaatar zofiae, 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? †''Paracimexomys crossi, P. crossi'' Cifelli, 1997
**** Species? †''Paracimexomys dacicus, P. dacicus'' Grigorescu & Hahn, 1989
**** Species? †''Paracimexomys oardaensis, P. oardaensis'' (Codrea et al., 2014) [''Barbatodon oardaensis'' Codrea et al., 2014]
**** Species †''Paracimexomys magnus, P. magnus'' (Sahni, 1972) Archibald, 1982 [''Cimexomys magnus'' Sahni, 1972]
**** Species †''Paracimexomys magister, P. magister'' (Fox, 1971) Archibald, 1982 [''Cimexomys magister'' Fox, 1971]
**** Species †''Paracimexomys perplexus, P. perplexus'' Eaton & Cifelli, 2001
**** Species †''Paracimexomys robinsoni, P. robisoni'' Eaton & Nelson, 1991
**** Species †''Paracimexomys priscus, P. priscus'' (Lillegraven, 1969) Archibald, 1982 [''Cimexomys priscus'' Lillegraven, 1969; genotype Paracimexomys sensu Eaton & Cifelli, 2001]
**** Species †''Paracimexomys propriscus, P. propriscus'' Hunter, Heinrich & Weishampel 2010
*** Genus ''Cimexomys'' Sloan & Van Valen, 1965
**** Species †''Cimexomys antiquus, C. antiquus'' Fox, 1971
**** Species †''Cimexomys" gregoryi, C. gregoryi'' Eaton, 1993
**** Species †''Cimexomys judithae, C. judithae'' Sahni, 1972 [''Paracimexomys judithae'' (Sahni, 1972) Archibald, 1982]
**** Species †''Cimexomys arapahoensis, C. arapahoensis'' Middleton & Dewar, 2004
**** Species †''Cimexomys minor, C. minor'' Sloan & Van Valen, 1965
**** Species? †''Cimexomys gratus, 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 †''Bryceomys fumosus, B. fumosus'' Eaton, 1995
**** Species †''Bryceomys hadrosus, B. hadrosus'' Eaton, 1995
**** Species †''Bryceomys intermedius, B. intermedius'' Eaton & Cifelli, 2001
*** Genus †''Cedaromys'' Eaton & Cifelli, 2001
**** Species †''Cedaromys bestia, C. bestia'' (Eaton & Nelson, 1991) Eaton & Cifelli, 2001 [''Paracimexomys bestia'' Eaton & Nelson, 1991]
**** Species †''Cedaromys hutchisoni, C. hutchisoni'' Eaton 2002
**** Species †''Cedaromys minimus, C. minimus'' Eaton 2009
**** Species †''Cedaromys parvus, C. parvus'' Eaton & Cifelli, 2001
*** Genus †''Dakotamys'' Eaton, 1995
**** Species? †''D. sp.'' Eaton, 1995
**** Species †''Dakotamys malcolmi, D. malcolmi'' Eaton, 1995
**** Species †''Dakotamys shakespeari, 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 †''Cimolomys clarki, C. clarki'' Sahni, 1972
**** Species †''Cimolomys gracilis, C. gracilis'' Marsh, 1889 [''Cimolomys digona'' Marsh, 1889; ''Meniscoessus brevis''; ''Ptilodus gracilis'' Osborn, 1893 non Gidley 1909; ''Selenacodon brevis'' Marsh, 1889]
**** Species †''Cimolomys trochuus, C. trochuus'' Lillegraven, 1969
**** Species †''Cimolomys milliensis, C. milliensis'' Eaton, 1993a
**** Species ?†''Cimolomys bellus, C. bellus'' Marsh, 1889
*** Genus ?†''Essonodon'' Simpson, 1927
**** Species †''Essonodon browni, 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 †''Meniscoessus caperatus, M. caperatus'' Marsh, 1889
**** Species †''Meniscoessus collomensis, M. collomensis'' Lillegraven, 1987
**** Species †''Meniscoessus conquistus, M. conquistus'' Cope 1882
**** Species †''Meniscoessus ferox, M. ferox'' Fox, 1971a
**** Species †''Meniscoessus intermedius, M. intermedius'' Fox, 1976b
**** Species †''Meniscoessus major, M. major'' (Russell, 1936) [''Cimolomys major'' Russell 1937]
**** Species †''Meniscoessus robustus, 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 †''Meniscoessus seminoensis, M. seminoensis'' Eberle & Lillegraven, 1998a
** Family † Kogaionidae Rãdulescu & Samson, 1996
*** Genus †''Kogaionon'' Rãdulescu & Samson, 1996
**** Species †''Kogaionon ungureanui, K. ungureanui'' Rãdulescu & Samson, 1996
*** Genus †''Hainina'' Vianey-Liaud, 1979
**** Species †''Hainina belgica, H. belgica'' Vianey-Liaud, 1979
**** Species †''Hainina godfriauxi, H. godfriauxi'' Vianey-Liaud, 1979
**** Species †''Hainina pyrenaica, H. pyrenaica'' Peláez-Campomanes, López-Martínez, Álvarez-Sierra & Daams, 2000
**** Species †''Hainina vianeyae, H. vianeyae'' Peláez-Campomanes, López-Martínez, Álvarez-Sierra & Daams, 2000
*** Genus †''Barbatodon'' Rãdulescu & Samson, 1986
**** Species †''Barbatodon transylvanicum, 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 †''Eucosmodon primus, E. primus'' Granger & Simpson, 1929
**** Species †''Eucosmodon americanus, E. americanus'' Cope, 1885
**** Species †''Eucosmodon molestus, E. molestus'' Cope, 1869 [''Neoplagiaulax molestus'' Cope, 1869]
*** Genus †''Stygimys'' Sloan & Van Valen, 1965
**** Species †''Stygimys camptorhiza, S. camptorhiza'' Johnston & Fox, 1984
**** Species †''Stygimys cupressus, S. cupressus'' Fox, 1981
**** Species †''Stygimys kuszmauli, S. kuszmauli'' [''Eucosmodon kuszmauli'']
**** Species †''Stygimys jepseni, S. jepseni'' Simpson, 1935
**** Species †''Stygimys teilhardi, S. teilhardi'' Granger & Simpson, 1929
** Family † Microcosmodontidae Holtzman & Wolberg, 1977 [Eucosmodontidae: Microcosmodontinae Holtzman & Wolberg, 1977 sensu McKenna & Bell, 1997]
*** Genus †''Pentacosmodon''Jepsen, 1940
**** Species †''Pentacosmodon pronus, P. pronus'' Jepsen, 1940 [Djadochtatheroid? (Kielan-Jaworowska & Hurum, 2001)]
*** Genus †''Acheronodon'' Archibald, 1982
**** Species †''Acheronodon garbani, A. garbani'' Archibald, 1982
*** Genus †''Microcosmodon'' Jepsen, 1930
**** Species †''Microcosmodon conus, M. conus'' Jepsen, 1930
**** Species †''Microcosmodon rosei, M. rosei'' Krause, 1980
**** Species †''Microcosmodon arcuatus, M. arcuatus'' Johnston & Fox, 1984
**** Species †''Microcosmodon woodi, M. woodi'' Holtzman & Wolberg, 1977 [Eucosmodontine?]
**** Species †''Microcosmodon harleyi, 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? †''Liotomus marshi, 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? †''Anconodon lewisi, A. lewisi'' (Simpson 1935) Sloan, 1987
***** Species †''Anconodon gibleyi, A. gibleyi'' (Simpson, 1935) [''Ptilodus gidleyi'' Simpson, 1935]
***** Species †''Anconodon cochraensis, 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 †''Cimolodon agilis, C. agilis'' Marsh, 1889
***** Species †''Cimolodon foxi, C. foxi'' Eaton, 2002
***** Species †''Cimolodon gracilis, C. gracilis'' Marsh, 1889
***** Species †''Cimolodon electus, C. electus'' Fox, 1971
***** Species †''Cimolodon nitidus, 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 †''Cimolodon parvus, C. parvus'' Marsh, 1889
***** Species †''Cimolodon peregrinus, C. peregrinus'' Donohue, Wilson & Breithaupt, 2013
***** Species †''Cimolodon similis, C. similis'' Fox, 1971
***** Species †''Cimolodon wardi, C. wardi'' Eaton, 2006
*** Family ''Incertae sedis''
**** Genus ''Neoliotomus'' Jepsen, 1930
***** Species †''Neoliotomus conventus, N. conventus'' Jepsen, 1930
***** Species †''Neoliotomus ultimus, N. ultimus'' (Granger & Simpson, 1928)
*** Family †Neoplagiaulacidae Ameghino, 1890 [Ptilodontidae: Neoplagiaulacinae Ameghino, 1890 sensu McKenna & Bell, 1997]
**** Genus †''Mesodma'' Jepsen, 1940
***** Species? †''Mesodma hensleighi, M. hensleighi'' Lillegraven, 1969
***** Species? †''Mesodma senecta, M. senecta'' Fox, 1971
***** Species †''Mesodma ambigua, M. ambigua'' Jepsen, 1940
***** Species? †''Mesodma pygmaea, M. pygmaea'' Sloan, 1987
***** Species †''Mesodma formosa, M. formosa'' (Marsh, 1889) [Halodon formosus Marsh, 1889]
***** Species †''Mesodma primaeva, M. primaeva'' (Lambe, 1902)
***** Species †''Mesodma thompsoni, M. thompsoni'' Clemens, 1964
**** Genus ''Ectypodus'' Matthew & Cranger, 1921 [Charlesmooria Kühne, 1969 ]
***** Species †''Ectypodus aphronorus, E. aphronorus'' Sloan, 1981
***** Species? †''Ectypodus childei, E. childei'' Kühne, 1969
***** Species? †''Ectypodus elaphus, E. elaphus'' Scott, 2005
***** Species? †''Ectypodus lovei, E. lovei'' (Sloan, 1966) Krishtlaka & Black, 1975
***** Species †''Ectypodus musculus, E. musculus'' Matthew & Granger, 1921
***** Species †''Ectypodus powelli, E. powelli'' Jepsen, 1940
***** Species? †''Ectypodus simpsoni, E. simpsoni'' Jepsen, 1930
***** Species †''Ectypodus szalayi, E. szalayi'' Sloan, 1981
***** Species †''Ectypodus tardus, E. tardus'' Jepsen, 1930
**** Genus †''Mimetodon'' Jepsen, 1940
***** Species †''Mimetodon krausei, M. krausei'' Sloan, 1981
***** Species †''Mimetodon nanophus, M. nanophus'' Holtzman, 1978 [''Neoplagiaulax nanophus'' Holtzman, 1978]
***** Species †''Mimetodon siberlingi, M. siberlingi''(Simpson, 1935) Schiebout, 1974
***** Species †''Mimetodon churchilli, M. churchilli'' Jepsen, 1940
**** Genus †''Neoplagiaulax'' Lemoine, 1882
***** Species †''Neoplagiaulax annae, N. annae'' Vianey-Liaud, 1986
***** Species? †''Neoplagiaulax burgessi, N. burgessi'' Archibald, 1982
***** Species †''Neoplagiaulax cimolodontoides, N. cimolodontoides'' Scott, 2005
***** Species †''Neoplagiaulax copei, N. copei'' Lemoine, 1885
***** Species †''Neoplagiaulax donaldorum, N. donaldorum'' Scott & Krause, 2006
***** Species †''Neoplagiaulax eocaenus, N. eocaenus'' Lemoine, 1880
***** Species †''Neoplagiaulax grangeri, N. grangeri'' Simpson, 1935
***** Species †''Neoplagiaulax hazeni, N. hazeni'' Jepsen, 1940
***** Species †''Neoplagiaulax hunteri, N. hunteri'' Krishtalka, 1973
***** Species †''Neoplagiaulax jepi, N. jepi'' Sloan, 1987
***** Species †''Neoplagiaulax kremnus, N. kremnus'' Johnston & Fox, 1984
***** Species †''Neoplagiaulax macintyrei, N. macintyrei'' Slaon, 1981
***** Species †''Neoplagiaulax macrotomeus, N. macrotomeus'' Wilson, 1956
***** Species †''Neoplagiaulax mckennai, N. mckennai'' Sloan, 1987
***** Species †''Neoplagiaulax nelsoni, N. nelsoni'' Sloan, 1987
***** Species †''Neoplagiaulax nicolai, N. nicolai'' Vianey-Liaud, 1986
***** Species †''Neoplagiaulax paskapooensis, N. paskapooensis'' Scott, 2005
***** Species? †''Neoplagiaulax serrator, N. serrator'' Scott, 2005
***** Species †''Neoplagiaulax sylvani, N. sylvani'' Vianey-Liaud, 1986
**** Genus †''Parectypodus'' Jepsen, 1930
***** Species †''Parectypodus armstrongi, P. armstrongi'' Johnston & Fox, 1984
***** Species? †''Parectypodus corystes, P. corystes'' Scott, 2003
***** Species? †''Parectypodus foxi, P. foxi'' Storer, 1991
***** Species †''Parectypodus laytoni, P. laytoni'' Jepsen, 1940
***** Species †''Parectypodus lunatus, P. lunatus'' Krause, 1982 [''P. childei'' Kühne, 1969]
***** Species †''Parectypodus simpsoni, P. simpsoni'' Jepsen, 1940
***** Species †''Parectypodus sinclairi, P. sinclairi'' Simpson, 1935
***** Species †''Parectypodus sloani, P. sloani'' Schiebout, 1974
***** Species †''Parectypodus trovessartianus, P. trovessartianus'' Cope, 1882 [''P. trouessarti''; ''Ptilodus''; ''Mimetodon''; ''Neoplagiaulax'']
***** Species †''Parectypodus sylviae, P. sylviae'' Rigsby, 1980 [Ectypodus sylviae Rigby, 1980]
***** Species? †''Parectypodus vanvaleni, P. vanvaleni'' Sloan, 1981
**** Genus †''Cernaysia'' Vianey-Liaud, 1986
***** Species †''Cernaysia manueli, C. manueli'' Vianey-Liaud, 1986
***** Species †''Cernaysia davidi, C. davidi'' Vianey-Liaud, 1986
**** Genus †''Krauseia'' Vianey-Liaud, 1986
***** Species †''Krauseia clemensi, K. clemensi'' Sloan, 1981 [''Parectypodus clemensi'' Sloan, 1981]
**** Genus †''Xyronomys''Rigby, 1980
***** Species †''Xyronomys swainae, X. swainae'' Rigby, 1980 [Xironomys (sic); ?Eucosmodontidae]
**** Genus †''Xanclomys'' Rigby, 1980
***** Species †''Xanclomys mcgrewi, X. mcgrewi''Rigby, 1980
**** Genus †''Mesodmops'' Tong & Wang, 1994
***** Species †''Mesodmops dawsonae, M. dawsonae'' Tong & Wang, 1994
*** Family †Ptilodontidae Cope, 1887 [Ptilodontidae: Ptilodontinae Cope, 1887 sensu McKenna & Bell, 1997]
**** Genus †''Kimbetohia'' Simpson, 1936
***** Species †''Kimbetohia cambi, 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? †''Ptilodus fractus, P. fractus''
***** Species †''Ptilodus kummae, P. kummae'' Krause, 1977
***** Species †''Ptilodus gnomus, P. gnomus'' Scott, Fox & Youzwyshyn, 2002 [cf. ''Ectypodus hazeni'' (Jepsen, 1940) Gazin, 1956]
***** Species †''Ptilodus mediaevus, P. mediaevus'' Cope, 1881 [''Ptilodus plicatus'' (Cope, 1884); ''Chirox plicatus'' Cope, 1884 ''P. ferronensis'' Gazin, 1941]
***** Species †''Ptilodus montanus, P. montanus'' Douglass, 1908 [''P. gracilis'' Gidley, 1909; ''P. admiralis'' Hay, 1930]
***** Species †''Ptilodus tsosiensis, P. tsosiensis'' Sloan, 1981
***** Species †''Ptilodus wyomingensis, P. wyomingensis'' Jepsen, 1940
**** Genus †''Baiotomeus'' Krause, 1987
***** Species †''Baiotomeus douglassi, B. douglassi'' Simpson, 1935 [''Ptilodus''; ''Mimetodon''; ''Neoplagiaulax'']
***** Species †''Baiotomeus lamberti, B. lamberti'' Krause, 1987
***** Species †''Baiotomeus russelli, B. russelli'' Scott, Fox & Youzwyshyn, 2002
***** Species †''Baiotomeus rhothonion, B. rhothonion'' Scott, 2003
**** Genus †''Prochetodon'' Jepsen, 1940
***** Species †''Prochetodon cavus, P. cavus'' Jespen, 1940
***** Species †''Prochetodon foxi, P. foxi'' Krause, 1987
***** Species †''Prochetodon taxus, P. taxus'' Krause, 1987
***** Species? †''Prochetodon speirsae, P. speirsae'' Scott, 2004
** Superfamily † Taeniolabidoidea Granger & Simpson, 1929 sensu Kielan-Jaworowska & Hurum, 2001
*** Genus †''Prionessus'' Matthew & Granger, 1925
**** Species †''Prionessus lucifer, P. lucifer'' Matthew & Granger, 1925
*** Family †Lambdopsalidae
**** Genus †''Lambdopsalis'' Chow & Qi, 1978
***** Species †''Lambdopsalis bulla, L. bulla'' Chow & Qi, 1978
**** Genus †''Sphenopsalis'' Matthew, Granger & Simpson, 1928
***** Species †''Sphenopsalis nobilis, S. nobilis'' Matthew, Granger & Simpson, 1928
*** Family †Taeniolabididae Granger & Simpson, 1929
**** Genus †''Taeniolabis'' Cope, 1882
***** Species †''Taeniolabis lamberti, T. lamberti'' Simmons, 1987
***** Species †''Taeniolabis taoensis, T. taoensis'' Cope, 1882
**** Genus †''Kimbetopsalis''
***** Species †''Kimbetopsalis simmonsae, K. simmonsae''
** Superfamily †Djadochtatherioidea Kielan-Jaworowska & Hurum, 1997 sensu Kielan-Jaworowska & Hurum, 2001[Djadochtatheria Kielan-Jaworowska & Hurum, 1997]
*** Genus? †''Bulganbaatar'' Kielan-Jaworowska, 1974
**** Species? †''Bulganbaatar nemegtbaataroides, B. nemegtbaataroides'' Kielan-Jaworowska, 1974
*** Genus †''Nemegtbaatar'' Kielan-Jaworowska, 1974
**** Species? †''Nemegtbaatar gobiensis, N. gobiensis'' Kielan-Jaworowska, 1974
*** Family †Chulsanbaataridae Kielan-Jaworowska, 1974
**** Genus †''Chulsanbaatar'' Kielan-Jaworowska, 1974
***** Species †''Chulsanbaatar vulgaris, C. vulgaris'' Kielan-Jaworowska, 1974
*** Family †Sloanbaataridae Kielan-Jaworowska, 1974
**** Genus †''Kamptobaatar'' Kielan-Jaworowska, 1970
***** Species? †''Kamptobaatar kuczynskii, K. kuczynskii'' Kielan-Jaworowska, 1970
**** Genus †''Nessovbaatar'' Kielan-Jaworowska & Hurum, 1997
***** Species †''Nessovbaatar multicostatus, N. multicostatus'' Kielan-Jaworowska & Hurum, 1997
**** Genus †''Sloanbaatar'' Kielan-Jaworowska, 1974
***** Species †''Sloanbaatar mirabilis, S. mirabilis'' Kielan-Jaworowska, 1974 [Sloanbaatarinae]
*** Family †Djadochtatheriidae Kielan-Jaworowska $ Hurum, 1997
**** Genus †''Djadochtatherium'' Simpson, 1925
***** Species †''Djadochtatherium matthewi, D. matthewi'' Simpson, 1925[''Catopsalis matthewi'' Simpson, 1925]
**** Genus †''Catopsbaatar'' Kielan-Jaworowska, 1974
***** Species †''Catopsbaatar catopsaloides, C. catopsaloides'' (Kielan-Jaworowska, 1974) Kielan-Jaworowska, 1994 [''Djadochtatherium catopsaloides'' Kielan-Jaworowska, 1974]
**** Genus †''Tombaatar'' Kielan-Jaworowska, 1974
***** Species †''Tombaatar sabuli, T. sabuli'' Rougier, Novacek & Dashzeveg, 1997
**** Genus †''Kryptobaatar'' Kielan-Jaworowska, 1970 [''Gobibaatar'' Kielan-Jaworowska, 1970, ''Tugrigbaatar'' Kielan-Jaworowska & Dashzeveg, 1978]
***** Species †''Kryptobaatar saichanensis, K. saichanensis'' Kielan-Jaworowska & Dashzeveg, 1978 [''Tugrigbaatar saichaenensis'' Kielan-Jaworowska & Dashzeveg, 1978??]
***** Species †''Kryptobaatar dashzevegi, K. dashzevegi'' Kielan-Jaworowska, 1970
***** Species †''Kryptobaatar mandahuensis, K. mandahuensis'' Smith, Guo & Sun, 2001
***** Species †''Kryptobaatar gobiensis, K. gobiensis'' Kielan-Jaworowska, 1970 [''Gobibaatar parvus'' Kielan-Jaworowska, 1970 ]

Phylogeny

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. Traditionally, the extinction of multituberculates has been linked to the rise of rodents (and, to a lesser degree, earlier placental competitors like Hyopsodontidae, hyopsodonts and Plesiadapiformes), which supposedly Competitive exclusion principle, competitively excluded multituberculates from most mammalian faunas.

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 Miacidae, 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.

References

Sources

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{{Taxonbar, from=Q131181

Multituberculates,
Prehistoric animal orders
Prehistoric mammals
Mammal orders
Oligocene extinctions
Kimmeridgian first appearances
Taxa named by Edward Drinker Cope
Fossil taxa described in 1884
Tertiary extinctions of vertebrate taxa