The Multituberculata are the only major branch of mammals to have become completely extinct, with no living descendants. Rodent-like, they first appeared in the Middle Jurassic, and became extinct in the early Oligocene. Orders Subclass Monotremata Monotremata Subclass Marsupialia Didelphimorphia Paucituberculata Microbiotheria Dasyuromorphia Peramelemorphia Notoryctemorphia Diprotodontia Subclass Placentalia Xenarthra Dermoptera Desmostylia Scandentia Primates Rodentia Lagomorpha Insectivora Chiroptera Pholidota Carnivora Perissodactyla Artiodactyla Cetacea Afrosoricida Macroscelidea Tubulidentata Hyracoidea Proboscidea Sirenia The mammals are the class of vertebrate animals primarily characterized by the presence of mammary... The Jurassic period is a major unit of the geologic timescale that extends from about 195 million years BP at the end of the Triassic to 135 million years BP at the beginning of the Cretaceous. ... The Oligocene epoch is a geologic period of time that extends from about 33. ...

They are named for their teeth, which had many cusps (tubercles) arranged in rows, hence multituberculates.

About 80 genera of multituberculata are known, including Lambdopsalis, Ptilodus and Meniscoessus. See genus (mathematics) for the use of the term in mathematics. ... Species    Ref. ... Species Ptilodus is a genus of mammals from the extinct order of Multituberculata, and lived during the Paleocene in North America. ... Species                      Ref. ...

Groups within Multituberculata

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. Families   Allodontidae   Zofiabaataridae   Paulchoffatiidae   Hahnodontidae   Pinheirodontidae   Plagiaulacidae   Albionbaataridae   Eobaataridae Plagiaulacida is a group of extinct mammals. ... Genera   Arginbaatar Ref. ...

"Plagiaulacida" is paraphyletic; it is an informal suborder which doesn't satisfy the cladistic criterion of consisting of an ancestor and all of its descendants. Its members are the more basal multis. 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. Greek clados = branch) or phylogenetic systematics is a branch of biology that determines the evolutionary relationships of living things based on derived similarities. ... The Cretaceous period is one of the major divisions of the geologic timescale, reaching from the end of the Jurassic period (about 135 mya) to the beginning of the Paleocene epoch of the Tertiary period (65 mya). ...

Cimolodonta is apparently a natural (monophyletic) suborder. This includes the more derived Multituberculata, which have been identified from the Lower Cretaceous to the Eocene. Recognized are the superfamilies Djadochtatherioidea, Taeniolabidoidea, Ptilodontoidea and the Paracimexomys group. Superfamilies   Paracimexomys group   Djadochtatherioidea   Taeniolabidoidea   Ptilodontoidea    Other families   Eucosmodontidae   Microcosmodontidae   Kogaionidae   Cimolomyidae   Boffiidae Ref. ... In phylogenetics, a group is monophyletic (Greek: of one stem) if all organisms in that group are known to have developed from a common ancestral form, and all descendants of that form are included in the group. ... The Eocene epoch (55-37 mya) is a major division of the geologic timescale and the second epoch of the Tertiary period in the Cenozoic era. ... Families   Sloanbaataridae   Djadochtatheriidae   Other genera   Bulganbaatar   Chulsanbaatar   Nemegtbaatar Ref. ... Family   Taeniolabididae   Genera:   Catopsalis   Lambdopsalis   Prionessus   Sphenopsalis   Taeniolabis Taeniolabidoidea is a group of extinct mammals known from North America and Asia. ... Families   Neoplagiaulacidae   Ptilodontidae   Cimolodontidae   Other genus   Neoliotomus Ref. ... Genera   Paracimexomys   Bryceomys   Dakotamys   ?Cimexomys   ??Cedaromys Ref. ...

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. Genera Cimolomys Buginbaatar (?) Essonodon Meniscoessus Cimolomyidae is a family of fossil mammal within the extinct order Multituberculata. ... Species    Ref. ... Genera   Eucosmodon   Clemensodon   Stygimys Ref. ... Genera   Kogaionon   Barbatodon   Hainina Kogaionidae is a family of fossil mammals within the extinct order Multituberculata. ... Genera   Microcosmodon   Acheronodon   Pentacosmodon Ref. ... Species    Uzbekbaatar is a genus of extinct mammal from the Upper Cretaceous of Uzbekistan. ... Species    Ref. ...

Geographic distribution

With the possible exception of some poorly preserved South American material, multis are only known from the northern hemisphere. A southern grouping, Gondwanatheria, has in the past been referred to the order, though this placement currently has little support. Genera Family Sudamericidae    Gondwanatherium    Lavanify    Sudamerica Family Ferugliotheriidae    Ferugliotherium Gondwanatheria is an extinct suborder of mammals that lived during the Upper Cretaceous through the Eocene, in the southern hemisphere including Antarctica. ...

References

• Kielan-Jaworowska Z. and Hurum J.H. (2001), "Phylogeny and Systematics of multituberculate mammals". Paleontology 44, p.389-429.
• Most of this information has been derived from Multituberculata (Cope 1884) (http://home.arcor.de/ktdykes/multis.htm)