Multituberculata Cope, 1884

Cifelli, Richard L., Davis, Brian M. & Sames, Benjamin, 2014, Earliest Cretaceous mammals from the western United States, Acta Palaeontologica Polonica 59 (1), pp. 31-52 : 36

Order Multituberculata Cope, 1884

Suborder “Plagiaulacida” Ameghino, 1889

Remarks.— Two “groups” of Multituberculata are conventionally recognized. Hahn and Hahn (2004, 2006) regard the “Plagiaulacida” (the geologically older of the two, with assigned taxa ranging from the Middle Jurassic to Albian– Cenomanian) as a monophyletic group. However, “plagiaulacidans” are generally characterized by plesiomorphies and are often represented by isolated teeth; hence, diagnosis on the basis of synapomorphies is problematic. We conservatively follow the usage of Kielan-Jaworowska et al. (2004) in regarding the “Plagiaulacida” as a paraphyletic grade, pending a detailed phylogenetic analysis. A second group of multituberculates, the Cimolodonta (Albian–Cenomanian to Oligocene), are generally conceived as monophyletic ( Simmons 1993; Kielan-Jaworowska and Hurum 2001; Weil and Krause 2008), though there is not universal agreement on this point (e.g., Hahn and Hahn 1999; Fox 2005). The primary distinctions between “plagiaulacidans” and cimolodontans lie in the incisors and premolar series (e.g., Clemens and Kielan-Jaworowska 1979), but molar characteristics have also proven useful in assessing relationships of taxa known by isolated teeth (e.g., Eaton and Cifelli 2001; Hahn and Hahn 2004; Cifelli et al. 2013). Among the “Plagiaulacida”, Kielan-Jaworowska and Hurum (2001; see also Kielan-Jaworowska et al. 2004) recognize three informal groupings: the allodontid ( Allodontidae Marsh, 1889 and Zofiabaataridae Bakker, 1992 , plus Glirodon Engelmann and Callison, 1999 ), paulchoffatiid ( Paulchoffatiidae Hahn, 1969 ; Hahnodontidae Sigogneau-Russell, 1991b ; and Pinheirodontidae Hahn and Hahn, 1999 ), and plagiaulacid ( Plagiaulacidae Gill, 1872 ; Eobaataridae Kielan-Jaworowska, Dashzeveg, and Trofimov, 1987 ; and Albionbaataridae Kielan-Jaworowska and Ensom, 1992 ; plus Janumys Eaton and Cifelli, 2001 ) “lines”, with the Arginbaataridae Hahn and Hahn, 1983 considered incertae sedis. These “lines” were formalized (with some changes in content) as superfamilies by Hahn and Hahn (2004), who also placed the Arginbaataridae in their own superfamily.

We recognize two new multituberculates, each represented by an isolated molar, from the Lakota Formation. Available data suggest that both are “plagiaulacidans”, each referable to a different superfamily, following the taxonomic arrangement of Hahn and Hahn (2004). Authorship for superfamilies listed below reflects Article 36.1 of the International Code of Zoological Nomenclature ( ICZN 1999).