Plagiaulacida is a group of extinct mammals. Multituberculates were among the most common mammals of the Mesozoic, "the age of the dinosaurs". Plagiaulacids, an informal suborder, are the most basal of this order, and ranged from the Middle Jurassic Period to the Lower Cretaceous Period of the northern hemisphere.
Kielan-Jaworowska and Hurum (2001) divides “Plagiaulacida” into three informal lineages, each of which seems to represent a natural group (an ancestor and all its descendants). However, a firmer conclusion must await further evidence.
Both allodontids and paulchoffatiids (below) were among the most basal of the plagiaulacids. The Allodontid line contains:
The family Zofiabaataridae contains a single genus, Zofiabaatar and is also from the Morrison Formation. The affinities of a further Morrison Formation genus, Glirodon, are unclear, but it’s also within the Allodontid line.
Some remains from the Middle Jurassic of England might belong within this group. Representatives are best known from the Upper Jurassic, (especially from Guimarota, Portugal), though some were still extant during the Lower Cretaceous.
The genera of the family Paulchoffatiidae are divided into two of subfamilies, plus a couple of harder-to-place individuals:
Subfamily Paulchoffatiinae includes Paulchoffatia and its relatives. This taxon contains nine genera.
Subfamily Kuehneodontinae consists solely of the genus Kuehneodon, though there are half-a-dozen named species.
Also referable to the paulchoffatiid line, but not the family itself, are the following:
Family Albionbaataridae is known from the Upper Jurassic to Lower Cretaceous of Europe and Asia, (China – undescribed, 2001). These were shrew-sized Multituberculates, with some similarities to the paulchoffis.
Members of the family Eobaataridae display dental similarities with some of the Paracimexomys group, (Cimolodonta). They are known from the Upper Jurassic to Lower Cretaceous of Europe and Asia, (China – undescribed, 2001).
Sinobaatar was described after the study by Kielan-Jaworowska and Hurum (2001). It might be based on some of the Chinese material they mentioned as undescribed. The Mongolian word ‘baatar’ is frequently employed in the nomenclature of Multituberculates. This reflects the fact that many of the most complete fossils have been recovered from sites in Mongolia, though this more applies to members of the more derived Cimolodonta.
A couple of further genera possibly fit somewhere within “Plagiaulacida”. This has been tentatively proposed for Janumys of the Middle Cretaceous. Its contemporary, Ameribaatar, is of uncertain affinities. Both were first described late in 2001.