They ranged from the Middle Jurassic Period to the early Late Cretaceous of the northern hemisphere.

[1] Kielan-Jaworowska and Hurum (2001) divides “Plagiaulacida” into three informal lineages, the paulchoffatiids, the plagiaulicids, and the allodontids.

The Allodontid line contains: The family Allodontidae is known from two genera from the Upper Jurassic Morrison Formation of North America.

Family Plagiaulacidae is known from the Upper Jurassic (North America) to Lower Cretaceous (Europe), being represented by Plagiaulax, Bolodon, and Morrisonodon.

Family Albionbaataridae is known from the Upper Jurassic to Lower Cretaceous of Europe and Asia, (China – undescribed, 2001).

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.