Article: Tiny plagiaulacoid multituberculate mammals from the Purbeck Limestone Formation of Dorset, England

Albionbaatar gen. nov., assigned to the Albionbaataridae fam. nov., in the Plagiaulacoidea, described upon the basis of A. denisae sp. nov. based on minute (about 1-5 mm long) upper premolars (P5) an three anterior upper premolars (0-5-0-9 mm long), all from the Purbeck Limestone Formation of southen England. Two incomplete lower premolars (p4), each found in a sample yielding an upper premolar < Albionbaatar, are described as Plagiaulacoidea, fam., gen. et sp. indet, and we speculate whether they may I counterparts of Albionbaatar. Albionbaatar differs from known multituberculates in having upper premolar with greater numbers of very small cusps, arranged in three longitudinal rows, and P5 with extensive lingual slope covered by transverse ridges. The oblique lingual slope on P5, characteristic of Albionbaatar, occurs in previously known plagiaulacoids, where there are no ridges. The structure of Albionbaatar shows that the correlation between tooth size and number of cusps characteristic for the Cimolodonta (at least for the Taeniolabidoidea) may not hold for all the Plagiaulacoidea.