Mirusodens, Mao & Li & Hooker & Meng, 2023

Mao, Fangyuan, Li, Zhiheng, Hooker, Jerry J. & Meng, Jin, 2023, A new euharamiyidan, Mirusodens caii (Mammalia: Euharamiyida), from the Jurassic Yanliao Biota and evolution of allotherian mammals, Zoological Journal of the Linnean Society 199 (3), pp. 832-859 : 834

Genus Mirusodens gen. nov.

Type species: Mirusodens caii gen. et sp. nov.

Etymology: Mirus, Latin, amazing, remarkable; dens, tooth; in reference to the remarkable tooth morphology of the new genus.

Diagnosis: Dental formula I1-C0-P3-M2/i1-c0-p1-m2 (upper/ lower incisor, canine, premolar, and molar); differ from other ‘haramiyidans’ in having the following features: the upper incisor considerably larger than molars and having complex and multiple cusps; three upper premolars identified as P2–P4; P4 having complex roots and a heart-shaped crown with numerous cusps that are regularly arranged in curved rows and decrease in size from outer row toward the basin centre; lower ultimate premolar (p4) twice the length of lower molars and having no distal cusp or heel but having serrations along the mesial half of the crown; upper molars with initial cusp Ax and row Ax; lower molars with cusp b1 that projects mesially from the mesiobuccal base of a1.

Remarks: The new genus is dentally distinctive from other ‘haramiyidans’ and other mammaliaforms so that there seems no need to present a differential diagnosis for establishment of the new species. In the description of the dentition, we have a comparison for each set of teeth, which furnishes additional information for species differentiation.