Unification of Criteria for Distinguishing Morphotypes of Cheek Teeth in Lemmings (Lemmini, Arvicolinae, Rodentia)

Abstract

This paper summarizes the data on morphotype dental patterns in recent lemmings (Lemmini) and their earliest presumed ancestors based on analysis of both the existing literature and zoological collections. The criteria for distinguishing the morphotypes are unified, and four metrics are proposed for assessment: (1) the occlusal surface complexity, (2) the regularity of enamel cutting edges, (3) the asymmetry of the lingual and buccal prisms, and (4) the degree of cement deposition in reentrant angles. A catalogue of basic, reserve, and rare morphotypes has been created for Lemmus sibiricus and Myopus schisticolor. The approach developed here is recommended for further research into the spatial, temporal, and ontogenetic variation in Lemmini, based on their dental characters.