Gusev A.E., Tiunov M.P.
Zoologicheskiy zhurnal 2021; 100(1): 104-114
The shape variability of the chewing surface of the third lower premolar (p3) was analyzed in modern members of the Northern Pika (Ochotona hyperborea). Variability of three main features characterizing the tooth shape was revealed: the visual position of the isthmus connecting the anteroconid and the posteroconid, and separately the shapes of both anteroconid and posteroconid. A combinatory matrix showing the distribution of the three morphotypes of the p3 chewing surface was developed based on their distinguishing features. Both the north and the south of the pika’s distribution area are dominated by individuals differing in p3 morphotypes.
