Temporal variation in soricid dentition: which are first – qualitative or quantitative features?

The current paper offers a protocol for the analytic assessment of the intraspecific variability of dental morphology in shrews. Our approach blends a temporal aspect together with a comparative morphological analysis in terms of a unified morphogenetic concept based on the 'activator-inhibitor cascades model' and 'decreasing heritability model'. We used material from the upper Pleistocene and Holocene fossiliferous deposits of Koridornaya and Sukhaya caves in the Russian Far East and analysed the first upper molars of specimens that were similar in size to the teeth of Crocidura lasiura but differed in some proportions and qualitative features. We analysed the temporal variation of the molar shape against samples of the extant species C. lasiura, Crocidura sibirica and Crocidura shantungensis along with fossil specimens using geometric morphometry based on three-dimensional landmarks and semi-landmark datasets. Our results revealed correspondence of the fossil teeth to intraspecies variation of C. lasiura with a slight increase in the morphospace size. We also found two deviant teeth, which, however, also fell in the range of C. lasiura and were determined as Crocidura cf. C. lasiura. A detailed description of the dental features became possible with the use of the computed microtomography approach. [ABSTRACT FROM AUTHOR]