Wear reconstruction of the teeth of Yindirtemys deflexus (Ctenodactylidae, Rodentia) and evolution of its dental pattern

Abstract

The dental pattern of Yindirtemys deflexus from Mongolia has been analysed using a Micro-CT scanner. This ctenodactylid exhibits a peculiar dental pattern, characterised by a mesodont dentition with some degree of selenodonty, an intricate enamel folding and elevated connections between cusps. Furthermore, the wear sequence in the upper tooth row shows very worn M1 even before other teeth emerge. The descriptive parameters used in the analyses (Area, Perimeter and structural density) allowed us to determine the relative wear stage in the different dental elements. The study reveals for Yindirtemys deflexus a wear pattern typical of mesodont teeth in which the maximum perimeter of the enamel is relatively constant over a large part of the crown height, and the Structural density decreases progressively until the senescence of the tooth. This peculiar dental morphology and eruption sequence of Y. deflexus is interpreted as the result of the evolution towards a relatively more durable dentition caused by the adaptation to more arid environments.