Distribution of Elements in Beaver (Castor fiber) Tooth Enamel as a Sign of Environmental Adaptation: the Special Role of Fe, Co, Mg, and Fluorides (F−)

Abstract

The aim of the study was to investigate the distribution of elements (Ca, Mg, Fe, P, Zn, Na, K, Cu, Cr, Mo, Co, Se) analyzed using inductively coupled plasma optical emission spectrometry (ICP-OES) and fluorides (F⁻) determined potentiometrically using an ion-selective electrode in the enamel of European beaver (Castor fiber) teeth. Material for the study was tooth enamel collected from lower jaws from the skulls of the animals borrowed from museum collections (animals inhabited north-western Poland). The results of our study indicate the important role of F⁻ as an element that can affect the hardness and strength of beaver tooth enamel. Critical to the function of beaver teeth (i.e., shearing and crushing wood) is the presence of elements such as Fe in the central incisor labial aspect (orange layer of the incisor enamel), Mg in the inner side of the incisor enamel, and Co and F⁻ in the enamel of the molars. Thanks to the high content of these elements, the enamel is durable and the teeth are adapted to the nutritional and ecological characteristics of this mammalian species. Our study on the distribution of elements in the enamel of beaver teeth may also be important for the understanding of the enamel mineralization processes, determining how elements change the properties of the materials, and exploring the relationship between the environment and life history of the beaver.