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Tooth enamel of the cave bear (Ursus spelaeus) and the relationship between diet and enamel structures
Wighart von Koenigswald
Annales Zoologici Fennici
Vol. 28, No. 3/4, Björn Kurtén — a memorial volume (1991), pp. 217-227
Published by: Finnish Zoological and Botanical Publishing Board
Stable URL: http://www.jstor.org/stable/23735446
Page Count: 11
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In the enamel of Ursus spelaeus, prisms with incomplete prism sheaths dominate, although prisms with complete prism sheaths are also present. The Schmelzmuster consists of two indistinctly separated layers. Dominant is the inner layer characterized by well developed Hunter-Schreger bands. The outer layer, varying in thickness, is formed by radial enamel. Aprismatic enamel was found in a few areas close to the enamel-dentine junction but occurs more frequently on the outer surface. The crystallites of the interprismatic matrix are parallel to the prisms or form a slight angle (max. 45°). Although Ursus spelaeus preferred a vegetarian diet, its teeth show typical carnivore enamel and have no similarities with herbivore enamel. In many herbivores, crystallites of the IPM are oriented at wide angles (about 90°) to the prisms and frequently form "inter-row sheets". In comparison to the enamel in carnivores, herbivore enamel is derived and often combined with a secondary occlusal surface. Examples, however, show that both characters are independent. The enamel of Ursus spelaeus demonstrates that a specialization of diet over a short period of time does not have an immediate influence upon enamel structure. Only during longer phases of evolution does selection result in an almost perfect correlation of the Schmelzmuster and stress patterns during mastication.
Annales Zoologici Fennici © 1991 Finnish Zoological and Botanical Publishing Board