Enamel microstructure of some fossil and extant murid rodents of India
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概要
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Spatial arrangement of various enamel types (schmelzmuster) present in the incisors and molars of some fossil and extant murid rodents of India was studied from both the functional and phylogenetic points of view. Hunter-schreger bands (HSBs) along with radial enamel (RE) in mice molars have been found to occupy the entire height of the enamel crown (from the base to the top) on the anterior and the posterior portions. These HSBs tend to be horizontal around the base and inclined apically around the top. A clear distinction between the leading and the trailing edges of chewing surfaces based on the difference in the orientation of prisms has been observed in hypsodont murid molars. On the leading edges, the long axes of prisms originating from the enamel-dentine junction tend to be oriented towards the load, whereas those on the trailing edges turn away from the load. The schmelzmuster in molars of Mus, indicate an omnivorous diet, whereas that in Golunda, Millardia, and Bandicota points to adaptation for an abrasive diet. The Indian bandicoot rat (Bandicota) with its large, hypsodont molars has developed horizontally oriented (relative to the occlusal surface) HSBs at the base of the enamel crown. These HSBs have been found in enamel layers oriented both almost parallel and perpendicular to the occlusal surface, an observation that corroborates the presence of horizontal tension at the base of the tooth due to vertical load on the occlusal surface. In the light of the observations made here, a model depicting changes in schmelzmuster in murid rodents through Late Miocene and Plio-Pleistocene times is suggested.
- 日本古生物学会の論文
- 2002-09-30
著者
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Patnaik Pajeev
Centre Of Advanced Study In Geology Panjab University
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Patnaik Rajeev
Centre Of Advanced Study In Geology Panjab University