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December 2016
Vol.40-2
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Print ISSN: 0031-0247
Online ISSN: 2274-0333
Frequency: biannual

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L'occlusion dentaire chez Peradectes, Amphiperatherium et Peratherium, Marsupiaux du tertiaire d'Europe.
Jean-Yves Crochet
Keywords: Didelphidae; Eocene; Mastication; Oligocene; Wear facets
 
  Abstract

    The general principles guiding the study of wear facets which develop during mastication in mammals possessing tribosphenic molars are named. The application of this method of study to the molars of European Tertiary Didelphidae shows that the lineage of this family as represented by the species Peratherium cuvieri (Upper Eocene), P. elegans (Lower-middle Oligocene) and P. antiquum (Upper Oligocene) has propessively evolved toward a more carnivorous diet. 


  Article infos

Published in Vol. 9, Ext (1980)

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Functional aspects of the evolution of rodent molars
Percy M. Butler
Keywords: Chewing; Muridae; Rodents; Wear facets
 
  Abstract

    The wear facets of primitive rodents can be homologized with those of primitive primates and ungulates. As in primates, the jaw movement was ectental, with an increased anterior component in the lingual phase (phase ll). The buccal phase (phase I) in rodents approaches the horizontal and it tends to be reduced in importance in comparison with the lingual phase. ln more advanced rodents the efficiency of grinding is increased by the development of additional cutting edges of enamel (e.g. enlargement of hypocone, development of mesoloph and lingual sinus). The buccal phase movement becomes lined up with the lingual phase movement to form a single oblique chewing stroke,resulting in planation of the crown. As the stroke becomes more longitudinal (propalinal) the enamel edges become more transverse. In Muridae propalinal chewing evolved before the loss of cusps, facets were reorientated and additional cusps developed. 


  Article infos

Published in Vol. 9, Ext (1980)

PDF