Print ISSN: 0031-0247
Online ISSN: 2274-0333
Révision des Rhombodontidae (Neoselachii Batomorphii) des bassins à phosphate du Maroc
Evolution et extinction des reptiles marins au Mésozoïque
La palichnofaune de vertébrés tétrapodes du permien supérieur du Bassin de Lodève .
Les oiseaux aquatiques (Gaviiformes à Anseriformes) de Saint-Gerand-le-Puy. Révision systématique.
A pangolin from the French Quercy phosphorites
Functional aspects of the evolution of rodent molarsChewing; Muridae; Rodents; Wear facets
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.
Published in Vol. 9, Ext (1980)