Print ISSN: 0031-0247
Online ISSN: 2274-0333
A pangolin from the French Quercy phosphorites
Abstract book of the 18th Conference of the EAVP
FOSSIL SELACHIANS FROM THE BANDAH FORMATION
A new stem hystricognathous rodent from the Eocene of Tunisia
Physogaleus hemmooriensis, a new shark species from the early to middle Miocene of the north sea basin
Functional aspects of the evolution of rodent molarsChewing; Muridae; Rodents; Wear facets
Cite this article: Butler P. M., 1980. Functional aspects of the evolution of rodent molars. Palaeovertebrata 9 (ext): 249-262.
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)