International Journal of Primatology

, Volume 4, Issue 1, pp 99–112 | Cite as

Evolution of the mandibular symphysis in Notharctinae (Adapidae, Primates)

  • Robert M. Beecher


The Eocene Notharctinae provide a record of increasing fusion of the mandibular symphysis. The two sympatric genera,Notharctus andSmilodectes, differed through time in two respects.Notharctus increased in body size and evolved a partially fused mandibular symphysis.Smilodectes changed little in body size and retained an unfused symphysis. Similarities in molar morphology between these two genera and extant leaf-eating mammals suggest thatNotharctus andSmilodectes were specialized for folivory, a dietary regime correlated with partial symphyseal fusion in many extant mammals. It is concluded that the presence and the extant of symphyseal fusion is a function of body size, diet, and jaw mechanics, complicated by lineagespecific factors that vary among higher mammalian taxa.

Key words

mandibular symphysis fossils Notharctinae 


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Copyright information

© Plenum Publishing Corporation 1983

Authors and Affiliations

  • Robert M. Beecher
    • 1
  1. 1.Department of AnatomyWright State UniversityDayton

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