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The expanded mandibular condyle of the Megaladapidae.

Publication ,  Journal Article
Wall, CE
Published in: American journal of physical anthropology
June 1997

The Megaladapidae have a posterior expansion of the articular surface of the mandibular condyle. Several other strepsirhine species exhibit a similar condylar surface. In this study, I propose two behavioral scenarios in which the posterior articular expansion might function: 1) contact with the postglenoid process and resistance to joint stress during browsing, and 2) movement against the postglenoid process during the fast closing and power strokes of mastication, as a consequence of large transverse jaw movements and associated with a strong mandibular symphysis. These models are evaluated through dissection of the TMJ in Lepilemur and from comparative anatomical observations on strepsirhines and ungulates. In Lepilemur the mandibular symphysis is unfused, but compared to the unfused symphyses of other strepsirhines is strengthened by interlocking bony projections (Beecher [1977] Am. J. Phys. Anthropol. 47:325-336). An accessory articular meniscus is found between the posterior articular expansion and the postglenoid process in Lepilemur, suggesting that significant movement occurs in this part of the TMJ. The symphysis is fused in adult specimens of Megaladapis. A posterior articular expansion is common among ungulates, and its presence is associated not with browsing but with symphyseal fusion. This supports the second model and suggests that the posterior articular expansion functions as a movement surface during mastication. Schwartz and Tattersall ([1987] J. Hum. Evol. 16:23-40) cite the posterior articular expansion as a synapomorphy uniting an Adapis-Leptadapis clade with a Megaladapidae-Daubentonia-Indridae clade. The comparative evidence suggests that the posterior articular expansion has evolved convergently in adapines, notharctines, megaladapids, hapalemurids, and indrids as part of a functional complex related to herbivory. However, close morphological similarity of the posterior articular expansion among genera within these strepsirhine subfamilies and families indicates that it is probably a reliable synapomorphy at lower taxonomic levels.

Duke Scholars

Published In

American journal of physical anthropology

DOI

EISSN

1096-8644

ISSN

0002-9483

Publication Date

June 1997

Volume

103

Issue

2

Start / End Page

263 / 276

Related Subject Headings

  • Temporomandibular Joint
  • Strepsirhini
  • Species Specificity
  • Primates
  • Perissodactyla
  • Mastication
  • Mandibular Condyle
  • Diet
  • Artiodactyla
  • Anthropology
 

Citation

APA
Chicago
ICMJE
MLA
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Wall, C. E. (1997). The expanded mandibular condyle of the Megaladapidae. American Journal of Physical Anthropology, 103(2), 263–276. https://doi.org/10.1002/(sici)1096-8644(199706)103:2<263::aid-ajpa9>3.0.co;2-u
Wall, C. E. “The expanded mandibular condyle of the Megaladapidae.American Journal of Physical Anthropology 103, no. 2 (June 1997): 263–76. https://doi.org/10.1002/(sici)1096-8644(199706)103:2<263::aid-ajpa9>3.0.co;2-u.
Wall CE. The expanded mandibular condyle of the Megaladapidae. American journal of physical anthropology. 1997 Jun;103(2):263–76.
Wall, C. E. “The expanded mandibular condyle of the Megaladapidae.American Journal of Physical Anthropology, vol. 103, no. 2, June 1997, pp. 263–76. Epmc, doi:10.1002/(sici)1096-8644(199706)103:2<263::aid-ajpa9>3.0.co;2-u.
Wall CE. The expanded mandibular condyle of the Megaladapidae. American journal of physical anthropology. 1997 Jun;103(2):263–276.
Journal cover image

Published In

American journal of physical anthropology

DOI

EISSN

1096-8644

ISSN

0002-9483

Publication Date

June 1997

Volume

103

Issue

2

Start / End Page

263 / 276

Related Subject Headings

  • Temporomandibular Joint
  • Strepsirhini
  • Species Specificity
  • Primates
  • Perissodactyla
  • Mastication
  • Mandibular Condyle
  • Diet
  • Artiodactyla
  • Anthropology