Student Prize Award Abstract
1999 Oral Paper Honorable Mention
AN EVOLUTIONARY PERSPECTIVE ON DENTAL DEVELOPMENT IN THE SIAMANG
(SYMPALANGUS SYNDACTYLUS) FROM HISTOLOGY AND RADIOGRAPHY
Wendy Dirks Dept. of Anthropology, New York University, 25 Waverly Place,
New York, NY 10003
Dental development correlates well with other aspects of growth and has frequently
been used in studies of ontogeny and life history in primates. This study uses histological
and radiographic data from skeletal material to examine the possible effects of phylogeny on
growth. I compare the timing and sequence of dental development in siamangs (Symphalangus
syndactylus) to available data for other catarrhines of similar body mass as well as the
smaller hylobatid, Hylobates lar. Data on the chronology of dental development were
collected from histological thin sections of the dentitions of three siamangs. Radiographs of
4 additional siamangs and 18 gibbons were examined and scored for stages of development.
The pattern of initiation and completion of crown formation in the siamang was similar to that
reported for Proconsul heseloni, and differed from baboons of similar body mass and H.
lar. Age at eruption of the maxillary first molar in one siamang occurred at 2.38 years,
later than the mean reported for baboons. Differences between gibbon and siamang appear to be
related to development of the canine in the smaller jaws of the gibbon and may indicate the
retention of the primitive pattern in the siamang and phyletic dwarfing in the gibbon.
This research was funded by the Elizabeth S. Watts Fellowship in Nonhuman Primate Growth
and Development and NSF Dissertation Improvement Grant SBR-9700822.