Effect of diet on dental development in four species of catarrhine primates.

In this study, dental development is described in two pairs of closely related catarrhine primate species that differ in their degree of folivory: 1) Hylobates lar and Symphalangus syndactylus, and 2) Papio hamadryas hamadryas and Semnopithecus entellus. Growth increments in histological thin sections are used to reconstruct the chronology of dental development to determine how dental development is accelerated in the more folivorous species of each pair. Although anterior tooth formation appears to be unrelated to diet, both S. syndactylus and S. entellus initiate the slowest-forming molar earlier than the related less-folivorous species, which supports the hypothesis that dental acceleration is related to food processing. S. syndactylus initiates M2 crown formation at an earlier age than H. lar, and S. entellus initiates and completes M3 at an earlier age than P. h. hamadryas. Similar stages of M3 eruption occur earlier in the more folivorous species; however, the sex of the individual may also play a role in creating such differences. Although the age at M3 emergence is close to that reported for the end of body mass growth in lar gibbons, hamadryas baboons, and Hanuman langurs, M3 emergence may not be coupled to body mass growth in siamangs.