Ng. Jablonski et Rh. Crompton, FEEDING-BEHAVIOR, MASTICATION, AND TOOTH WEAR IN THE WESTERN TARSIER (TARSIUS-BANCANUS), International journal of primatology, 15(1), 1994, pp. 29-59
We assessed feeding and masticatory function in western tarsiers, Tars
ius bancanus, from field study, from videotaped recordings of the feed
ing and chewing behavior of wild-caught animals in temporary captivity
, from dissections of the muscles of mastication, and from scanning el
ectron microscopic (SEM) examination of wear features of the teeth. In
gestion of large items of animal prey is made possible by the animal's
extremely wide gape. Anterior translation of the knob-like mandibular
condyle in the anteroposteriorly elongated mandibular fossa makes pos
sible a gape angle of 60-70-degrees. We observed two means of ingestio
n of grasshopper prey: ingestion by mastication, in which the postcani
ne teeth sever and reduce bites of the food as it is thrust into the m
outh cavity, and repeated gape-shove sequences, during which the tarsi
er pushed grasshoppers of large diameter into the anterior part of its
mouth and attempted to sever a bite with its anterior teeth. Morsels
were successfully severed after three to five such sequences, and redu
ced quickly, with relatively few powerful, crushing chews. The insect
cuticle was not evenly comminuted during mastication. We observed a ma
rked side-to-side grinding component in the normal chewing cycle of T.
bancanus on videotape and confirmed it by SEM. The main jaw adductors
are bulky, long-fibered muscles that can accommodate wide grapes and
still generate, at wide degrees of gape, the high occlusal pressures n
ecessary to fracture thick chitinous exoskeletons of the scarabid beet
les that form a substantial element of the western tarsier's diet.