Peculiar ToothHomologies of the Greater Bamboo Lemur (Prolemur = Hapalemur simus) When is a Paracone Not a Paracone?

Among living primates, bamboo lemurs provide a rare case of adaptation to feeding on fibrous vegetation. Bamboo makes up a significant portion of the diet of all three living species, Hapalemur griseus, H. aureus, and H. simus (now also known as Prolemur simus, Groves, 2001). The latter, the greater bamboo lemur, has perhaps the most monotonous plant diet of all primates. Long term studies on wild greater bamboo lemurs (Tan, 1999) have shown that 95% of its diet is composed of one species of bamboo (Cathyiostachyum madagascariensis). H. simus is also the only species that routinely breaks open and eats the culms (the bamboo’s trunk) of mature bamboo. Even the remaining portion of the diet is made mostly of other bamboo species, with fruit and other foods (mostly soil and mushrooms) making 2% of the diet. Bamboos, which are grasses belonging to the family Poaceae, are highly fibrous. Bamboo culms contain close to 50% cellulose with the remaining material made mostly of lignin and polyose (hemicellulose) (Fengel and Shao, 1984). Additionally, bamboo contains silica bodies (or phytoliths). Taken together, these factors make bamboo a challenging food to consume and digest. It is then perhaps to be expected that the challenge of bamboo feeding should be reflected in the dentition of bamboo lemurs. Indeed, H. O. Forbes in the Allen’s Naturalist’s Library (1894) described the Hapalemur dentition to be ‘‘peculiar and characteristic’’. While several ‘‘peculiarities’’ have been documented in the bamboo lemur dentition (Tattersall, 1982), in this paper we will focus on one, namely the molarization of premolars.