141 - Timing of Deciduous Toothcomb and Third Permanent Molar Eruption in Gummivores

Poster Board Number: 141
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Abstract Body : Gummivory within strepsirrhine primates is associated with robusticity in the toothcomb and, within lorisoids (e.g., galagids), reduction in the upper and lower third molars (M3). We know little, however, about the ontogeny of these dental patterns and the ontogeny of gummivory as a feeding behavior. The present study examined eruption timing of the toothcomb and M3 to test the hypothesis that the toothcomb erupts earlier in gummivorous strepsirrhines and that M3 eruption is delayed. We gathered eruption data from cadavers of two galagids (Galago moholi, a facultative gummivore, and Otolemur crassicaudatus, an obligate gummivore) and three lemurids (Eulemur coronatus, a facultative gummivore, Lemur catta, and Varecia spp., two species who consume no gums). These cadavers ranged in age from fetal to juvenile stages and were obtained opportunistically, from natural deaths in captive populations. Amira software was used to segment teeth and mandibular bone. The two galagids have the earliest eruption of the toothcomb and have fully developed toothcomb roots by one month. Additionally, Galago moholi have fully erupted M3 by three months, but in comparison, a similarly aged O. crassicaudatus has an unerupted and relatively small M3, though degree of mineralization was similar among molars. Moreover, in both G. moholi and O. crassicaudatus the permanent toothcomb has fully developed roots by two and three months, respectively. In contrast, lemurids appear far slower in dental eruption overall, even including some deciduous postcanine teeth. The permanent toothcomb has, as yet, unformed roots even at two months in Eulemur and at 20 months in Varecia rubra. In lemurids, the last permanent molars (M2, M3) are far slower to mineralize crowns, especially in Varecia spp. Certain trends seem related to phylogeny, for example the overall fast rate of dental eruption and crown formation in galagids. Additionally, the influence of body size cannot be discounted in the current sample size. However, the only obligate gummivore, O. crassicaudatus had an underdeveloped M3 compared to G. moholi, supporting one of our hypotheses. A larger sample size is needed for robust hypothesis testing but the present results point to the potential for dental divergence early in ontogeny for an obligate strepsirrhine gummivore.