Dental Microwear Texture Analysis of the Bornean Orangutans (Pongo pygmaeus) From the Selenka Collection.

Objectives: Characterizing the diet of extant taxa is important not only to determine their ecological niche but also to serve as a reference for dietary and niche inferences in evolutionary studies. Tracking the diets of fossil taxa and their change through time has been increasingly employed to further understand the evolution of primates. In the last decades, several studies using stable isotope analysis, dental topography, or dental microwear analysis have been conducted to reconstruct the paleoecology and diet of fossil pongines. However, paleodietary reconstructions based on the dental microwear of fossil pongines lacked a well-defined and extensive reference dataset of extant Pongo.

Material and methods: To close this gap, we characterized intrapopulation variation in dietary ecology using dental microwear textures of 89 orangutans collected by Emil and Margarethe Selenka on Borneo in 1894.

Results: Our study provides insights into dietary variation in extant Pongo and aims as an important reference dataset in future paleodietary reconstructions. According to climatic records available for the late 19th century, the specimens were not collected during an El Niño event; these events impact fruit resource abundance in Southeast Asia. We found no significant differences in dental microwear textures depending on sex, age, or locality.

Discussion: This suggests that, despite a large number of specimens and localities sampled, sex, age, and locality did not significantly influence the dietary resources consumed at the scale of the population. More detailed individual information-not available for this historical collection-would be necessary to further test these results.