Dietary ecology and niche differentiation of Pliocene-Pleistocene papionins from the Turkana Basin inferred from buccal dental microwear texture analysis and machine-learning approaches

Reconstructing the dietary ecology of fossil primates is essential for understanding how Pliocene–Pleistocene climatic reorganization shaped African ecosystems. During this interval, increasing aridity and climatic variability transformed habitats across eastern Africa, promoting ecological diversification among mammalian lineages. Papionins were key components of these faunas, yet their ecological differentiation remains incompletely resolved. Here, we investigate the dietary regimes of extinct papionins from the Turkana Basin using three-dimensional dental microwear texture analysis (DMTA) of buccal enamel surfaces combined with supervised machine-learning approaches. We analyzed buccal surface textures from fossil specimens of Parapapio ado , Parapapio lothagamensis , Theropithecus oswaldi , Cercopithecoides williamsi and Parapapio sp., applying ISO 25178, ISO 12781, Furrow, and SSFA parameters. After rigorous pre-processing and feature selection, Linear Discriminant Analysis and regularized multinomial logistic regression were used to assess taxonomic separability and identify key microtexture drivers. Cercopithecoides williamsi is characterized by highly distinctive buccal microtexture (notably deep furrows and elevated surface complexity), whereas Theropithecus oswaldi occupies the opposite end of the discriminant space, reflecting contrasting abrasive texture signatures. Parapapio lothagamensis forms a discrete cluster as the oldest taxon in the sample, clearly separated from Parapapio ado and other Parapapio , indicating early ecological divergence within the lineage. These findings demonstrate that buccal DMTA, integrated with machine-learning frameworks, provides a robust tool for resolving ecological differentiation in fossil primates and supports niche partitioning among Pliocene–Pleistocene papionins in the Turkana Basin during a period of major environmental change.