Abstract
Sulcal patterns were determined from endocasts of fossilTheropithecus (T. oswaldi andT. darti) and compared to the sulcal pattern of extant geladas (T. gelada). A comparison of the configurations of central and arcuate sulci suggests that the cortical motor face representation is relatively enlarged in extantTheropithecus, whereas the cortical motor and sensory face representations were enlarged inT. oswaldi. A relatively expanded sensory and/or motor cortical face representation may be related to masticatory (e.g., “seed-eating”) and gestural (e.g., “lipflip”) functions. SinceT. oswaidi is more derived (expanded) in sensory face representation thanT. gelada, it seems unlikely that it was a direct ancestor of modern geladas. Rather, the two groups were separate by 1.8 million years ago and may have had a most recent common ancestor similar toT. darti from the Hadar Formation of Ethiopia between 2 and 3 million years ago.
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Falk, D. Sulcal patterns of fossilTheropithecus baboons: Phylogenetic and functional implications. Int J Primatol 2, 57–69 (1981). https://doi.org/10.1007/BF02692300
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DOI: https://doi.org/10.1007/BF02692300