How mangabey molar form differs under routine vs. fallback hard-object feeding regimes.

Area of Science:

• Primate Paleontology
• Dental Microwear Analysis
• Paleoecology

Background:

• Dietary fallback foods are crucial for primate dental anatomy evolution.
• Thick enamel in grey-cheeked mangabeys (Lophocebus albigena) is linked to fallback hard seed consumption.
• Sooty mangabeys (Cercocebus atys) consume hard foods routinely, also possessing thick enamel, complicating interpretations.

Purpose of the Study:

• To investigate differences in enamel properties beyond thickness between Cercocebus atys and Lophocebus albigena.
• To test the hypothesis that Cercocebus atys molars are more fracture and wear resistant due to routine hard-object feeding.

Main Methods:

• Examined critical fracture loads, nanomechanical properties, and enamel decussation in Cercocebus atys and Lophocebus albigena molars.
• Included molars from Cercopithecus (not a hard-object feeder) for comparative analysis.
• Utilized micro-computed tomography (µCT) for fracture load estimation and scanning electron microscopy (SEM) for enamel structure.

Main Results:

• Cercocebus atys molars showed significantly greater critical fracture loads than Lophocebus albigena and Cercopithecus.
• Nanomechanical properties (elastic modulus, hardness) were higher in Cercocebus atys, especially in outer enamel.
• Cercocebus atys enamel exhibited more complex decussation patterns compared to the other two taxa.

Conclusions:

• Cercocebus atys molars possess enhanced fracture and wear resistance, supporting the hypothesis of adaptation to routine hard-object feeding.
• Differences in enamel properties between the two mangabey species clarify the link between feeding strategies and dental anatomy.
• Findings provide a basis for inferring diet in fossil primates, distinguishing between fallback and routine hard-object consumption.