Scapular Morphology and Forelimb Use during Foraging in Four Sympatric Cercopithecids

Area of Science:

• Primate Paleontology
• Comparative Anatomy
• Behavioral Ecology

Background:

• Primate scapular morphology is often linked to locomotion.
• The relationship between scapular geometry and nonlocomotor behaviors, such as foraging, is less understood.
• Understanding this link can enhance interpretations of the primate fossil record.

Purpose of the Study:

• To investigate the covariation between nonlocomotor forelimb use during foraging and scapular morphology in four cercopithecid species.
• To determine if observed differences in forelimb behavior are reflected in specific scapular features.
• To provide a basis for more informed interpretations of primate skeletal morphology in extinct species.

Main Methods:

• Observational study of four cercopithecid species (Piliocolobus badius, Colobus polykomos, Cercocebus atys, Cercopithecus diana) in Ivory Coast's Tai Forest.
• Recording frequency of five forelimb behaviors during 5-minute feeding bouts.
• Morphological examination of cercopithecid scapulae to identify features related to arm flexion, abduction, and elevation.

Main Results:

• Significant interspecific differences in forelimb use during foraging were observed.
• These behavioral differences correlate with distinct scapular morphologies.
• Piliocolobus badius exhibits greater arm flexion, abduction, and elevation compared to Colobus polykomos, with corresponding differences in scapular features like supraspinous fossa size and orientation.

Conclusions:

• Scapular morphology in cercopithecids is influenced by nonlocomotor behaviors, particularly foraging-related forelimb use.
• The study demonstrates a link between specific feeding behaviors and skeletal adaptations in the scapula.
• This research offers new insights into interpreting primate fossil scapulae, moving beyond solely locomotor-based analyses.