Functional morphology of the douc langur (Pygathrix spp.) scapula

Area of Science:

• Primate Paleontology
• Comparative Anatomy
• Locomotor Biomechanics

Background:

• Most colobine monkeys are arboreal quadrupeds.
• Douc langurs (Pygathrix spp.) display suspensory behaviors, unlike typical colobines.
• Scapular morphology is linked to primate arboreal locomotion.

Purpose of the Study:

• To investigate if douc langur scapular shape resembles obligate brachiators or quadrupeds.
• To analyze the relationship between scapular morphology and locomotor behavior in primates.

Main Methods:

• Recorded 3D landmark data on 100 nonhuman primate specimens across 15 species.
• Utilized 3D digitizing, Procrustes analysis, and Principal Component Analysis (PCA).
• Performed Procrustes ANOVA and phylogenetically controlled ANOVA to test for shape differences.

Main Results:

• Pygathrix scapular morphology significantly differs from both arboreal quadrupeds and hylobatid brachiators (p < 0.01).
• Douc langurs share features with both groups but possess a unique medially placed superior angle.
• Morphological differences suggest specialized adaptations for suspensory locomotion.

Conclusions:

• Douc langur scapular shape is distinct, reflecting unique locomotor behaviors.
• These findings can aid in inferring suspensory locomotion in the primate fossil record.
• The study highlights the importance of detailed morphological analysis in understanding primate evolution.