Structure and function of platyrrhine caudal vertebrae

Area of Science:

• Comparative anatomy
• Primate evolution
• Functional morphology

Background:

• The prehensile tail, crucial for arboreal locomotion in platyrrhines, has evolved independently multiple times.
• Structural differences underlying prehensile tail function remain poorly understood.
• Previous studies relied on limited distal vertebral measurements.

Purpose of the Study:

• To investigate structural differences in prehensile versus nonprehensile tails.
• To test if caudal vertebrae are adapted for higher stress resistance in prehensile tails.
• To determine if these differences intensify distally.

Main Methods:

• External tail measurements assessing bending/torsion resistance.
• Computed tomography (CT) to analyze vertebral cross-sectional geometry.
• Comparative analysis of prehensile and nonprehensile platyrrhine tails.

Main Results:

• Prehensile tails exhibit longer proximal regions and more developed hemal processes.
• Vertebral structure in prehensile tails shows greater resistance to bending and torsion.
• These structural disparities increase along the distal tail sequence.

Conclusions:

• Prehensile and nonprehensile tails possess distinct structural properties.
• Caudal vertebrae in prehensile tails are specialized for enhanced mechanical stress resistance.
• These findings highlight the evolutionary effectiveness of prehensile tails in arboreal environments.