Functional and Character Disparity Are Decoupled in Turtle Mandibles

Area of Science:

• Evolutionary biology
• Comparative anatomy
• Biomechanics

Background:

• Turtles exhibit significant mandibular shape variation, suggesting adaptations to varied diets and feeding strategies.
• Understanding the relationship between morphology, function, and ecology is crucial for evolutionary studies.

Purpose of the Study:

• To compare functional and character disparity in turtle mandibles.
• To investigate the decoupling of functional and morphological evolution.
• To explore patterns of mandibular biomechanics and their ecological correlations.

Main Methods:

• Biomechanical proxies were used to measure functional disparity.
• Discrete morphological characters were analyzed for character disparity.
• Comparisons were made across different turtle clades and ecological groups.

Main Results:

• Functional and character disparities are decoupled across turtle clades and ecological groups.
• Dietary specialists exhibit greater functional disparity than generalists.
• Convergent evolution of feeding types occurs through different biomechanical configurations.
• Turtles maintain high force transmission at the anterior jaw, potentially for high bite forces in small heads.

Conclusions:

• Mandibular evolution in turtles shows complex patterns where function and morphology do not always evolve in concert.
• Dietary specialization drives functional disparity, while generalist diets contribute to character disparity.
• Biomechanical analyses reveal unique adaptations in turtle jaw mechanics, possibly linked to size constraints.