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A functional framework for interpreting phalangeal form.
Edwin Dickinson1, Melody W Young1, Nicholas D Flaim1
1Department of Anatomy, New York Institute of Technology College of Osteopathic Medicine, Old Westbury, NY, USA.
Journal of the Royal Society, Interface
|August 15, 2023
Summary
Many tetrapod species evolved unique finger and toe bone structures to enhance gripping strength for specialized locomotion and hunting. This adaptation allows arboreal species to grasp larger branches effectively.
Area of Science:
- Evolutionary biology
- Comparative morphology
- Biomechanics
Background:
- Tetrapod limb phalanx proportions typically follow a proximodistal shortening gradient.
- Some mammal and bird lineages exhibit convergent evolution, shortening proximal phalanges and elongating distal ones.
Purpose of the Study:
- To investigate the functional basis for convergent evolution of phalangeal morphology in tetrapods.
- To test hypotheses explaining why certain lineages deviate from the generalized phalangeal blueprint.
Main Methods:
- Comparative phylogenetic analysis of phalangeal morphology in mammals and birds.
- Bioinspired robotics approach to test functional hypotheses.
- Analysis of trochlear height adaptations in suspensory mammals.
Main Results:
- Shortening proximal phalanges maximizes forces at the proximal interphalangeal joint.
- Elongating distal elements maintains total ray length for grasping large supports.
- Increased trochlear height enhances grip strength in suspensory mammals by increasing flexor muscle moment arms.
Conclusions:
- Convergent evolution of this morphotype maximizes proximal gripping strength in diverse tetrapod lineages.
- This adaptation supports specialized hunting and locomotor behaviors, particularly in arboreal species.
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