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The thoracic shape of hominoids
1Department of Biological Anthropology and Anatomy, Duke University Medical Center, Durham, NC 27708, USA ; Institute of Medical and Health Sciences Education, and Department of Anatomy, The University of Hong Kong, Hong Kong.
Anatomy Research International
|May 13, 2014
Summary
Hominoid thoracic shape is larger and broader, particularly in the cranial region, influencing scapular position and respiratory function. This study quanties thoracic dimensions in primates to explain these adaptations.
Area of Science:
- Primate anatomy
- Evolutionary biology
- Biomechanics
Background:
- Broad thorax in hominoids is linked to dorsal scapular position.
- Previous studies suggest a longer dorsoventral diameter in hominoid cranial thoraces.
- Insufficient data exists on thoracic shape to fully explain this relationship.
Purpose of the Study:
- To present data on multilevel cross-sectional shape and volume distribution in primate thoraces.
- To investigate the relationship between thoracic breadth and scapular position in hominoids.
- To explore potential locomotor and respiratory adaptations related to hominoid thoracic morphology.
Main Methods:
- Biplanar radiographs of fluid-preserved primate cadavers were utilized.
- Cross-sectional shape was measured at ten equally spaced decisternal levels.
- Relative volume of nine intervening thoracic segments was quantified.
Main Results:
- Hominoid cranial thoraces are larger and broader than other primates, except at the first two decisternal levels.
- The dorsoventral diameter of the hominoid cranial thorax is longer due to volume increase overcompensating for broadening.
- Thoracic shape variations were observed across different primate groups.
Conclusions:
- The larger and broader cranial thorax in hominoids is a significant locomotor adaptation for enhanced scapular gliding.
- This morphology also serves as a respiratory adaptation, mitigating ventilation-perfusion inequality associated with orthograde posture.
- Thoracic shape is a key factor in understanding hominoid functional morphology and evolutionary adaptations.
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