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Allometric and metameric shape variation in Pan mandibular molars: a digital morphometric analysis
Michelle Singleton1, Alfred L Rosenberger, Chris Robinson
1Department of Anatomy, Midwestern University, Downers Grove, Illinois 60515, USA. msingl@midwestern.edu.
Anatomical Record (Hoboken, N.J. : 2007)
|January 15, 2011
Summary
Chimpanzee and bonobo molar shapes are indistinguishable when allometric scaling is removed, indicating shared patterns of variation. This finding impacts hominid taxonomy and dietary reconstruction.
Area of Science:
- Paleoanthropology
- Primatology
- Bioanthropology
Background:
- Molar shape variation in fossil hominins is crucial for bioanthropological studies.
- Extant models, particularly chimpanzees (Pan troglodytes) and bonobos (Pan paniscus), are essential for understanding fossil dental variation.
Purpose of the Study:
- To investigate the roles of allometric scaling and meristic variation in molar shape differences between chimpanzees and bonobos.
- To test if these two species share common patterns of metameric variation and molar shape allometry.
Main Methods:
- Geometric shape analysis applied to 3D landmarks of chimpanzee and bonobo mandibular molars.
- Multivariate statistical analysis and 3D visualization of shape vectors.
- Procrustes-based shape variables for crown shape characterization.
Main Results:
- Molar shape variables accurately distinguished species and tooth positions (≥95% accuracy).
- Chimpanzees and bonobos share a common pattern of M(1)-M(2) metameric variation.
- While allometric vectors differ between species, the common allometric trend explains most shape differences; molars are morphometrically indistinguishable without allometry.
Conclusions:
- The study highlights significant similarities in molar morphology between chimpanzees and bonobos, particularly when allometric effects are accounted for.
- Findings have implications for hominid taxonomy and reconstructing diets of fossil hominins.
- Shared allometric trends suggest a common developmental basis for molar shape in Pan species.
