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Femoral head trabecular bone structure in two omomyid primates
Timothy M Ryan1, Richard A Ketcham
1Department of Anthropology, The University of Texas at Austin, 78712, USA. tmryan@duke.edu
Journal of Human Evolution
|August 6, 2002
Summary
Analyzing primate femoral heads reveals distinct locomotion patterns in Omomys carteri and Shoshonius cooperi. Trabecular bone structure suggests Omomys was quadrupedal, while Shoshonius may have been a leaper.
Area of Science:
- Paleontology
- Primate Anatomy
- Biomechanics
Background:
- Three-dimensional trabecular bone structure analysis offers insights into primate locomotor behaviors.
- Understanding extinct primate locomotion is crucial for evolutionary studies.
Purpose of the Study:
- To quantify and compare the three-dimensional trabecular bone architecture in the femoral heads of Omomys carteri and Shoshonius cooperi.
- To relate these bone structures to locomotor behaviors by comparing them with extant strepsirrhine taxa.
Main Methods:
- High-resolution X-ray computed tomography was used to scan fossil primate femoral heads.
- Trabecular bone volume fraction (BV/TV) and fabric anisotropy were quantified in three dimensions within defined volumes of interest.
- The star volume distribution method was employed to assess structural anisotropy.
Main Results:
- Omomys carteri exhibited a high BV/TV and lorisine-like isotropic fabric, suggesting quadrupedal locomotion.
- Shoshonius cooperi showed a uniform BV/TV and galagine-like increasing anisotropy, consistent with leaping or occasional leaping-quadrupedal behaviors.
- Despite external anatomical similarities, the trabecular bone structures indicate divergent hip joint loading and locomotor behaviors.
Conclusions:
- Trabecular bone architecture in Omomys and Shoshonius femoral heads reflects distinct locomotor adaptations.
- This study highlights the utility of microstructural bone analysis for inferring the behavior of extinct primates.
- The findings suggest significant differences in the locomotor behaviors of Omomys and Shoshonius, despite their shared external postcranial anatomy.