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Updated: May 7, 2026
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Assessing Forelimb Function after Unilateral Cervical SCI using Novel Tasks: Limb Step-alternation, Postural Instability and Pasta Handling
Published on: September 16, 2013
Forearm posture and mobility in quadrupedal dinosaurs.
Collin S VanBuren1, Matthew Bonnan
1Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, Ontario, Canada.
Plos One
|September 24, 2013
Summary
Dinosaur forearm mobility was limited, even in quadrupedal species. Quantitative analysis of the radius bone reveals unique adaptations, suggesting bipedal ancestry influenced forelimb posture diversity.
Area of Science:
- Paleontology
- Biomechanics
- Evolutionary Biology
Background:
- Quadrupedality evolved independently multiple times in dinosaurs, yet limb anatomy and function constraints, particularly forearm rotation, are poorly understood.
- Previous qualitative studies on dinosaur forearm posture and mobility lack quantitative data, leading to inconsistent conclusions.
Purpose of the Study:
- To quantitatively assess antebrachial (forearm) posture and mobility in dinosaurs using the radius bone.
- To investigate the relationship between radial morphology and pronation/supination ability in extinct and extant taxa.
Main Methods:
- Employed a geometric morphometric approach analyzing the proximal radial head's shape using sliding semi-landmarks.
- Measured the radius bone's curvature angle across a diverse sample of mammals, dinosaurs, squamates, birds, and crocodilians.
Main Results:
- Radial head morphology indicated limited pronation/supination in quadrupedal ceratopsians, bipedal ornithopods, and theropods; sauropodomorphs possessed unique radial morphology suggesting limited rotation.
- Radius curvature analysis revealed that no dinosaurian clade could cross the radius over the ulna, indicating parallel antebrachial elements in all quadrupedal dinosaurs.
Conclusions:
- The bipedal origins of quadrupedal dinosaur clades may have permitted greater forelimb posture diversity than previously assumed.
- Future research on dinosaur posture should move beyond simplistic extant dichotomies to appreciate evolutionary variations.
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