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Semicircular canal design and locomotion

The full article is available at this link:


Published online before print June 18, 2007
Proc. Natl. Acad. Sci. USA, 10.1073/pnas.0704250104

Anthropology-Biological Sciences
The primate semicircular canal system and locomotion 
( generalized least-squares analysis | mammals |
vestibular system ) 

Fred Spoor *, Theodore Garland Jr. , Gail Krovitz ,
Timothy M. Ryan , Mary T. Silcox ¶, and Alan Walker ||

*Department of Anatomy and Developmental Biology,
University College London, Gower Street, London WC1E
6BT, United Kingdom; Department of Biology, University
of California, Riverside, CA 92521; eCollege, 4900
South Monaco Street, Denver, CO 80237; Department of
Anthropology, Pennsylvania State University, 409
Carpenter Building, University Park, PA 16802; and
¶Department of Anthropology, University of Winnipeg,
515 Portage Avenue, Winnipeg, MB, Canada R3B 2E9

Contributed by Alan Walker, May 8, 2007 (sent for
review December 23, 2006)

The semicircular canal system of vertebrates helps
coordinate body movements, including stabilization of
gaze during locomotion. Quantitative phylogenetically
informed analysis of the radius of curvature of the
three semicircular canals in 91 extant and recently
extinct primate species and 119 other mammalian taxa
provide support for the hypothesis that canal size
varies in relation to the jerkiness of head motion
during locomotion. Primate and other mammalian species
studied here that are agile and have fast, jerky
locomotion have significantly larger canals relative
to body mass than those that move more cautiously.

How many dinosaurs do we have good evidence for this
structure?  Would it be possible to tell, for example,
which birds/theropods were volant versus flightless
based on differences in semicircular canal design? The
article does cite references documenting differences
in semicircular canal structure depending on what type
of flight various birds engage in.

Guy Leahy