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Re: Semicircular canal design and locomotion

Guy Leahy wrote:
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.
Several things to note. . .

The way the authors of the PNAS study coded agility might leave something to be desired - they were ranked from "extra slow" to "fast" based on field and video observations. Not sure how I'd improve this though - perhaps the next step would be to track frequency of movement or something like that.

Anyhow, we have good evidence of this for many dinosaurs - see the following SVP abstracts and web pages following exactly your line of questioning:
Sipla, J.S.*, J.A. Georgi, and C.A. Forster (2004) The semicircular canals of dinosaurs: Tracking major transitions in locomotion. Journal of Vertebrate Paleontology. Suppl. 24:113.

*Sipla, J.S.*, J.A. Georgi, and C.A. Forster (2003) The semicircular canal dimensions of birds and crocodilians: Implications for the origin of flight. Journal of Vertebrate Paleontology. Suppl. 23:97.

And, see the summaries presented at:

Head Games Show Whether Dinos Went on Two Legs or Four <http://gibbon.anat.sunysb.edu/Department/students/science2.pdf>, Erik Stokstad, Science 306: 1466.

Peering Into Ancient Ears <http://gibbon.anat.sunysb.edu/Department/students/science1.pdf>, Erik Stokstad, Science 302: 770-771.

Sipla will defend his dissertation on the bird semicircular canals on Friday. All of your questions will be answered then (and in Georgi's dissertation defense later this year. . .).