Re: Semicircular canal design and locomotion

["Andrew A. Farke" <andyfarke@hotmail.com>]

Guy Leahy wrote:
<snip>
> 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:

http://gibbon.anat.sunysb.edu/Department/students/jsipla.html
<http://gibbon.anat.sunysb.edu/Department/students/science2.pdf>
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. . .).

Andy