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RE: Uncinate processes ref



> From: owner-dinosaur@usc.edu [mailto:owner-dinosaur@usc.edu]On Behalf Of
> John Hutchinson
>
> I think someone asked about this recently on the list; longstanding mystery
> about uncinate process function.  Well here's one new study of it, from:
> http://jeb.biologists.org/cgi/content/full/208/5/i-a?etoc
>
> BONY BIRDS BREATHE BETTER
>
> Yfke van Bergen
>
> A fascination with dinosaur skeletons has led Jonathan Codd of Bonn
> University to new insights into birds' breathing physiology. Codd was
> puzzled by the role of velociraptors' uncinate processes, `small ossified
> structures projecting like little handles from their ribs.' Reflecting on
> the evolutionary link between dinosaurs and extant birds, he hoped that our
> feathered friends might provide him with some clues regarding the function
> of these strange structures. When Codd investigated the muscles associated
> with the uncinate processes of giant Canada geese, he found that these bony
> projections are integral to bird breathing mechanics (p. 849).
>
[snip]

> The team were particularly intrigued to see increased appendicocostal
> activity in sitting geese. Codd explains that when birds sit, their sternum
> movement is restricted, making breathing difficult. `The increased
> appendicocostal activity we noticed suggests that when the sternum's
> movements are restricted, like when birds are sitting on their nests, this
> muscle causes the rib cage to flare sideways and draw air into the birds'
> lungs' he says. So thanks to this muscle, birds can breathe easy during
> those long periods of egg incubation.
>
> References
>
> Codd, J. R., Boggs, D. F., Perry, S. F. and Carrier, D. R. (2005). Activity
> of three muscles associated with the uncinate processes of the giant Canada
> goose Branta canadensis maximus. J. Exp. Biol. 208,849 -857.[CrossRef]

Interesting. Given that big ossified uncinates show up at the base of 
Maniraptora, but (not yet) below among theropods, and given
that direct evidence of brooding ALSO shows up at the base of Maniraptora, 
perhaps this suggests a similar breathing mode while
brooding for oviraptorosaurs, deinonychosaurs, and birds.

                Thomas R. Holtz, Jr.
                Vertebrate Paleontologist
Department of Geology           Director, Earth, Life & Time Program
University of Maryland          College Park Scholars
        Mailing Address:
                Building 237, Room 1117
                College Park, MD  20742

http://www.geol.umd.edu/~tholtz/
http://www.geol.umd.edu/~jmerck/eltsite
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