I think that the development of the vocal center in the brain is the best place to begin your search. There is some good indocasts of theropod brains.
Hope this helps: John Schneiderman john-schneiderman@cox.net On Sun, Dec 29, 2013 at 4:20 PM, Ian Paulsen wrote:
HI ALL:A friend of mine wonders if anyone on the paleo lists know who may be studying the evolution of the syrinx? She's interested to know if anyone knows when this structure first appeared?sincerely -- Ian Paulsen Bainbridge Island, WA, USA Visit my BIRDBOOKER REPORT blog here: http://birdbookerreport.blogspot.com/