The Dinosaur Syrinx?

[Sim Koning <simkoning@msn.com>]

  Below is a link to a paper on the ontogeny of vocalization in duck and chick 
embryos. According to the paper, the clavicular air sac is not essential for 
sound production in birds and that the constriction and vibration of the 
tympaniform membranes during exhalation is the basic or primary source of sound 
production.
 
http://onlinelibrary.wiley.com/doi/10.1002/jez.1401680303/abstract
 
  Since sound production in dinosauria may not have been contingent upon the 
existence of a clavicular air sac, I suspect that tympaniform membranes may 
have been a basal characteristic of ornithodirans. The presence of tympaniform 
membranes in the bronchial tubes of ornithodirans would have allowed these 
archosaurs to capitalize on their relatively long s-curved necks. The existence 
of a homologous structure in sauropods would have allowed them to use their 
extremely elongated trachea as a massive resonating tube; this is similar to 
the greatly elongated trachea found in some bird species. Advanced theropods 
may have had an almost avian clavicular air sac driven syrinx, as evidenced by 
the likely presence of a clavicular air sac in Aerosteon. Some hadrosaurs may 
have used their head crests as resonators in much the same way modern birds 
make use of resonator sacs while producing sounds with a closed mouth. 
 
  With the above possibilities considered, I feel dinosaur animators and 
artists should feel free to restore dinosaurs with a wide range of 
vocalizations. 
 
 
Simeon Koning