floating archosaurs

[GSP1954@aol.com]

Folks should know that in the only large scale survey of bird specific 
gravities G Hazelhurst & J Rayner 92 Paleobiology 18:447-63 observed an average 
SG 
of 0.73. I suspect this may be an overly low value because the sacs were 
inflated to their maximum when we want the average between max and minimum. 
Richard's observations on chickens seems too dense considering avian 
pneumacity, but 
the lightness of birds (and especially pterosaurs) should not be exaggerated. 
Bird skeletons make up the same % of total body mass as those of mammals. As 
true of many things I discuss these issues in DA.

G Paul