RE: no marine dinos/no viviparous dinos.

["Ken Kinman" <kinman@hotmail.com>]

   But would such physiological constraints hinder the evolution of 
ovoviviparous dinosaurs?
         ------ Ken
****************************************
> > With all due respect:
> >  We do not forget physiology and its constraints. Turtles and crocodylian 
> > embryos obtain most of the calcium for the development of their skeleton 
> > from the egg shell (Packard et al. 1977),  while lepidosaurs do not 
> > (Oelofsen 1978). Thus the lepidosaurs can eliminate the shell and become 
> > viviparous (lots of lizards and snakes) while turtles and crocodilians 
> > cannot , and no viviparous birds also (Blackburn and Evans 1986).


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