terrestrial & semi-aquatic archosaurs

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

     Is it now the most accepted view that the common ancestor of 
archosaurs was fully terrestrial, and that any semi-aquatic or aquatic 
archosaurs are secondarily so (i.e. reversals).
     Or is it thought likely that the ancestor of archosaurs could have 
been semi-aquatic, and fully terrestrial forms evolved more than once.  In 
particular, is there any evidence that any early Ornithodirans were 
semi-aquatic?
                        ------Ken
P.S.  Are aetosaurs regarded as fully terrestrial, or could their affinities 
for wet muddy habitats indicate a possible semi-aquatic life style?
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