ichthyosaurs & sauropterygians

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

    I'm pretty convinced now that choristoderes are archosauromorphs (and 
even Dilkes says the case for excluding them from Sauria is weak).
    So I am now tackling the more difficult question of where to place 
Thalattosaurs, Ichthyosauromorphs (apparently incl. Hupehsuchus) and the 
Sauropterygians.
     Although sauropterygians seem to be saurians, there seems to be a very 
big split on whether they are lepidosauromorphs or archosauromorphs.  And if 
thalattosaurs and ichthyosaurs end up in the same saurian clade as 
sauropterygians, there would still be the problem of deciding if all three 
of these groups form a single euryapsid subclade or not.
     Anyone have any particularly strong synapomorphies they feel indicates 
whether they are lepidosauromorphs or archosauromorphs?
                  ------Ken Kinman

________________________________________________________________________
Get Your Private, Free E-mail from MSN Hotmail at http://www.hotmail.com