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Re: Asilisaurus kongwe




--- On Fri, 3/5/10, Augusto Haro <augustoharo@gmail.com> wrote:

> From: Augusto Haro <augustoharo@gmail.com>
> Subject: Re: Asilisaurus kongwe
> To: keesey@gmail.com
> Cc: dinosaur@usc.edu
> Date: Friday, March 5, 2010, 3:17 AM
> If the Silesauridae is the sister
> group of the Dinosauria, then its
> presence in the Anisian indicates an older age for the
> Dinosauria (I
> mean, as old as the Silesauridae). Also, for pterosaurs,
> and the
> stem-taxa leading to Scleromochlus, Lagerpeton and
> Marasuchus but not
> dinosaurs.
> 

Not necessarily, and i think the authors do discuss this very briefly.

'At the moment' silesaurids are the sister taxon to Dinosauria, the 'at the 
moment' part is important because if various other new archosaurian taxa were 
discovered, and found closer to dinosaurs than to silesaurids, these new taxa 
would become progressively closer sister taxa to dinosaurs (than silesaurids 
are). What this means in terms of age is that the oldest dinosaurs need not 
have been as old as the oldest silesaurids (re-note that dinosauria is 
node-based [Ornithischia + Saurischia], thus allowing for the above mentioned 
hypothetical sister taxa to be identified, and hence better constraining the 
earliest age for dinosaurs in future).