Re: Are dinosaurs really reptiles?

[K and T Dykes <ktdykes@arcor.de>]

<<Still under this topic, but a slightly sister-group question: how far 
back - in time and species - was the split between synapsids and all the 
other amniotes? And what was the "ur-amniote" like? Is there any major 
consensus on this?>>

Both synapsids and reptiles (sauropsids according to some) are known from 
the Upper Carboniferous at around (if I remember correctly) 310-315 million 
years ago.  They were distinct lineages by then, so the split happened by 
that time at the latest.