Re: dinosaur argument

[Bill Adlam <bill.adlam@st-peters.oxford.ac.uk>]

As regards pterosaurs being dinosaurs or not, it isn't a difference of opinion,
nor a factual disagreement.  For the past hundred years or so the Dinosauria 
has been defined so as not to include pterosaurs, there are now some people 
(not including me) who find it more convenient to group them together.  See
Peter's message:

On Fri, 12 May 1995 Stang1996@aol.com wrote:

> P.S. What does Plesiomorphic mean, what is the opposite of Plesiomorphic?

It means with the original ('primitive') character state (e.g. 4 legs is/are 
plesiomorphic for tetrapods).  The state itself or the having of it is 
plesiomorphy.  It's Greek for near-form.  The opposite is apomorphic (I don't 
know what apo means, I think it's something like off or away).  Watch out also
for synapomorphies and autapomorphies, which are apomorphies that have and 
haven't been found in anything else, respectively.  (Syn = together, aut = 
self.)

It's all cladist-speak, of course :-)
                                                                Bill Adlam