Re: Basal Ornithischia and Stegosauria

[David Marjanovic <david.marjanovic@gmx.at>]

> So what is the PC term for what used to be called an "advanced
> tyrannosaur" and has more recently been called a "derived
> tyrannosaur"?

Nothing. :-) I'll keep talking about "derived tyrannosaurs", though, because 
they are derived across the board ( = have many apomorphies).

> Are still allowed to talk about "basal tyrannosaurs".

The correct definition for "basal" seems to be "far away from what I'm 
interested in at the moment". This is how you get statements in the 
literature that "mammals are the basalmost living amniotes" from this tree:

--+--mammals
 `--+--turtles
    `--+--lepidosaurs
       `--+--crocs
          `--birds

I'll continue to use it this way. But there are people who want to beat this 
out of your head, probably because some people use "basal" in exactly the 
same way they previously used "primitive".

Interestingly, I once came across an attempt to save the honour of 
"primitive": sharks being primitive merely meant "that they have existed for 
a long time". Didn't catch on.