> What's the definition
of:
>
> --- apomorphy?
A
derived character state (i.e., an evolutionary novelty).
> ---
synapomorphy?
A shared derived character state (i.e., an
evolutionary novelty found in more than one taxon, which evolved in their
common ancestry).
Note
that a websearch (or use of some sites like the Dinosauricon or Dinosauria
On-line or university class websites) might give you answers to these and many
other questions.