World of Dinosaurs/Basal vs Derived

The terms "basal" and "derived" are relative. They only make sense if you provide the context - what clade are you talking about? Basal animals have the traits required to belong in their clade, but otherwise have a lot in common, still, with that last common ancestor that unites the clade. Derived animals have features really different from the last common ancestor at the base of their clade. Examples: Coelophysis is a derived tetrapod, but it's a basal dinosaur. Archeopteryx is a derived dinosaur, but it's a basal bird. Come up with your own examples. Within any clade of animals, what is a good example of a basal animal? What is a good example of a derived animal?