Some of these relationships are really interesting.

For example, according to this, an American Robin is more closely related to the Tyrannosaurus rex than the Tyrannosaurus rex was to, say, a Brachiosaur.

I guess I knew birds were closely related to dinosaurs but I didn't think of it quite that way.

The mass extinction intervals are also a little concerning when you think of where we are now. It looks like right about now is when there would be another one, if there was some regularity to them.