Using Imagemagick to create an animated gif from .png files

With R, I created a series of charts, each representing a sample snapshot at a given time.  I wanted to animate them, and found a wonderful command-line set of utlities called ImageMagick.  I had to jump through quite a few hoops to install ImageMagick on Mac OS X (will post details if/when I get the time), but I'm glad I did.

Here's a sample session where I combine the files into an animate gif:

~/r/tmat>ls
tmat02.png  tmat04.png tmat06.png  tmat08.png tmat10.png  tmat12.png tmat14.png  tmat16.png tmat18.png  tmat20.png
tmat03.png  tmat05.png tmat07.png  tmat09.png tmat11.png  tmat13.png tmat15.png  tmat17.png tmat19.png
~/r/tmat>convert -delay 20 -loop 0 * page_transition.gif