Sometimes it is enough just to roll up some monsters and throw them at the player characters. On the other hand, musing about the origins of the fiercest creatures in your campaign can also be a fun mental exercise. Furthermore, if you sometimes like to throw your player's characters into the prehistoric past of your world, and allow them to discover fossils in the here-and-now of your campaign, then a bit of evolutionary musing can even pay off at the table. A flurry of recent articles on the ancestry of Great White sharks might be just the thing to get your paleontological juices flowing. Read more here, here, and here!