Coalacanths -- Prehistoric Fish vs Evolution.?

In YA News today, I read an article of a fisherman in Indonesia who caught a large fish, whose fossil records date back 360 million years ago. Most scientists thought that the fish had become extinct with the dinosaurs, but here we are. It is interesting to note, in a period of over 360 million years the Coalacanth has remained a Coalacanth, and not evolved into lets say, a vermicious knid...what's up with that? How can this be? Is evolution selective? Why no evolution for some species, yet for others they are like Transformers? Kisses!!!!