Eusthenopteron is a very cool fossil. I showed my class a picture of a Coelocanth fossil that had front fins that had 5 bones similar to hand bones. Very cool.
What really blew my kids away was when I told them that these creatures still exist! An organism that shows transitional features and has happened to live in the west Indian Ocean off the east coast of Africa for millions of years. It hasn't evolved further because it hasn't had to. It's suited for its environment. Had the environment changed, it would have had to adapt or die. But, the ocean environment has been very similar for millions of years.
That's the interesting thing and what a lot of people misunderstand: if an animal is suited to its environment, the environment doesnt change, and no mutations pop up that are useful for survival, the species survives as is.
If the environment changes, then the organism can either benefit from mutations that may provide a useful advantage in survival, or, if there are no helpful mutations, it dies. It either ADAPTS or DIES. So many have died and are now extinct. Only the fittest survive to reproduce.
Lovely work, Cofty.