It's been brought up before, but Dunkleosteus makes for a pretty damn good Relicanth evolution. It's not directly related, but both have weird tetrapod-style lobed fins. Also, rock heads. Check this shit out.
That's an artist's interpretation based on fossil evidence.
That's a goddamn Dunkleosteus skull. Its teeth are more like blades fused to its jaws, and it could bite with the force of a Tyrannosaurus Rex. It could physically suck in prey because of the suction created by its ability to open its maw in 1/50th of a second
. It could close it about as quickly. Best part? Damn thing was covered in armor like craggy rocks. (Hint, hint.) See those circles above the jaw? Armored. Fucking. Eye sockets. If there's one real, ancient, fish that can Head Smash like a motherfucker, it's Dunkleosteus.
I'ma go sprite it.