This image illustrates the simplified family tree showing the gradual evolution of flatfish eye asymmetry. The drawings show the most ancient fossil (left) with symmetrical eye sockets. Amphistium and Heteronectes, the reexamined fossil fish, show asymmetrical skulls, but maintain eyes on opposite sides of the head. The other two fish drawings show the asymmetrical eye locations and skull of the most current flatfish species. Credit: Matt Friedman, University of Chicago