Animal Cognition - Fishes are among the oldest and most diverse groups of vertebrates, encompassing a vast array of species that differ in morphology, ecology, and behavior. While such diversity...

Yes. Multiple exceptionally preserved Cambrian fossils indicate that early vertebrates had four eyes: two large lateral eyes and a second, smaller median pair on the top of the head. In these fossils, all four were camera-type organs with pigment and lenses, and the median pair corresponds to the ancestral pineal complex that later became non-visual in most lineages. The new evidence comes from myllokunmingid vertebrates about 518 million years old described in…