How did flatfishes, with both of their eyes on one side of their head, evolve? The new discovery, described in the Journal of Vertebrate Paleontology, finally solves this mystery.
Dr Friedman’s fossil fish, named Heteronectes (meaning ‘different swimmer’), was found in 50 million year old marine rocks from northern Italy.
The study provides the first detailed description of a primitive flatfish, revealing that the migrated eye had not yet crossed to the opposite side of the skull in early members of this group. Heteronectes, with its flattened form, shows the perfect intermediate stage between most fish with eyes on each side of the head and specialized flatfishes where both eyes are on the same side.