How Eye Pigments Shaped Vertebrate Evolution: 300-Million-Year-Old Fish Fossils Reveal Melanosome Secrets

University College Cork paleontologists have uncovered a direct link between the evolution of fish and the shape, location, and abundance of melanosomes—tiny melanin-rich granules found in the eye. Their study, based on 300-million-year-old fossil fish, suggests these microscopic structures have played a key role in vertebrate evolution since the major fish groups first emerged around 445 million years ago. The research highlights how melanosomes, long known for their role in coloration, also influence visual function and adaptation. By surviving in ancient fossils, they offer a rare window into the sensory biology of early vertebrates. This discovery matters because it shifts the focus from external appearance to internal eye physiology, revealing how vision may have driven evolutionary success. The findings could reshape how scientists interpret fossil pigments and their functional significance. Ultimately, the study underscores the deep evolutionary roots of eye pigmentation and its lasting impact on vertebrate life.