Drab cuckoos retain the melanosome types of brilliantly coloured relatives

Abstract Structural colour is widespread in animals, yet we know relatively little about its evolution and development. We shed light on the evolution of structural barbule colour (often referred to as iridescent structural colour) by describing feather nanostructures responsible for plumage colours in the cuckoos (family Cuculidae). The melanosomes found in feathers with structural barbule colour have specialized shapes: hollow rods, thin solid rods, hollow platelets or solid platelets. In cont