Fossilized melanosomes and the colour of Cretaceous dinosaurs and birds

Ginger group dinosaurs A series of striking 'feathered dinosaur' fossil discoveries from the Cretaceous Jehol Group sediments of China has revolutionized thinking about the evolution and diversity of dinosaurs and early birds. But it has been suggested that some of the structures that are not obviously feathers might actually be strands of collagen from under the skin. Zhang et al . refute this notion by demonstrating the presence in these structures of melanosomes — the characteristic bodies that give feathers their colours. Not only do they show that the feather-like structures of dinosaurs such as Sinosauropteryx really are akin to feathers, but also they can speculate in an informed way about their colour — which it seems was reddish brown or ginger. Here the presence of melanosomes — characteristic bodies that give feathers their colour — is demonstrated in feathers and feather-like structures of fossil early birds and dinosaurs from the Early Cretaceous Jehol Group of China. Not only is it shown that the feather–like structures of dinosaurs such as Sinosauropteryx really are akin to feathers, it is also possible to speculate in an informed way about their colour. Spectacular fossils from the Early Cretaceous Jehol Group 1 , 2 of northeastern China have greatly expanded our knowledge of the diversity and palaeobiology of dinosaurs and early birds, and contributed to our understanding of the origin of birds, of flight, and of feathers. Pennaceous (vaned) feathers and integumentary filaments are preserved in birds 3 , 4 , 5 and non-avian theropod dinosaurs 6 , 7 , 8 , 9 , 10 , 11 , 12 , but little is known of their microstructure. Here we report that melanosomes (colour-bearing organelles) are not only preserved in the pennaceous feathers of early birds, but also in an identical manner in integumentary filaments of non-avian dinosaurs, thus refuting recent claims 13 , 14 , 15 , 16 that the filaments are partially decayed dermal collagen fibres. Examples of both eumelanosomes and phaeomelanosomes have been identified, and they are often preserved in life position within the structure of partially degraded feathers and filaments. Furthermore, the data here provide empirical evidence for reconstructing the colours and colour patterning of these extinct birds and theropod dinosaurs: for example, the dark-coloured stripes on the tail of the theropod dinosaur Sinosauropteryx can reasonably be inferred to have exhibited chestnut to reddish-brown tones.