Dinosaurs had orange feathers, according to BBC News, Nature News, ScienceNOW and ScienceDaily 27 Jan 2010. Researchers in China and UK claim to have found evidence that some dinosaurs had gingery-brown feathers and one, named Sinosauropteryx, had a striped tail. This dinosaur is described by Mike Benton from the University of Bristol, UK as having “a very clear rim of feathers running down the top of its head like a Mohican, all the way along its back.”
The researchers found fossilised granules, the size and shape of melanosomes in the “feathers” found with this fossil. Melanosomes are granules that contain melanin, the brownish-black pigments found in skin, hair and feathers and come in two shapes depending on what colour pigment they produce. Round melanosomes produce a russet coloured pigment, elongated ones produce grey-black pigment. The researchers had previously found melanosomes in the fossilised feathers of a bird named Confuciusornis. The melanosomes were not evenly distributed along the tail of Sinosauropteryx. There were alternating bands with and without them, indicating the creature had russet and white stripes on its tail.
Mike Benton commented that the presence of melanosomes confirms that the filaments “really were feathers”. He explained; “Critics have said that these visible spiny structures could be shredded connective tissue. But the discovery of melanosomes within the bristles finally proves that some early dinosaurs were indeed feathered.” He also said: “Our research provides extraordinary insights into the origin of feathers. In particular, it helps to resolve a long-standing debate about the original function of feathers – whether they were used for flight, insulation, or display. We now know that feathers came before wings, so feathers did not originate as flight structures. We therefore suggest that feathers first arose as agents for colour display and only later in their evolutionary history did they become useful for flight and insulation.”
However, evolutionary biologist and bird expert Alan Feduccia of the University of North Carolina, Chapel Hill, disagrees. He has long been sceptical of claims that dinosaurs had feathers and argues Benton and his colleagues “make a leap of faith going from Confuciusornis to Sinosauropteryx.” Feduccia suggests that if the granules really are melanosomes they could have come from skin.
Editorial Comment: Feduccia is correct. Even if the fossilised granules are melanosomes that does not prove the filaments on Sinosauropteryx were feathers. It is not pigment that makes feathers – it is the structure, and these pointed fibres simply do not have the structure of feathers. Feduccia and colleagues have closely studied this fossil and concluded that the filaments were collagen fibres, not feathers. There is no reason why melanosomes could not have coloured skin or skin-derived structures, just as they do in many kinds of living creatures today. (Ref. Pigmentation, fossils)
Evidence News 24 Mar 2010