Posts Tagged 'Nature'

Dinosaurs, now available in colour

Among the near interminable questions one has to answer as a palaeontologist such as ‘what was the biggest dinosaur?’ and ‘how fast were they?’ is ‘what colour were they?’. The stock answer is always, ‘well we don’t know, but we can make an educated guess based on living animals’. The new answer is ‘we look at the microstructure of the melanosomes in the feathers’.

Two different kinds of melanosomes from fossil feathers. Modified from Zhang et al., 2010.

Yes, a new paper in Nature today reveals how we might yet be able to work out the colours of some dinosaurs and birds thank to the quite incredible preservation of various animals in places like Liaoning. Melanosomes are tiny organelles that hold colour pigments and help give feathers their colours (more on them here, something written for this paper) and these have now been found in some feathers from ancient fossil beds. For a start this is likely to be the final nail in the coffin that some feathers are just collagen fibers or even fakes as some have claimed, since you know, having a microstructure identical to that seen in modern feathers seems rather unlikely that something 0.005 of a millimetre could be faked.

More importantly and excitingly though, some melanosomes in extant birds vary in size and shape according to the pigments they house. In other words, you can tell what colour they are by their shape. If it’s one shape it’ll be one colour, a different shape, a different colour. That means that if you have a feather from a dinosaur say, you can tell what colour it was by the shape of the preserved melanosomes.

While some fossil feathers already show a striping pattern of light and dark this only tells us that one part was lighter than the other, the actual colours were unknown so it could have been blue and yellow or green and brown or even black and white. The presence of identifiable melanosomes with known structures can help to work out the colours of the animals that bore them. Similar work has admittedly already been done by another research team on feathers of similar antiquity, but this is the first time it’s been applied to dinosaurs.

Inevitably the results are not going to be that dramatic. Only a small part of some individual feathers have been analysed and feather colour is made up of more than just the melanosomes. Nevertheless, some distinctions can be made and the authors note that it looks like Sinosauropteryx for example had a red-brown tail (or at least some russet tail feathers). It’s in one sense a small step forwards, but in the long term it could be one of the most important for finally revealing the colour of the dinosaurs.

Zhang, F. et al. 2010. Fossilised melanosomes and the colour of Cretaceous dinosaurs and birds. Nature. doi:10.1038/nature08740doi:10.1038/nature08740

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