Search our site

Custom Search

Tuesday, 12 January 2021

What colour were the dinosaurs?

The discovery that some dinosaurs were feathered rather than the initially-assumed scaly took palaeontology by storm. But the question didn’t end there. We still don’t know the extent to which feathers were found across the dinosaur kingdom. Skin-impressions of some sauropods show hexagonal scales or bony plates, suggesting they were unfeathered, whilst others such as the tyrannosaurus were definitely feathered. And what colour were these scales or feathers? For the most part, we don’t know.

Feathered velociraptor. Matt Martyniuk via Wikipedia Commons
 

Melanophores Ian AlexanderVectorisatio via Wikipedia Commons
Chemical traces have been found in feathers that don’t degrade, because melanosomes found in them reveal colour according to their size and shape (like if white paint was kept in a round tin, black in a square- you could tell what colour the pain had been even if only the tin was left). Still, this only tells us very cursory information, such as that a dinosaur was “brown”, and doesn’t give us detailed information about shade.

Some research into structural colour could reveal the colours of other dinosaurs including scaly ones. The way scales or feathers overap can lead to distinct colours.

How?

These microstructural (and sometimes smaller) details can interact with waves of light, rather like an oil slick that produces a rainbow. They can reflect, refract, or even diffract light, and so that material looks coloured, even though pigment may not be present. Recent discoveries of structural colour in unexpected materials have allowed scientists to guess at what colour dinosaurs were, and has led to the conclusion that it may be more common than previously believed. It is also possible that some things exhibit structural colour seen only by insects with UV vision.

Unfortunately, structural colour doesn’t always preserve well, leading to more mysteries: because a dinosaur with black pigment could actually have looked shiny blue or green, because of structural colour!
 
The morphocypris butterfly has wings with structural colour. Notafly via Wikipedia Commons.
 


 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
It also depends on the eyes that are seeing it. Weirdly, evidence from marsupials suggests mammals once saw in UV, like bees. Scientists found inactive genes which, when expressed in a lab absorbed in the UV and near UV region. This is the same pattern of genes as those found in humans with inactive S cones – making them colourblind. This means that dinosaurs could have had vivid colours in the UV but dull in the visible, or the other way round, depending on the visual acuities of predators and prey. Again, this is a mystery to be explored.

So what are we left with?

We do know the colours of some dinosaurs. Microraptors were black and iridescent like a crow, and anchiornis matt black and white with some orangey-red bits. But most specimens are not well enough preserved to give these clues.

We can make assumptions based on animals that are around today. Stealth predators and prey animals need to be camouflaged, so dull colours and browns and greys are likely. Meanwhile, signalling systems like frills are often brightly and multicoloured. But know? We may never know.

To find out more about dinosaurs, check out our article on birds. Or this blog post on tyrannosaurs.

No comments:

Post a comment