The colour of dinosaurs is something that has long been pondered but thought to be an impossibility to know for sure. It is something that has encapsulated people for so long because colouring in a dinosaur brings it to life in our imaginations. It reminds us it was a real animal and not a pile of fossilised bones.
Luckily, I'm writing this post at a time when we've advanced enough to be able to give these dinosaurs life through colour, so let's explore the question: What colour were dinosaurs?
Now, an animal that lived 66 million years ago who left nothing behind other than bones makes it very difficult to figure out things like colouring...rather selfish if you ask me. But, that doesn't mean we can't make some educated guesses.
No animal is coloured in a certain way by accident, it is something that has evolved for a purpose. The reasons behind these colourings do vary, but will come down to one of two: camouflage or display...to be seen or not to be seen? That is the question.
For camouflage, any animal will want to blend in with the surroundings of its habitat, so one size doesn't fit all, but their only a limited number of colours seen in any terrestrial biome. The colours you would want would be (what d'you know) Earth tones, such as browns, greens and greys, the extent of which depends on if you inhabit a desert, savannah or a forest.
Given that many dinosaurs were either the hunter or the hunted, blending in with these environments was key for avoiding detection. Patterns is something that can also be loosely predicted depending on the environment. If a dinosaur is living on a wide open plain, fewer patterns mean that it will blend in to that background that has less variation of light. Alternatively, if a dinosaur lives in a temperate forest where direct sunlight is sporadic, stripes may be the better option in order to blend in with the shadows being cast by all those branches.
Another pattern seen quite often is something called counter-shading. This is where the animal has a lighter belly than its back, so that the shadows on its underside appear less contrasted. The more open, direct sunlight the animal lives in, the more abrubt the counter-shading appears. In fact, this is actually something we have found direct evidence for in a certain dinosaur, but I'll get onto that soon enough.
The other reason would be for display. Now, if dinosaurs were more closely related to mammals, it would be much easier to predict those colours, since mammals rely less on appearance for display and more on noises or actions, whether that be when they're threatened or trying to mate.
However, dinosaurs are not mammals. In fact, the only window we have that is alive today to compare to are birds, which are avian dinosaurs. Birds do things very differently, relying on extravagant plumage and/or bright colours to get their point across (which would either be 'back off, buddy' or 'come closer, honey). Likelihood is that birds inherited this approach from their dinosaurian ancestor, which makes colouring in dinosaurs far more complicated and unpredictable.
They could have had hugely complex structures covered in any colour on the spectrum, especially dinosaurs whose display tools are found on their bones, such as ceratopsians or stegosaurians. Overall, this revelation suddenly makes things a lot more unpredictable all over again.
Don't worry, not all hope is lost! Believe it or not, while we don't know what colour most dinosaurs were, we do know the colour of some for certain.
On some special occasions, we have finds of exceptional preservation. Some of these finds preserve much more than bone, such as when find fossilised melanosomes. Melanosomes are cells within an animal's body that are responsible for the production, transport and mixing of melanin, which absorbs certain waves of light depending on how it is synthesised and shaped. In other words, these are 'colour cells'. It has only been in the last decade or so that technology has come far enough that we can actually detect these cells in fossilised form, so who knows how many we may have missed.
Nonetheless, these advances mean we know for certain the colour of a few dinosaurs and a few is better than none.
The first of these dinosaurs is Psittacosaurus.
Psittacosaurus mongoliensis is a basal ceratopsian from all over Asia during the Early Cretaceous. One specimen of Psittacosaurus, thought to have been illegally exported from China, was found with actual preserved skin as well as feathers. This dinosaur was mostly scaly, but had a series of quills along the back of it tail, hinting at an ancestral feature of all ceratopsians.
The skin contained a wide distribution of melanosomes and, after scanning these with special reflective light, it was found that Psittacosaurus was a dark brown, with soft counter-shading on its belly.
Another dinosaur with preserved melanosomes is Microraptor zhaoianus.
This dinosaur, as the name suggests, was a tiny dromaeosaur, around the size of a crow. Not only that, but it also is thought to been able to glide between trees using its four wings. Similarly to Psittacosaurus, a specimen of Microraptor was found showcasing fossilised feathers that still contained some melanosomes. Using similar techniques, it was found that Microraptor was an iridescent black, blending just enough into a low light forest while using that iridescence for a more subtle mating display. Microraptor here is keeping it tasteful.
Another dinosaur that shows a much more loud kind of iridescence is Caihong juji.
This dinosaur is, again, a small paravian from the Late Jurassic China. Small enough to sit in your hand, Caihong was able to preserve enough melanosomes to show that it was also iridescent black...except for the head and chest. The melanosomes here were a similar shape to those found on much more colourful iridescent birds such as hummingbirds. You stay loud and proud, little guy.
Next on this list, we have Sinosauropteryx prima.
Straight away, you can see a lemur tail-like pattern running along this dinosaur's tail. In fact, Sinosauropteryx was actually the very first instance of palaeontologists confidently stating what colour and pattern was on a dinosaur. This little guy was a compsognathid from the Early Cretaceous and was covered in filament-like feathers that would have resembled fur. Not only were melanosomes studied on certain specimens, but the specimens (as you can see above) were simply screaming colours on a macro-level. Sinosauropteryx, again, had countershading, with a light beige underside, brown topside and a series of rings going along its unusually long tail.
Want to go a little bit bigger? Well, what about the famous 'mummified' nodosaur, Borealopelta markmitchelli?
This particular dinosaur was a nodosaur, which is one of two groups of ankylosaurs. As you can see, it had plenty of armour, but did in fact lack a tail club. At around 5.5 m (18 ft) long, this particular specimen of Borealopelta is thought to have somehow sunk to a shallow sea floor pretty quickly after it died, landing upside down and having its skin and internal organs preserved by the quickly burying sediment. Not only was armour arrangement preserved in perfect detail, melanosomes showed it was a counter-shaded, reddish brown.
So, there we have it. we may not know the exact colour and patterns of all our favourite dinosaurs and the bird relation may make it nearly impossible to predict, but don't lose hope that one day, an exceptionally preserved specimen of dinosaur will show its rich colourisation through melanosomes, getting us closer to imagining how it would have been when it was alive.
Until next time!