Discovering dinosaur colour patterns

31 October 2017

Interview with

Fiann Smithwick, University of Bristol

As bats can’t give us the chills, perhaps it’s time to talk dinosaurs! Theropods, like the T.rex, were two legged dinosaurs with feathers. An amazingly-well preserved fossil of a small, long tailed theropod has led researchers at the University of Bristol to reveal its colour patterns. By reconstructing the likely colour patterning of the Sinosauropteryx, from a fossil found in China, researchers have shown that it had multiple types of camouflage which helped it to avoid being eaten in a world full of larger dinosaurs. Fiann Smithwick gave Izzie Clarke an idea of what this Theropod would’ve looked like… 

Georgia - Now, as bats can’t give us the chills, perhaps it’s time to talk about everyone’s favour monsters - dinosaurs!  Theropods, like the T.rex, were two legged dinosaurs with feathers. An amazingly-well preserved fossil of a small, long tailed theropod has led researchers at the University of Bristol to reveal its colouring. By reconstructing the likely colour patterning of the Sinosauropteryx, from a fossil found in China, researchers have shown that it had multiple types of camouflage which helped it to avoid being eaten in a world full of larger dinosaurs. Fiann Smithwick gave Izzie Clarke an idea of what this Theropod would’ve looked like…

Fiann - Theropods are the famous meat eating dinosaurs so the classic is, obviously, T.rex (Tyrannosaurus rex). And this little guy Sinosauropteryx was a small theropod - it was only about a metre long, or the largest fossil is around a metre long and it had an exceptionally long tail. We know it was carnivores: it had typically carnivore or meat eating teeth, but also, fantastically, one of the fossils has a complete lizard within its stomach. But now, thanks to the work that we’ve done, we can also say what kind of colour it was.

Izzie - Oh my goodness! How on earth can you work this out because we are talking about millions of years ago?

Fiann - It is incredible. This particular dinosaur is from a fossil formation that’s 126 million years old so it’s pretty impressive we can work out the colours from it, and that’s because of the pigment that gave the animal it’s colour in life. This is melanin which is the same pigment that we have in our skin and hair, and animals have in their hair, and birds have in their feathers. It’s a very stable molecule so it’s very resistant to decay, which means we see it in quite a range of fossils where we have good soft tissue preservation, and that allows us to look at the colour patterns of these animals. And, importantly, there are areas on this fossil that don’t have these pigmented feathers preserved and that’s not because these were naked areas in life that didn’t have any feathers, but we think it’s because only the pigmented feathers preserve due to the fact that melanin is so resistant to decay.

Izzie - Why are all these different colours and pigments so important?

Fiann - It’s important because we can determine some key colour patterns on the dinosaur that we know exist in modern animals. And that allows us to make comparisons and attempt to understand the behaviour of the dinosaurs, and also why it may have evolved these and what that says about the environment that it lives in.

One of which was countershading. This is having a dark back and light underside; it’s a form of camouflage. So blending in better to the background if you have a dark back and you’re being viewed from above, this will clearly blend in better to the ground. And if you have a light underside and you’re viewed from below, this can balance against an illuminated sky. But also, importantly, countershading can make an animal look flatter and this is the principle that we used to reconstruct the likely habitat that Sinosauropteryx was living in. That’s because different environments have different lighting and, therefore, you need different colour patterns in order to counterbalance this lighting.

Izzie - I read somewhere that also has a “Mask of Zorro”- like look. This sort of dark black banding across its eyes. How does that work?

Fiann - It does indeed. We could see the distinctive areas of pigmented feathers around the eye that would probably have formed a solid stripe that we refer to as a “bandit mask.” One of the likely functions of this, which is particularly seen in modern birds, is as another form of camouflage. This time actually masking the presence of the eye. Eyes are a really key cue for both predators and prey to avoid being eaten or to avoid being spotted so they can actually catch other animals.

But also having this dark stripe may also serve as a form of anti-glare device. A comparison for this is lots of sports people paint a dark stripe under their eye and this is to reduce the amount of sunlight reflecting back in, and the principle is the same for these anti-glare masks.

Izzie - Wow! You mentioned that a T.rex is a theropod so will this lead to further studies into a T.rex?

Fiann - Unfortunately, most of the fossils of that particular dinosaur are mostly skeletal; there’s very little in terms of soft tissue remains. Interestingly, there is a tyrannosauroid from the same formation as Sinosauropteryx which is an equally impressive and giant meat eater. This one was 9 metres long and that does have a covering of feathers on it. But, as far as I’m aware, no-one has yet looked at what it’s colour patterns might have been, so there’s a tantalising opportunity to look at what perhaps these giant theropods might have looked like.

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