Colouring in the dinosaurs
A series of clever studies has painted prehistoric worlds with unexpected colour and it may yet start to fill them with sound, too.
Ninety-four million years ago a vast inland sea runs the length of North America from the Arctic Ocean to the Gulf of Mexico. Its waters are an effective barrier that divides the landmasses of Laramidia to the west and Appalachia to the east, and both are home to a diverse and unique fauna of early birds and feathered theropods. Predatory reptiles stalk the waterways too, and among their number is a lone ichthyosaur of a kind known as Platypterygius. Shaped something like a fat dolphin, this 7-metre-long air breather is highly adapted to life in the oceans. She has massive saucer-shaped eyes that allow her to pick up traces of light in the depths where she hunts for squid, and she gives birth to live young in the water, so does not need to venture onto land to lay eggs as turtles and crocodiles do.
Hunting deep-sea squid is not the only similarity she has with modern sperm whales. Like them, she is also a uniform jet black, which helps camouflage her in the inky depths and absorb as much warmth from the sun as possible when she comes to the surface for air. Normally she spends as little time near the surface as she can, as this is where she is most vulnerable to larger predators. Today, though, she is lingering, as she is about to give birth.
This Platypterygius is among the last of her kind. Ichthyosaurs have been enormously successful for 150 million years, but they have been on the decline for tens of millions of years and now they face a new threat in the form of larger marine reptiles known as mosasaurs. Little does she know it in her current agitated state, but a 15-metre-long mosasaur has been circling in the waters beneath her for some time now. Part of a group that also gave rise to monitor lizards and snakes, mosasaurs have elongate bodies, four flippers and long tails with broad flukes on the end. This predator is darkly pigmented on its upper side and lightly pigmented on its underside, making it difficult to spot from both above and below. Before the Platypterygius has the chance to give birth, the mosasaur shoots up from the depths, violently clamping her within its wide jaws, and bringing nearer to its end the long tenure of ichthyosaurs in these prehistoric waterways.
This scenario is fanciful, but thanks to a study published in early 2014 by researchers led by Johan Lindgren at Lund University in Sweden, we do now have some good clues as to the colour of both ichthyosaurs and mosasaurs. The research was the first to reveal the colour of extinct marine creatures and it followed on from a string of papers in recent years that had revealed the colours of prehistoric birds and feathered dinosaurs by mapping pigment-bearing structures within fossilised skin and feathers.
‘This is fantastic!’ Lindgren told reporters. ‘When I started studying at Lund University in 1993 … it was unthinkable that we would ever find biological remains from animals that have been extinct for many millions of years, but now we are there and I am proud to be a part of it.’
In the 1990s, any book, teacher or scientist would have told you we’d never be able to tell anything about the colour of extinct animals such as dinosaurs. The best we could ever do was make comparisons with living creatures, and often reptiles were deemed to be the best analogies for dinosaurs. Most dinosaurs were painted in similar shades to crocodiles or monitor lizards, in greys, greens and browns. It seems puzzling now when you think about it. Birds and mammals – from flamingos, peacocks, parrots and cassowaries to tigers, zebras, baboons and red pandas – are a large range of vibrant shades and hues, and even many lizards – from chameleons to anoles – have striking patterns of colouration.
Since the discovery of feathered dinosaurs in 1996, the assumption had been that they might have had some of the same vast variation in plumage that birds do today, but few people believed such a thing would ever be confirmed.
That was until January 2010, when a remarkable paper in Nature suggested that Sinosauropteryx had sported ginger and white stripes around its tail, perhaps something like the pattern found on ring-tailed lemurs today. ‘Oh no, it’s Ginger-saurus! For first time scientists uncover colour of dinosaur and it was … a red-head’ was one headline, in the United Kingdom’s Daily Mail newspaper, which went on to say: ‘As if its short stature and ugly feathers weren’t enough to give it an inferiority complex, one of the world’s best preserved dinosaurs now turns out to have been ginger.’ A jaunty illustration painted by Chuang Zhao and Lida Xing, and released when the discovery was announced, depicts two cheeky-looking, ginger-fluffed Sinosauropteryx. Their heads are thrown back, and each is cavorting on a single leg with arms flung wide to impress or perhaps intimidate the other.
The research study, from scientists in China and the United Kingdom, also revealed black, white and orange–brown colouration on the early bird Confuciusornis. Similar work has now revealed the feather colours of Archaeopteryx and of the four-winged flyers Anchiornis and Microraptor. These discoveries have opened up a novel field of research, allowing palaeontologists to delve back more than 100 million years and probe the lives of dinosaurs and early birds.
‘Feathers are key to the success of birds and we can now dissect their evolutionary history in detail’, Mike Benton, one of the experts behind the work, told reporters. ‘The simplest feathers, in dinosaurs such as Sinosauropteryx, were only present over limited parts of its body – for example, as a crest down the midline of the back and round the tail – and so they would have had only a limited function in thermoregulation [maintaining body temperature].’
His team therefore suggested that feathers arose initially for colourful display purposes and only later were co-opted for insulation and eventually flight. The idea that display and communication were the initial functions of feathers is interesting because most experts believed the first feathers were for insulation. If colourful feathers evolved for display, they might have played a much more integral role in the success, evolution and diversification of dinosaurs than has been supposed.
Uncovering the colour of feathers
How on earth can you find out anything about the colour of feathers from the fossil record? I admit to having been baffled by this when stories of the orange plumage of Sinosauropteryx first broke in 2010. To answer that question, we have to look into a little of the science of how animals make colour in the first place.
Pigmentation
The pigment that gives our hair and skin colour is called melanin (from the Greek melanos, meaning ‘dark’) – it’s the same substance that is produced when we sunbathe, making us look tanned. Like all pigments, melanin works by absorbing some wavelengths of light and reflecting others to produce specific colours. Inside hair and feathers, it’s wrapped in tiny packages known as melanosomes, which create shades of black, grey, orange and brown. When I say tiny, I mean really tiny; most are 200–600 nanometres (millionths of a millimetre) across – 200 of them can fit across a human hair. Though diminutive, they are incredibly tough and actually form part of the strong protein structure of hair and feathers. They are so tough, in fact, that they can survive in fossils for hundreds of millions of years.
According to Mike Benton, until very recently, people just wouldn’t have believed melanin would get preserved. Even more so after a series of high-profile failed efforts to recover DNA from dinosaur bones in the 1990s made people extremely cautious about attempting to retrieve proteins or any other organic molecules from fossils. But it turns out that melanin is a very tough chemical, and part of its function in hair and feathers is to make them strong. ‘This is why, when you get older, and like me your hair gets grey, it actually gets weaker’, Benton explains. In any case, he says, ‘we’re not detecting the presence of melanin by chemical means in fossils, we’re doing it by physical means. It’s because it’s encapsulated in these melanosomes’. Keratin – the protein from which hair and feathers are made – is a plasticky kind of substance, so in order for the melanin to get into it, it needs to be encapsulated.
Jakob Vinther, a molecular palaeobiologist based in Benton’s department at the University of Bristol, was the mastermind behind the colour-identification technique, in which different pigments, such as red, brown, buff, grey and black, are detected simply by looking at the shape of melanosomes in the fossils using a powerful electron microscope. In modern birds, melanosomes that result in different feather colours are different shapes: while sausage-shaped eumelanosomes contain the pigment eumelanin and create black plumage, the spherical phaeomelanosomes contain phaeomelanin, which creates orange plumage. These shapes are what Vinther first searched for in fossils of the early bird Confuciusornis while he was still a graduate student at Yale University.
In mammals, pigment is the common way to produce and display a colour. Pigments in both plants and animals work by reflecting and absorbing different wavelengths of light. White reflects all wavelengths of light, black absorbs all wavelengths, and colours in between selectively absorb some wavelengths but not others. Chlorophyll, which makes plants green, for example, absorbs all red light but reflects green; anthocyanins, found in red leaves, absorb green and blue light but reflect red and yellow.
In 2013, a study that simulated the fossilisation process cast some doubts over the reconstructions of dinosaur colour from melanosomes. Maria McNamara, a researcher then in the same department as Vinther and Benton at Bristol University, attempted to mimic fossilisation by subjecting modern feathers to great heats and pressures akin to those they might experience underground in the earth’s crust. ‘A brief spell in an autoclave can reasonably simulate the effects of temperature and pressure during burial over millions of years’, she told Nature. Her research indicated that melanosomes shrink during fossilisation, which might affect their shape and therefore the reconstructions of their colour. Vinther’s response was that the melanosomes shrank almost equally in several dimensions, so his reconstructions of colour shouldn’t be affected. Only time and more research will tell whether the fantastic new visions of coloured dinosaurs are accurate or not.
Iridescence
Birds, insects and fish, however, have another trick besides pigment up their sleeve, and it allows them to be decorated in a much brighter, brasher range of gaudy hues than we comparatively drab mammals could ever hope for. Iridescence is so-called structural colour, which occurs when light bounces off physical features in the surface of feathers or scales and is split into different colours, in much the same way a prism splits white light into its constituent colours. Some birds – parrots with green plumage, for example – use a mixture of both yellow pigments and blue iridescence to create their colour.
The structural features that manipulate the light vary, but include wafer-thin stacks of translucent organic material that interferes with and reflects light. These films, made of chitin in insects, can reflect and amplify light of one particular colour or wavelength over and above others. This is how iridescent or metallic hues are produced, such as those that adorn the feathers of birds of paradise and peacocks, butterfly wings and a whole spectrum of beetles. Sir Isaac Newton, who shed much light on optics and refraction, was the first to reveal that minute layered structures were the cause of colour in peacock feathers.
In 2003 I first learnt about the possibility of structural colours persisting in fossils when I wrote a story for National Geographic’s website about a 50-million-year-old beetle fossil that still had a brilliant-blue iridescent sheen – in this case, the fossil was so incredibly well preserved that the ‘multilayer reflector’ that created the colour in the surface of its exoskeleton was still intact. At the time the fossil was the oldest known to retain any bright colour, and it may still hold that record. Oxford University’s Andrew Parker said then that we might one day be able to study the physical features of dinosaur fossils to predict what colours their feathers might have been. It seemed like science fiction to me, so it was a thrill to see the idea come to fruition just seven years later.
Vinther, Benton and their co-workers at Bristol University have been able to find evidence of these structural iridescent colours in fossilised dinosaur feathers by looking at the density, orientation and stacking of the melanosomes. In some cases, melanosomes act to produce colour in two ways: through the pigments wrapped up inside them, but also through their stacking and organisation, which interferes with and manipulates the light that hits them.
Sinosauropteryx was just the start, and now a series of compelling papers has detailed the colours of Archaeopteryx, Anchiornis and Microraptor. National Geographic described Anchiornis as having ‘looked something like a woodpecker the size of a chicken, with black-and-white spangled wings and a rusty red crown’. The team behind that discovery, including Yale University feather expert Richard Prum, analysed the colour on 29 different regions of the animals’ body, giving them a largely complete picture of the overall plumage pattern. Archaeopteryx would have been black, while a 2012 study of 130-million-year-old Microraptor revealed it would likely have had dark-blue to black plumage with an iridescent sheen – perhaps similar to a crow or raven.
‘Modern birds use their feathers for many different things, ranging from flight to thermoregulation to mate-attracting displays’, Prum’s co-author Matt Shawkey, from the University of Akron in Ohio, told reporters. ‘Iridescence is widespread in modern birds and is frequently used in displays. Our evidence that Microraptor was largely iridescent thus suggests that feathers were important for display even relatively early in their evolution.’
A third method is being developed that actually looks for remaining chemical traces of pigments themselves, based on the fact that when eumelanin forms it binds up copper and so in fossils leaves telltale traces of the metal behind. ‘There has been proposed a method to look at pigments using metal mapping of copper’, Vinther says, but it would only be useful for detecting black melanin, and – because copper levels fall as the melanin degrades – it would also be prone to error from other sources of copper in the deposits. It remains to be seen how effective this method will be, but it’s exciting in prospect.
The value of colour
The fairy wrens of Australia and New Guinea are delightful little songbirds, some of which have brilliant blue and iridescent plumage. Recent studies have also shown that male fairy wrens of some species have patches of feathers that reflect ultraviolet (UV) light. This is invisible to us, but appears as another layer of colour to female wrens. While humans have three types of colour-detecting rod cells in their eyes – red, blue and green – birds have a fourth, which detects UV light. This means they see the world in a much more complex palette of colours than we can. This illustrates just how important colour is to these animals, and that the ability to see a wide range of bright colours may have been spurred on by colourful plumage that evolved for display purposes in their dinosaur ancestors.
It would be no surprise to find that dinosaurs were as varied and colourful as birds, given they most likely shared the full colour vision of birds. While some mammals are colourful, most tend to be fairly drab, in greys and browns and shades of black and white. This is because, aside from a handful of species (including chimps, orangutans, baboons and humans), they don’t see in colour, instead visualising the world in black and white. Mammals also have more of a need to be camouflaged than birds, because they often live on the ground and find it more difficult to flee from predators.
‘Birds are brilliantly coloured because they do see in colour, and it’s likely that because birds are a kind of dinosaur, the extinct dinosaurs also saw in bright, vivid colour’, says Mark Norell. These colours might have helped them recognise other members of their own species, camouflaged them, or been used for defence to dissuade other animals from attacking them (in the same way that some poisonous frogs are thought to use bright colours as a signal that says, ‘Don’t eat me, I’ll make you sick’). Of course, in living birds, some of the most brightly coloured are the males of those species that use colour to woo and court females, such as peacocks and birds of paradise.
Dinosaurs evolved a great array of ornamentation – including crests, frills, horns and spikes – to attract mates, warn off rivals and otherwise communicate. This surely means they used feathers for the same purpose, just as many brightly coloured birds do today. ‘Once dinosaurs had acquired feathers for insulation, what could be more natural than to adapt them into display structures?’ asks Phil Currie. ‘They are lightweight, strong, colourful, and can be shed and replaced.’
Could it even be that the success, diversity and longevity of the dinosaur family is attributable to the bright colours the evolution of feathers afforded them? In combination, the variations in colour and structure can be a powerful tool for creating the differences between isolated populations that allow new species to form. The formation of new species is dependent on there being some sort of barrier to individuals of different populations mating. Feathers are a ‘perfect structure to provide such a platform’, says Xing Xu.
Though at this stage he says it’s just a ‘crazy idea’, he believes there may even be a way to test the link between feathers and evolutionary success in a group of animals. The first step is to confirm whether the different kinds of feather-, quill- and fluff-like structures seen in fossils of pterosaurs and dinosaurs (such as Sinosauropteryx, Caudipteryx, Beipiaosaurus, Tianyulong and Psittacosaurus) all share a single evolutionary root, or if they evolved in separate instances. The next step would be to try to reconstruct feather colours and then compare the diversity of brightly coloured groups of dinosaurs and birds with that of groups without such a range of brightly coloured feathers.
Sounds of prehistory
Sitting on my balcony in Sydney early some mornings I am treated to the awesomely loud guttural screeching of a noisy flock of sulphur-crested cockatoos. This garrulous and gregarious group congregates in the trees and on neighbouring balconies. The harsh caws of cockatoos are not pretty, and when I first moved to Australia, I was struck by the contrast to the tuneful twittering of British songbirds. In fact, I’ve often joked that cockatoos and other noisy Australian birds sound like dinosaurs or pterosaurs – the grating noises they make seem far more fitting for such fierce and imposing animals. But the truth is we don’t know very much at all about the noises dinosaurs made.
Until recently, sound was another aspect of dinosaur lives that experts thought we would never know anything about. But a few fascinating anecdotes give us some insight into dinosaur vocalisations. Most birds can make calls today – in fact, birds are the most habitually noisy and melodic members of the animal kingdom – so it’s reasonable to assume their dinosaur ancestors employed sound to communicate too.
John Long says we need to take a step back and think about what might have been physiologically possible in dinosaurs. He tells the story of an occasion several years ago when he was producing sound for a clip of dinosaurs to be shown at Museum Victoria in Melbourne. ‘The guy at the sound factory immediately mixed a crocodile sound with a lion roaring and came up with this monster-type roar, and he thought that was probably what a Tyrannosaurus sounded like’, he says. ‘And I said: “Nope. You’re completely wrong. These things don’t have vocal cords.” Mammals are the only group that have vocal cords.’
Instead, he says, birds produce sounds by expelling air out of their windpipe and modifying its shape with their mouth, and they sometimes use their tongue to warble too. The sounds of dinosaurs would have been more like those of birds and certainly not like the kind of ‘throaty growls’ mammals produce. ‘The best way to hypothesise about the sounds dinosaurs made is to know the anatomy of their throat, mouth and lungs’, Long says. And you never know, with all the fossil dinosaurs coming out of China that have incredibly preserved soft tissues, we may yet get a totally unexpected clue about dinosaur vocalisations.
Jack Horner, palaeontological advisor to Steven Spielberg for the Jurassic Park films, has looked to the sounds of birds when creating appropriate soundtracks for museum displays. He agrees that the best approximation we can make for dinosaurs is to take bird vocalisations and slow them down to make them more like the deeper notes that would come from much larger animals. (In case you’re wondering, the sounds used in the 1993 film were a whole bunch of manipulated animals noises, from dogs yapping, geese hissing and randy turtles barking, to horses squealing, donkeys yodelling and swans hooting.)
Others scientists have found more direct evidence of the kinds of sounds dinosaurs made. In the early 1980s, David Weishampel, an anatomist at Johns Hopkins University in Baltimore, Maryland, tested an idea that duck-billed hadrosaurs used head crests to make deep vocalisations for communication within herds and family groups, similar to elephants. Parasaurolophus were 2.5-tonne plant eaters with large, tubular bony crests that swept back for a metre or more beyond their skulls. The purpose of the crest has been the subject of much debate since the discovery of the species in 1922. Was it used for display, for defence, for sound – or for all three? One strange theory even suggests the crests were used as snorkels.
Weishampel went as far as creating a plastic replica of the crest, which he fitted with a trumpet mouthpiece and played like a wind instrument to simulate at least partially the sounds the animals made. You can find clips of him doing this online, and to my ears it sounds very similar to a didjeridu. He published a paper on this research, arguing that the crest was a good resonator for making powerful low-pitched noises.
In 1996 scientists used supercomputers at the Sandia National Laboratory in Albuquerque, New Mexico (which more typically conducts research into new weapons), to create detailed reconstructions of the shape of Parasaurolophus crests and further simulate the kinds of noises that could have been made by forcing air through them. As you would expect, the study revealed that the basic pitch of the note produced was set by the length of the tube. But it also found that the crest had a far more complicated internal structure than had been previously supposed, hinting that the animals might have been able to make a complex and subtle repertoire of calls. Experts at the lab argued that the sound would have been bird-like and might have been used for creating songs as a form of communication.
That research gave some sense of the pitch of vocalisations, showing that young duck-billed dinosaurs would have made higher pitched sounds, and that big adults with large crests on their head would have made deep infrasound bass notes inaudible to human ears. ‘Fossil records of the large bones in the dinosaurs’ ears compared with corresponding bones in human ears suggest they were able to hear lower frequencies than humans’, Carl Diegert of the Sandia lab told reporters.
According to Stephen Brusatte, at the University of Edinburgh in the United Kingdom, another avenue to understanding dinosaur vocalisations has been to use CT scans to look inside the fossils of dinosaur skulls and see the shape of the inner ear and the parts of the brain responsible for processing information from the ear. By comparing the shape of the ears of dinosaurs to those of living animals, researchers have been able to show that animals such as T. rex were certainly able to hear very deep sounds.
More recent research has shown that three other hadrosaurs – Lambeosaurus, Corythosaurus and Hypacrosaurus – were also likely to have made deep-pitched calls to communicate with one another, and certainly had ears that would have been able to pick up these low notes.
Phil Senter at Fayetteville State University in North Carolina has studied the evolution of sounds throughout the history of life on earth and shown that birds, and their close relatives crocodiles, make sounds in quite different ways. Birds have a specialised sound-producing structure called a syrinx, which is found on the trachea near the branched opening to the lungs. Crocodiles, on the other hand, use their larynx to make sounds (the vocal cords of mammals are infoldings of membranes across the larynx). The fact that birds and crocodiles evolved such different structures for producing sound perhaps suggests that the common ancestor of these animals didn’t produce sounds at all, Senter concluded. His analysis also suggested that not all fossil birds possessed a syrinx, which implies it’s an innovation that appeared after birds evolved and therefore was probably not possessed by their dinosaur ancestors.
‘The lack of evidence of a syrinx … will, no doubt, disappoint fans of roaring movie dinosaurs’, Senter wrote in a 2008 paper. ‘However, lack of ability to vocalise does not necessarily mean that such animals were silent altogether.’ Modern reptiles often communicate with one another using non-vocal means of producing sounds, he says. These include hissing, clapping jaws together, grinding lower jaws against upper jaws, rubbing scales together, and using materials in the environment. In addition to their songs, birds also make non-vocal sounds by hissing, bill clapping, stamping and wing beating.
Dinosaurs with feathered wings may therefore have flapped to create noisy displays as some birds do. Even more intriguing is the suggestion from some scientists that the very long tails of sauropods, such as Diplodocus, might have been used to create a loud noise like the crack of a whip, perhaps to scare off predators. Cracking a whip creates a shock wave, or sonic boom, that is the result of the tapered tip momentarily exceeding the speed of sound. Research by Phil Currie and computer scientist Nathan Myhrvold predicted that when the long tapering tails of sauropods were flicked from side to side, a wave of energy could propagate along them, gaining momentum and propelling the tip to velocities higher than 1200 kilometres per hour. This is much faster than the speed of sound (and some experts have pointed out this sounds painfully implausible).
We may never know for sure the kinds of sounds dinosaurs made, but by looking at birds and crocodiles we can make some educated guesses. One thing seems fairly certain, though, and that’s that dinosaurs didn’t produce the kinds of bellows and roars depicted to dramatic and terrifying effect in movies.
Recreating the sounds and appearance of dinosaurs is an important endeavour. And with all the new discoveries of such well- preserved Chinese dinosaurs with largely complete skeletons, and impressions of soft tissues and feathers, palaeontological illustrators have more to work with than ever before. Information about the colour of feathers is just the latest piece of the puzzle that allows dinosaurs to be reconstructed with previously unexpected accuracy.
The purpose of palaeontology is largely a curiosity exercise, and without artists working alongside them, it’s very difficult for scientists to bring fascinating discoveries to wider public attention. Illustrations of feathered dinosaurs can be great works of art in their own right, but they are also one of the most important tools for communicating new discoveries.
It’s difficult for the average person to look at a skeleton, or fossil fragments of one, and form an idea of how that animal might have looked in life. If it’s an animal we’re familiar with, such as a horse or a human, then we already have something to go on, but many dinosaurs and other prehistoric animals are ‘wonderfully alien’, says Dave Hone, a palaeontologist and blogger at Queen Mary, University of London. ‘Illustrations can have huge power to show the scale, size and proportions of dinosaurs, restore missing parts, and give things some real weight and realness that a fossil cannot. That gives people a much better understanding or impression of the issues, and can of course help promote palaeontology generally and encourage interest and support.’
Illustrations of dinosaurs seem so ubiquitous that it’s hard to imagine all the work that goes in to them, but rebuilding a living animal from a scattering of fragments requires specialised knowledge of palaeontology and a careful collaboration between artist and scientist. The fact that the first known dinosaurs were initially reconstructed as low-slung creatures with legs out to the sides in a sprawling gait goes to show what a challenge it is to understand extinct anatomy.
‘The challenge for the illustrators is to balance the artistic merits of a piece with scientific rigour’, says Hone. ‘In terms of getting the actual science bit right, there are tons of details: restoring the missing bones; getting the proportions right of all the bones and parts; getting the angles right of the major joints; getting the size and positions of all the muscles right, and making sure they’re slack in some places, but bulging and tight in others; creating the details of the nostrils, ears and eyes, not to mention skin scales and feathers. Then there’s the environment … Hence good illustrators take a lot of time, and they know a lot of palaeontology and anatomy, as well as being good artists.’
Illustrating all the new feathered dinosaurs of China has been an especially important task, since the appearance of carnivorous theropods in our imaginations has gone through a revolution from crocodile- or lizard-like creatures to lively animals of an avian persuasion, often sporting brightly coloured plumage.
Luis Rey, one of the world’s top dinosaur illustrators, says the main challenge has been to break the comfortable and pervading view of the mass icon. ‘Many of us grew up with the image of giant beautiful monsters that became obsolete and died out’, he says. ‘However, from the 1970s onward we needed to look at them as once-living animals, and also look at their living relatives.’
The renewed study of dinosaur ecology, anatomy, metabolism and posture was met with scepticism at first, as was the later idea that they were the close relatives of birds, he says. ‘The last barrier was broken when the first hard evidence of dinosaurs with feathers was found [in 1996]. After that, the icons started to look like lizards with feathery coats, and that also had to be overcome.’
First and foremost, Rey’s inspiration for illustration comes from nature. His ideas take into account the fact that animals today have similar patterns for adaptation to natural environments. He also bears in mind that given dinosaurs had colour vision (as birds and reptiles do), they would probably have used skin patterns and colours to blend in, threaten other animals or attract attention. ‘Dinosaurs had also feathers, crests and other display items’, he says. ‘Therefore you can expect that the Mesozoic was indeed a colourful period in life. We are merely beginning to scratch the surface thanks to “Rosetta stone” deposits like the Yixian [Formation of Liaoning] in China.’
Highly skilled palaeoartists such as Luis Rey, Lida Xing, Julius Csotonyi, Gregory S Paul, Peter Schouten, Jan Sovak and Brian Choo have been responsible for bringing feathered dinosaurs to life (as the image section shows). Lida Xing has painted wonderful scenes for Australian Geographic of Aussie dinosaurs such as Minmi, Australovenator and Diamantinasaurus. Most excitingly, he created the first ever illustrations of what may be an Aussie tyrannosaur (see image section), as well as a series of seven illustrations of giant marine reptiles, some of which had never been reconstructed before. In these cases we were getting the first exciting glimpse of species that had previously been known only from a smattering of bone fragments.
Research into the sounds and colours of dinosaurs may help artists and filmmakers enliven them in our minds, but what if we could go one step further? Popular culture has often played with the idea of bringing a dinosaur back from the dead. This thrilling idea has seemed nothing more than fiction, but an audacious project conceived in the United States is now looking to the DNA of dinosaurs buried deep within modern birds as a means of attempting just such a thing. Philosophical and ethical issues abound, but reawakening – in a living animal – dinosaur traits that have been asleep for 66 million years would surely be the ultimate tool for stirring the human imagination.