The wondrous world of dinosaurs continues to reveal ever more startling discoveries while keeping other secrets impossibly guarded.
Even if you aren’t interested in dinosaurs, it’s almost impossible not to absorb some information from the endless swirl of discoveries reported in the media, new documentaries and even movies (of bother greater and lesser quality). The public has become well aware now that birds evolved from, and are quite literally, dinosaurs, that many dinosaurs had feathers, many were active and potentially intelligent, looked after their eggs and young, might have lived in social groups. What you might have missed though is that more recently that palaeontologists have begun to work out what colours some of them were.
Even a few years ago I would have said that not only do we not know the colours of dinosaurs, but that we’ll never know. However, it has been discovered that tiny sub-cellular packages called melanosomes can be preserved in some exceptional fossils. In life, these contain various pigments that provide colour to skin and things like feathers, scales and fur in animals. Although the original pigments don’t survive fossilisation, by a quirk of evolutionary history, the shapes of various melanosomes are intimately tied to the pigments that they contain. In other words, you only need to see the shape of the package to know what colour was inside, and we can see their shapes most clearly with suitably powerful microscopes.
Thus the world of colour for dinosaurs (and indeed many other ancient animals) is being opened up. We know of ginger and white striped dinosaurs, those that were black but iridescent like magpies, and others that were dark with a splash of red on their heads. What was once unknowable has now become the norm, or at least the norm for a select few specimens where the preservation is such that the melanosomes are there. However, this fantastical discovery and development poses more questions than it solves.
First off, melanosomes are, rather annoyingly, only part of the story when it comes to colour. Exact shades of colour scan also come from the arrangements of melanosomes and this doesn’t preserve well, and other types of pigments don’t need melanosomes and so are much less likely to be preserved or even detected. So while we have a decent idea of the colours and patterns of a handful of species, it’s far from exact. Perhaps worse, we know of only single individuals in each case. While many animals do look very similar to one another within a species (it’s hard to pick out one crow over another) variation is often common too. Young animals can have different patterns and colours to adults, males and females can look very different, and when it comes to feathers birds can moult into camouflaged coats in winter and males might develop breeding colours for only a few months each year. On top of that (while rare) there are leucistic and albinistic animals that are unnaturally white in places and melanistic ones that are unusually dark compared to the rest of the species, and over time colours might evolve and change or simply vary regionally.
Taking a single dinosaur specimen as being representative of the whole species is likely to be misleading. But it’s also something that we can correct fairly easily—after all we have the techniques down and for some dinosaur species at least there are dozens or even hundreds of specimens that are well preserved enough to have their feathers and likely have melanosomes. It really should be just a matter of time and effort until we can begin to answer these questions and get a much better picture of the variations in these species and be able to tell males and females and determine what displays or camouflage colours they might have possessed. It is something we don’t yet know but it’s near enough a sure thing in the coming years.
It’s safe to say that other areas of dinosaur biology do remain frustratingly out of reach and might be beyond our grasp forever (though I used to say that about colours…). Fossilisation doesn’t occur at random—organisms need to be buried in sediments to ultimately become preserved and so places where there is rapid decay leaving nothing to be buried, or places where there is little deposition of mud, sand or soil and so no chance of a body being buried, produce very few fossils. For all that they teem with life, rainforests therefore are poor places to make fossils with bodies breaking down quickly and often little deposition from floods. Deserts, in contrast, are great on both counts—there are few animal scavengers and little decay from fungi or bacteria and the ever shifting sands have a good chance of burying bodies. That leaves us with the paradoxical issue that we know far more about the relatively sparse dinosaurian life of desserts where we have lots of fossils than we do about the doubtless teeming rainforests that don’t preserve them.
Similarly, volcanic island groups like Hawaii and the Galapagos are often places that are well isolated from continents and where stranded species can diversify into the most unusual and bizarre forms compared to their mainland representatives be it giant tortoises, flightless birds or marine iguanas. But they are also sites where there is not only little deposition but also massive risk of some tectonic activity that would sooner or later swallow or destroy the entire area. In other words, those places most likely to have the most bizarre and unusual animals are the ones least likely to leave any fossils at all.
No increase in palaeontological excavations or development of new techniques to scan and search for fossils can help us find things that simply don’t exist because they were never formed in the first place. That leaves us with perhaps the most known of unknowns, things we know that we don’t know and can’t ever be expected to change that.
For all the huge advances in science that have revealed ever more secrets about the dinosaurs with a depth and breadth that perhaps few appreciate, there are still whole areas where we know nothing or have only just begun to explore them. The good news is that that future of dinosaur science is bright, and at least on occasion, with ginger stripes.
David Hone is a palaeontologist and senior lecturer at Queen Mary University of London. He has written about dinosaurs for leading publications such as National Geographic, The Guardian, The Telegraph and HuffPost. His books include The Tyrannosaur Chronicles: The Biology of the Tyrant Dinosaurs.