Talking fossils with a digger :: Wessex Scene Online

Talking fossils with a digger

20th November 2007
Sarah Varley

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Most of us as children were fascinated with the concept of dinosaurs. Whilst this is something that most of us grow out of, there are some who dedicate their lives to them through the study of palaeontology.

I was privileged to interview one such person, Dr Stig Walsh of the Natural History Museum, London and asked him all that you wished to know about dinosaurs and more.

Why do you think dinosaurs have become imbedded in popular culture and do you think this image hinders people knowing the truth?

One reason why dinosaurs have become imbedded in popular culture is that they’re an extinct group of animals, many of which were very different from any animals that are on Earth today. We know a lot more about how dinosaurs moved, what they ate and so on than we did 100 years ago, but there is still so much we don’t know. That makes them incredibly interesting, because you have to use a lot of imagination to picture what a dinosaur might have been like. Of course, many (but not all) dinosaurs were large and fearsome, and that always helps!

On one hand the ‘extinct-ness’ of dinosaurs makes them a good subject to teach concepts of evolution, but on the other the widely-held view that dinosaurs are an evolutionary dead end shows a basic misunderstanding of what evolution is really about. Far from being weak animals destined to die out, dinosaurs were incredibly successful for over 165 million years, and were very well adapted to the world they evolved in.

Do you think that the changes in ideas come from technology or from new discoveries?

Obviously the most important changes come from new discoveries, although these days more and more of those discoveries come from the application of new technologies. In the late 1990s, for instance, there was a spate of new discoveries that provided new evidence about the transition from theropod dinosaurs to birds. Some of these were specimens of new species that had feathers, but were not actually birds. Others provided new evidence indicating the form of some internal organs, such as the Italian Scipionyx which provided new information about how dinosaurs might have respired.

The advance that technology has given us is that we are now able to look back at well known specimens, such as the London specimen of Archaeopteryx, and learn new things about them. Archaeopteryx remains important because it’s still the earliest example of a flying bird. Recently the specimen was reinvestigated here at the Natural History Museum using micro-CT scanning techniques, and from that analysis we learned that the brain of Archaeopteryx was far more ‘bird-like’ than previously thought.

How is the colour of a dinosaur worked out?

Well, there is a lot of guesswork there. The idea that some pigments might leave some kind of biomarker has been around for a while, but has proved difficult to test. Some exceptionally well preserved feather fossils do provide evidence of colour banding, although because the original colours are not actually preserved they really just give an idea of the former presence of patterning. The fact that some feathered dinosaurs might have had patterns and the realisation of how closely birds and dinosaurs are related, has led some people to imagine most dinosaurs as brightly coloured like many birds are today. In that respect the older ideas of dinosaurs always being drab greys and greens has pretty much gone out of the window. Of course, having bright colours could be a disadvantage if you want to creep up on your prey or stay hidden from something that might want to eat you, so the possibility that most species would have some form of camouflage is still very likely. However, many recent reconstructions have ‘borrowed’ from analogies with large living mammals such a stripped zebras. Although some dinosaurs such as hadrosaurs almost certainly moved in herds like zebra do today, I think we have to be very cautious about using modern mammals as analogues for extinct reptiles. Another consideration is whether dinosaurs would have actually been able to see colours. There isn’t much point in being brightly coloured, say for attracting a mate, if your opposite can’t see those colours. The colour reception capabilities of living birds and crocodiles might provide some kind of clue there, but ultimately that’s something we would only be able to say if we could dissect a dinosaur eye.

How do you work out what a dinosaur would have sensed?

This is where recent advances in non-destructive sensing have made big differences in dinosaur palaeontology. If we have a good uncrushed specimen of a skull, we can get a good idea of the development of certain senses by looking inside it using micro-CT analysis. This technique provides a series of x-ray slices through the skull from which we can reconstruct a 3D virtual version of the specimen and its internal structures. This reveals information about nerve pathways, size of the olfactory apparatus (for sense of smell), and relative development of parts of the brain that are involved in integration of sensory information, such as the optic lobes. These can then be compared to what we see in living animals, where we have better data on actual sensory capabilities. We are currently working on a new way to investigate hearing capability in dinosaurs using similar techniques here at the Natural History Museum. Since the best hearing range of most living animals covers the frequency range of their vocalisations, this line of research should also provide some idea of the sounds that these dinosaurs might have made.

In ‘untouched’ areas of the world, is it possible for dinosaurs to still exist?

Very unlikely – unfortunately! If there were sizable dinosaurs out there, I would have thought that with modern technology we probably would have seen them by now. Also, there would have to be enough of them to have a viable population in terms of gene pool. On the other hand, if the dinosaur was small, and perhaps living high in the upper canopy of a remote densely wooded region, I suppose it’s possible that something like that could have managed to escape detection. However, while we would like to imagine that any ‘living fossil’ would look like something we know from the Cretaceous period, I doubt this would be the case. Remember that it would have had at least 65 million years to evolve into something else better suited to the changing environment, and in that time it would surely have changed a great deal. If there were really anything out there I would have thought it would be more like some kind of bird-dinosaur hybrid adapted to jumping around in the trees, but I doubt it would be like anything we have seen in the fossil record. Anyway, dinosaurs do still exist; Trafalgar Square is full of them!

Do you think the loch ness monster could exist?

The current popular image of the Loch Ness Monster appears to be that of a plesiosaur, an extinct sea reptile with a long neck and paddle-like feet from the same time as the dinosaurs. In fact, plesiosaurs were not dinosaurs, but belonged to another group entirely. The picture of a plesiosaur swimming around in Loch Ness seems to have taken over from earlier ideas where the monster is depicted more like some kind of sea serpent, and I suspect this might switch might owe more to changes in popular culture than to sightings of a real plesiosaur. It’s cold in the loch, and it’s difficult to imagine how an reptile like that would be able to survive. If the ‘monster’ were a plesiosaur it would also have to come to the surface regularly to breath air, and probably also come ashore to breed. In that case I would have thought it would have been seen far more often than it has and, as I mentioned earlier, there has to be a viable breeding population for something like that to survive in the long term. The usual explanations of floating debris, released gas from the bottom of the loch, marine mammals such as seals and perhaps large fish seem more likely. That said, the loch has a history of sightings going back a very long way, so there must be something strange about the place. I doubt it has anything to do with extinct sea reptiles though!

With technology ever advancing, do you think in the future that the palaeontologist will be extinct?

Yes, the future doesn’t look too bright for palaeontologists! Much of the work that is done these days employs some form of computer modelling, and the future of palaeontology does seem to be digital. How dinosaurs walked, bit into their food and many other aspects of their lives, are all being investigated using computer modelling. We can now take a fossil encased in rock, image it using micro-CT, reconstruct the bones digitally, and then reconstruct the whole skeleton without ever having to chip a single piece of the rock away. This way there is no risk of damaging the fossil for future generations as there would be if we have to painstakingly chisel it out.

However, this is all fine only so long as you have good specimens. There will always be a need for people to go out into the kind of hostile environments that dinosaur fossils are usually found in and collect more specimens. We almost certainly know about only a very small fraction of the number of dinosaur species that existed, so there is a need to keep looking for new fossils all the time. To a certain degree palaeontologists can be divided into people who conduct theoretical work such as dinosaur relationships, biomechanics and so forth, and those who live to go out and dig up fossils. We need both kinds of scientists if we are to continue to find out more about how the world was before we as a species came on the scene. I’ve made the transition from the more fieldwork-oriented side of things to working with computer modelling, but at heart I will always be a digger.

I would like to thank Dr Walsh and all at the Natural History Museum for making this possible.