Wednesday, August 14, 2013

How Do Creationists Know What Dinosaurs Looked Like?

While watching a video of the Creationist Museum in Kentucky, with its impressively-detailed animatronic full-scale dinosaur models, I was struck by the thought: how do creationists know what dinosaurs looked like? I mean: there are these moving, snarling model dinosaurs in an institution which has elevated pseudoscience to the dubious level of a theme park attraction, and whose staff (at least, in the various interviews which I have seen them give) appear to have a near-pathological disdain for the scientific method. So how do creationists know what dinosaurs looked like?

Using a line grid to map a fossil site at the Bay of Fundy, Canada
Time on a museum field trip is a precious commodity. It has to be exploited to the maximum, and working hours need to be methodical and calculated. I recall on one field trip getting up at five in the morning, every morning. And weekends simply passed unnoticed. A field trip can by turns be fun, exciting, and tedious – but it is still hard work. How many excursions into the field did it take, over succeeding decades of time, and spanning many, many individual careers, for palaeontologists to reconstruct the dinosaurs’ world? And where did those scientists go to? From the Montana Badlands to arid Outer Mongolia, from Patagonia to Alaska’s North Slope, the destinations of such field trips usually demand  lobbying for the necessary funding, and in the cases involving some far-flung destination, as often as not some deft bureaucratic navigation through the acquiring of visas, permits, and other assorted red tape.

Freeing a fossil from its rock matrix
Safely back on base, the conservation work begins: the painstaking release from its matrix, with small hand-held power drill and sable brush, of some fragile fossil, perhaps over a series of weeks or even months, and the publishing of any findings, as well as the report to the board of the museum in question to justify the funds which have been sunk into both the field work and the subsequent in-museum research and restoration time. More often than not, a fossil will not be found in any great degree of articulation: it usually will be both disjointed and incomplete, or even scattered over a wide area. Maybe the skull is missing – or conversely, maybe the skull is the only part found. So what would the missing parts have looked like? And what does the surrounding fossil environment tell us about the fossil itself? Was it buried in a flash flood, or by a collapsed sand dune? Was it a victim of predation, or was it a predator fallen victim to another of its species? What might the fossil bones tell us about that individual dinosaur’s pathologies – its injuries and diseases – which it suffered in life?

Give this grid-defined fossil site map to a creationist, and tell them to restore the dinosaur(s) visible here, using only this map for reference. Click on the image to see the scale of the task!
These are just several of the many questions facing a palaeontologist when confronting a jumbled scattering of disarticulated fossil bones in a field location. And that scattering of bones might be from one individual or from several – and even then they might not be of the same species. Only later will someone like myself be brought in to flesh out the painstakingly restored bones as a life reconstruction, always recognising that there are lines between applied knowledge, reasonable assumption, and artistic licence. Applied knowledge would include such factors as the attachment points of muscles, which usually can be seen on bone as areas of rough pitted striations. Reasonable assumption could be the stance in which the animal is shown, which can be enhanced by the applied knowledge of the way in which the skeleton would have been articulated in life. And artistic licence would typically involve skin colour and patterns, which generally are speculative. But always when creating such a life reconstruction, I am aware of the untold research time of career scientists, both in the field and in the museum, behind what I am doing.

My life reconstruction of the head of a dryosaur: a mix of applied knowledge, reasonable assumption and artistic licence, and drawn with an awareness of the differences between these three factors.

So how do creationists know what dinosaurs looked like? They do not commit their time and *resources to the rigours of museum field work. They do not spend their working lives painstakingly piecing together the herculean puzzles of fossil bones tackled by professional palaeontologists. There is only one answer possible: they have acquired this knowledge by climbing over the backs of the very scientists whom they so openly despise. And the reason why creationists are able to include in their institution those crowd-pulling animatronic dinosaurs is because career scientists of all persuasions, philosophies and beliefs, but all of whom endorse evolutionary theory and geological time, have committed their working lives both to finding and restoring those jumbled scatterings of fossil bones.

Top image: Earthquake Dinosaurs. Second image: Australian Geographic, photo: Kara Murphy. Third image: Barnum-Brown Howe Quarry dinosaur bones map from Wikimedia Commons. Fourth image: original artwork © Hawkwood.

* Please don't mention the name 'Buddy Davis' to me. A scientist might play country music, but a country music singer does not a scientist make. Mr. Davis also considers himself to be a reconstructional artist of matters dinosaurean. Looking at his work is a chilling reminder of what can happen when reconstructional art is unsupervised by qualified professionals. So.. the Creation Museum organizes a 'field trip' to dinosaur country in Montana led by... Mr. Davis? Oh, spare me...

Monday, October 29, 2012

Ancient Wings

I began my previous post by speculating about keeping a pet dinosaur. It was only a short while after I posted it, however, before I realised that I already had done just that! When I lived in Australia I had a pet canary which, in a blaze of originality, I had christened Birdie. Despite his modest size, Birdie was as much of a dinosaur as any other bird alive today, for science now recognises no distinction. In fact, as far as scientific classification goes, there are no birds – just dinosaurs which are classified either as non-avian (all those dinosaurs which we traditionally think of as being just that) and avian (all dinosaurs which we now think of as birds). Or to put it another way: dinosaurs never actually became extinct – they just became birds.

In 1861, just two short years after Charles Darwin shook the prevailing world view with his publication On the Origin of Species, and as if on cue to reinforce all which he claimed, the fossil of a single perfect feather was found in a limestone quarry in Bavaria. The fossil beds were one hundred and fifty million years old, placing the bird within the Late Jurassic. But did the feather really belong to a bird? Nine subsequent finds from the same location (the specimen in the Berlin Museum, above) revealed remarkably preserved fossils of an animal no larger than a raven, which shared the characteristics of both dinosaurs and birds. The feathered wings and tail were clearly visible, but in place of a bird’s beak, this creature had a jawfull of sharp carnivore teeth (the claws and skull of the recently discovered 'Thermopolis' specimen, below).

And not only that: the sternum (breast bone), which in flying birds is massively developed as a distinctive  keel shape to anchor the strong pectoral muscles needed for the wing downstroke in flight, was comparatively small and flat. And this animal had a long bony tail, gastralia (belly ribs), and functional grasping claws on its forelimbs – all typical characteristics of raptorial dinosaurs – but not of birds. Science named the animal Archaeopteryx lithographicaArchaeopteryx meaning ‘Ancient Wing’, and lithographica, because the quality limestone quarried at the site was used in the then-prevailing lithographic printing process.

Whether we regard Archaeopteryx as a bird or as a dinosaur has very much to do with our own classifying mindset. In reality, the fluid evolutionary mechanisms of nature do not express themselves in these clear-cut terms. It is both and neither – although for science it is a dinosaur with flight capabilities. But how well could it fly, if at all? The clearly-defined wings of the fossil powerfully suggest the idea, but the skeletal anatomy speaks against it. With a good head wind it might have managed a brief glide, although probably not much more than this. When I made a rough sketch of the overall body shape (above) what became clear was that this animal was a good runner – another trait of its raptorial dinosaur connections. In fact, one fossil of Archaeopteryx which was preserved without feather impressions was for decades thought to be a fossil of the small carnivorous dinosaur Compsognathus, whose habitat Archaeopteryx shared.

Earlier this year, and just over a century and a half after its first discovery, the fossil of that compelling single feather (above, with below it, my drawing of a chicken feather for comparison) was re-examined. Using a powerful electron scanning microscope, the parts of the cells which produced pigmentation, known as melanosomes, were isolated and determined to be black. Black melanosomes would serve to strengthen the feather’s structure, making it more durable, and so aid any attempted flight. The discovery had its consequences for me personally, because some ten years earlier I had painted this ‘portrait’ of Archaeopteryx (below), and with the information which I then had to work with, my choice of colours was wholly speculative.

But in my reconstructional art I passionately believe that, as in science, I have to follow wherever the available evidence takes me. With this new evidence now to hand, a rethink was clearly in order. I scanned in my original acrylic painting and digitally repainted the colours (below) to reflect these latest findings. And interestingly – and contrary to my own expectations – I find this second updated version more convincing.

At the moment, we do not know whether Archaeopteryx was an overall black, or whether this applied only to the flight feathers, of which the single feather is one. But now I find that I rather enjoy the idea of a black Archaeopteryx, with its raven-dark wings catching a flash of iridescence in the sunlight as, hesitantly and experimentally on some far Jurassic Kitty Hawk beach, it took advantage of a strong onshore breeze and raised itself for a few momentous seconds above the sands.

Ryan M. Carney, Jakob Vinther, Matthew D. Shawkey, Liliana D'Alba & Jörg Ackermann:
New evidence on the colour and nature of the isolated Archaeopteryx feather
Published as Article #637 in Nature Communications, 24 January 2012

In his chapter on theropods in The Complete Dinosaur, edited by James O. Farlow and M. K. Brett-Surman, Philip J. Currie mentions that dinosaurs and birds share more than one hundred and twenty common characters in their anatomical features, and he concludes that '..the only character to define birds (from dinosaurs) is their ability to fly.' I would also add that all theropod dinosaurs and birds share the distinctive character of pneumatic (hollow) bones, and that it's worth remembering that feathers are simply modified reptile scales.

Tuesday, October 2, 2012

My Pet Dinosaur

Were I allowed by some chance of time and nature - and my tolerant wife - to keep a pet dinosaur, then this particular dinosaur would be high in the running for my choice. I have, however, no name to offer it, because science has not given it one. The reason for this is that it is known only by its tracks: not a single fossilized bone has been discovered which can be associated with these tracks.

Such fossils are known as trace fossils, because they are the indirect traces which an organism has left behind, rather than being actual fossilized remains. But trace fossils can still tell us much. If they are animal tracks, how was it walking - on two legs or on four? How fast was it travelling? Was it alone, or in a group? And of course tracks will also tell us with reasonable certainty whether it was herbivorous or carnivorous, and, depending upon the strata in which the tracks were found, how long ago it lived.

Tracks which cannot be associated with a specific animal are given their own name, and that is the case with our little dinosaur here. The dinosaur's name remains unknown. The tracks have been named by science as Atreipus, after their 19th century discoverer, Atreus Wanner. These little footprints (my drawing below, about life-size) have been known from eastern America's Connecticut Valley for some time, and we can deduce that they were made by a small herbivore walking on all fours: the prints of both fore- and hind feet are clearly visible. In fact, the tracks are so small that this dinosaur's body size could not have been much larger than that of a domestic cat's. It's style of locomotion is described as being 'habitually quadrupedal', which is just a way of saying that walking on all fours was the usual thing for it to do.

Reconstructing an animal from its tracks alone is a major challenge in itself, but these delicate, almost dainty tracks drew me to them, and I wanted to know how this little dinosaur might have appeared in life. The skin patterns and colours of my painted reconstruction above are conjectural, but the feet and limbs - long hind legs and shorter front legs - and the walking stance, are highly probable, and are what the Atreipus tracks themselves indicate. At some time in the very early Jurassic, around 205 million years ago, this unknown little dinosaur wandered over what is now the Connecticut Valley, living out its life, and in its wake leaving these modest tracks as our only record of its passing.

Paul E. Olsen and Donald Baird: The ichnogenus Atreipus and its significance for Triassic biostratigraphy: in K. Padian (ed.), The Beginning of the Age of Dinosaurs, Faunal Change Across the Triassic-Jurassic Boundary, Cambridge University Press, New York, 1986, p. 61-87.

Wednesday, July 18, 2012

Disproving Evolution

A couple of evenings ago I overheard the remark in a video phone-in interview that a Fundamentalist Christian creationist with something of a reputation on YouTube was considering becoming a scientist, apparently so that he could disprove evolutionary theory, as it were, from the inside. I won't embarrass him by naming him here, but such an aspiration demonstrates only a lack of any grasp of the way in which scientific method actually functions. To explain:

In science, there is no plan; you simply go wherever the evidence takes you. True enough, parameters can be set up, and based upon sound reasoning and experience, an extrapolated subatomic particle is discovered, or an expected fossil actually turns up in a specific locality. But science does not deal in negatives. So setting out actually to scientifically 'disprove' something is a non sequitur.

Still, let's for the sake of this point assume that it's possible (and allowable within the scientific community). You 'disprove' a theory - and a well-established and long-accepted one at that. What are you left with? A mere vacuum. You have done nothing actually to replace the quashed theory with anything new, with a viable alternative of your own that steps in to replace what you have trounced. To do that, you'd have to marshall your evidence and send a hypothesis of your own down the long and well-worn road that any scientific hypothesis has to tread in order to gain acceptance. In short: you'd actually have to practice science. Real science. And in science, things are neither *'proven' nor 'disproven', just accepted.

It's possible, of course, that some line of scientific reasoning might disprove something else, but it does so simply as a by-product of 'doing what it does', not as an intent. Like the way in which the mechanisms of evolution incidentally disprove creationism... :)

*While proof in the understood sense of the term is not part of the definition of what constitutes a scientific theory, it is true enough that some theories have shown themselves to be so robust that they are to all intents and purposes accepted as fact - evolutionary theory being one of them. And a 'theory' in science has a different meaning to the word in everyday use, which is why the creationist claim that 'evolution is just a theory' is yet another non sequitur.

And this clears up another widely-held misunderstanding by creationists: disproving something in science does not automatically 'prove' something else. So 'disproving' evolutionary theory would not by default establish that supernatural creation had occurred instead. The situation on the ground is that a supernatural means of creation would then have to be accepted and established as a scientific theory in it own right. Good luck with that one, creationists...