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Friday, 17 February 2017

Scientists: please pay more attention to palaeoart

A few years ago I wrote about how the 21st century is a terrific interval for palaeoart because of the wealth of information, discussion of palaeoart theory and diversity of talent we presently enjoy. Never before has so much data on this topic been available to practitioners of the trade, to scientists and historians, or to curious members of the public. The increase in palaeoart talent, a movement of artists exploring the outer regions of palaeoart science and artistry, and hints of wider interest in art of fossil animals are all traceable to these recent developments.

Any palaeoartist you speak to will tell you that there are honed practises and processes that should be applied when executing a palaeoart study. Several decades worth of influential artwork and writing by the likes of Knight, Hallett, Paul, Antón, Conway et al. and others send a unified message: reconstructions of fossil animals should be produced through close study of animal anatomy, both fossil and modern. They demonstrate that palaeoartworks must pass some basic, almost objective tests to be considered scientifically credible, successful examples of the medium.
  • The proportions of the subject should be accurate to those indicated by its fossil remains
  • The skeleton of the subject should fit within the restored soft-tissue volume
  • Depicted poses should conform to predictions of joint motion
  • The soft-tissue volume should - at minimum - be informed by predictions of muscle bulk derived from fossil remains as well as relevant data from modern, related species
  • Soft-tissues restoration should be informed where possible by fossil data, or else via robust predictive techniques, such as phylogenetic bracketing
These points are not controversial. I'm sure any number of modern palaeoartists would list these as their baseline, entry level requirements for bona fide, scientifically-credible palaeoartwork. Further considerations of posing, composition and behaviour become more subjective and debatable - ideas of what we think 'looks right' or is 'most likely' in these areas are influenced by personal preferences, artistic styles and intent of the artwork. Successful palaeoartists can have contrasting ideas about these latter points, and that's fine: so long as our work remains within the realms of scientific plausibility, we are free to experiment and develop unique styles. But at the core of any palaeoartwork must be a reconstruction of a species that conforms to those fundamental aspects listed above.

Although it feels like we live in an enlightened age for palaeoart, some artworks associated with the very people who should be sticklers for scientific precision and reconstruction plausibility fall well short of the most elementary aspects of fossil animal reconstruction. These are not reconstructions for TV shows or films, where creative forces override scientific input. They are not illustrations for books where an overworked generalist illustrator is given a few hours to render an animal they'd not heard of until that morning. These are artworks produced for papers and press releases where scientists - researching palaeontologists with direct access to fossil material and technical literature - have every opportunity to guide and shape the artistic process. And these works are sometimes so scientifically awful that they're almost insulting to those of us who strive to produce credible prehistoric imagery, being critically flawed at the most basic level.

The level of failure in some artworks (not linked to here out of politeness) is sufficient to question whether those involved knew anything about reconstructing anatomy or if they really cared about the artwork at all. And yes, I think we do have to look at the scientists and researchers as being ultimately responsible here. These are artworks produced directly under their control to be associated with their work, and without pressure from publishers or media producers to be fantastic, weird or sensational. Scientists made the decision to produce these palaeoartworks, chose the artist to execute it, chose the level of input to have during its production, and signed off the final product.

In these artworks, even errors which scientists can objectively veto (such as proportions and bone articulations, elements of form such as skull or tooth shape, well-studied soft-tissue anatomies like feathers arrangements on dinosaur wings) are ignored. The result is that these pieces perpetuate errors that were realised as problematic years ago: under-muscled, 'shrink-wrapped' animals; 'bunny handed' theropods; feathered maniraptorans with three free fingers extending from their wings; ichthyosaurs with visible giant eyes; pterosaurs with enormous torsos and so on. The worst offenders show no grasp of basic aspects of animal anatomy, fossil or modern, with outlandish ideas of muscle distribution or proportions which are falsified by the most cursory glance at reference material. It is no exaggeration to say that some recent scientist-led palaeoartworks would not look out of place if produced in the 1830s. 

And we - educators, scientists, palaeoartists - should feel ticked off about this. Scientist-led palaeoart should be the best there is: carefully-executed, evidence-led syntheses of research conclusions in compelling artworks. It should convey to people how the subject appeared and behaved based on both new, cutting-edge research and the best of the science which preceded it. There is no reason not to take the same attitude to our palaeoart that we do to the rest of our studies. It is frowned upon to take half-measure approaches to descriptions, statistical analyses or cladistic methodology, so why is palaeoart exempt? Making crass, basic errors in animal reconstruction is no different to executing a flawed study or analysis. Both ignore data, advice and theory documented in palaeontological literature, and both show little regard for the techniques developed by pioneers of the process. Moreover, when they make it to publication, both imply that half-baked approaches are worthy of equal consideration to more carefully executed examples. Scientists will know the feeling of frustration when work directly relevant to a paper is not cited: lousy palaeoart is guilty of ignoring the theory and development of an entire field

A baffling aspect to this problem is that scientists routinely seek expertise lacking on research teams. Need a fossil prepared but lack the skulls? Seek assistance from a preparator. Need to crunch some stats but not sure how? Contact a colleague with statistical expertise. What we don't do with our science is assume our intuition and instincts about a topic are enough to guide us alone: we defer to those with the training, specific knowledge and experience to do the jobs we can't. And we would never employ an equally inexperienced individual and guide them through a process we lack all experience of ourselves.

But this is exactly what we do with palaeoartistry. Executing a palaeoart study requires a grasp of anatomy (and not just bones!), an ability to reconstruct/interpret fossil remains, a healthy grasp of living animal form, and an ability to translate all this into an artistic creation. These are not skills that everyone has, or that even all palaeontologists have. There are numerous specialisms in palaeontology, and not all of them are associated with the expertise ideal for consulting on palaeoartworks. Fossil bones do not exude a radiation which means those who work with them automatically know everything about palaeoart methods and theory. And yet it seems some scientists think it does, resulting in ill-founded advice for naive artists and approval of poor, flawed work. I am not the first person to raise this point (it has been mentioned in palaeoart literature since the 1980s), but it seems to fall on deaf ears.

Some readers may be wondering if this matters - so what if we have the odd wobbly looking reconstruction every now and then? Consider these points. Firstly, if scientists are so relaxed about palaeoart that they have no regard for even getting fundamental aspects correct, then what, really, is the point of the art in the first place? What can art of that quality really add to our field? It can't be held up as an accurate representation of the animal itself, and knowledgeable educators will avoid it or abandon it the moment a superior alternative becomes available (which, given the popularity of palaeoart online, is normally a couple of days after a new discovery. Indeed, awful PR palaeoart normally spurs more alternative versions, and with faster turnaround times). Badly produced palaeoart is basically destined to be ignored by those in the know, reflects poorly on those involved in its production, and ends up being an embarrassing aspect of the publication.

Secondly, scientist-led palaeoart is often the basis for derivative artwork, whether it's good or bad. Whereas people might expect prehistoric animals seen in film and TV to be embellished and enhanced, scientist-endorsed artwork carries the weight of expert approval. For non-specialist illustrators, they're an obvious source of information and errors are carried over into next generation work. Scientists need to realise that the half-lives of palaeoart are often much longer than any press articles or even scientific papers: they have long-lasting impacts on public perception and even inform scientific hypotheses. Darren Naish recently wrote more about these issues at length here.

Thirdly, there are scores of competent palaeoartists awaiting opportunities to work with scientists, and their prior knowledge of reconstruction processes and anatomy would fill knowledge gaps in some teams. Not only do these individuals have the skills needed to understand a fossil specimen and technical paper, and are thus able to produce credible artwork without constant academic input, but their experience means they can converse with scientists at (or close to) a technical level. This allows for detailed conversations about the specifics of the reconstruction and development of new ideas and insights into the life appearance of the subject organism. Experienced palaeoartists are more than just people who make pretty pictures: they're peers and colleagues of scientists, and able to augment research when given the opportunity.

Lastly, it is widely known that the palaeoart industry has a problem maintaining employment for even its most talented individuals, and in this context hiring non-specialists, especially if the research team is not palaeoart savvy, is ludicrous - why not hire the right people for the job? There are many early-career palaeoartists available if tight budgets are a concern, as well as numerous veterans who can offer highly polished art and rapid turnaround times if time is tight. Finding these people is as easy as opening modern palaeoart books, asking colleagues for recommendations or even a Google search. The wealth of easily-accessed palaeoart talent makes it inexcusable not to bring specialist artists on board for palaeoart projects.

And 'inexcusable' sums up my feeling on this topic pretty well. The fact that many scientist-led artworks are really amazing shows that high quality palaeoart of this nature is achievable if scientists care enough about its production. But the availability of palaeoart-relevant information, the growing body of literature on palaeoart theory, the willingness and accessibility of talented artists, and the demands of modern scientific standards make academically-driven, scientifically-rotten palaeoart inexcusable in the modern day. I'm not arguing that scientist-led palaeoart has to be perfect. I'm not arguing that scientist-led palaeoart has to conform to specific conventions of style, or to constrained ideas of life appearance. But I am arguing that scientist-led palaeoart should look like someone gave a damn about the final product.


Wednesday, 18 January 2017

New paper: when the short-necked, giant azhdarchid pterosaur Hatzegopteryx ruled Late Cretaceous Romania

In an ideal world, all blog posts would start with images like this one. (Edited talk title slide I used back at SVPCA 2013 - we've been working on the project discussed below for a while now.)
In the last year we've spoken at great length about the giant azhdarchid pterosaurs, those toothless, tube-necked, 10 m wingspan behemoths that awesomed their way into existence at the end of the Cretaceous Period (if you need more of an introduction, check out these posts). Of the three named giant species, we've discussed what is really known of Quetzalcoatlus northropi and outlined why their least famous representative - Arambourgiania philadelphiae - is worthy of greater attention. But we've yet to tackle the most recently named and, in some respects, intriguing giant of them all: the heavily built, giant-headed Romanian behemoth Hatzegopteryx thambema.

A quick primer for those of you who aren't familiar with Hatzegopteryx. The first fossils of this Romanian, Maastrichtian pterosaur were announced in 1991 but, on account of their considerable size and robustness, they were interpreted as belonging to a large theropod, not a pterosaur. Eric Buffetaut and colleagues reassessed these bones some years later and made their azhdarchid pterosaur identity apparent (Buffetaut et al. 2002, 2003). As with all giant azhdarchids, only scraps of Hatzegopteryx are known. Bits of skull and a broken humerus from the Densuș Ciula Formation form the holotype, and a large femoral shaft from the same formation may belong to this animal as well. All these elements are remarkable for their size - wingspan estimates of 10-12 m seem sensible (Buffetaut et al. 2003; Witton and Habib 2010) - as well as an unusual degree of internal reinforcement. In addition to thick bone walls (4-6 mm, which doesn't seem much, but is impressive for a pterodactyloid pterosaur), both Haztegopteryx humeral and jaw elements possess large amounts of coarse spongiose bone. This reinforcement may be related to the evolution of some very substantial anatomy. Buffetaut et al. (2003) were able to make a compelling case for a 50 cm wide jaw for this animal, and even conservative extrapolation of that figure suggests Hatzegopteryx was among the longest-jawed non-marine tetrapods to have ever lived (Witton 2013). Such an unusual pterosaur seems fitting for its provenance, the Densuș Ciula Formation representing part of the ancient and peculiar 'Hateg Island' ecosystem. This setting will be familiar to many as an ancient, large Cretaceous island well-separated from the rest of Europe by deep seas, and populated by archaic, sometimes dwarfed or otherwise peculiar dinosaur lineages (e.g. Benton et al. 2010).

Since Hatzegopteryx was named in 2002 several Romanian sites of equal age and palaeoenvironmental setting have provided new fossils of giant pterosaurs. Some of them have a real Hatzegopteryx flavour (Vremir 2010; Vremir et al. 2013) and, although a complete specimen remains far from realised, a crude picture of this giant pterosaur is slowly being put together. These specimens are being worked on by different teams and, hopefully soon, we'll have a lot of new Haztegopteryx (or at least large azhdarchid) material to play with.

But that's not to say there's nothing new about Hatzegopteryx to discuss here. In fact, today Darren Naish and I published a new, open-access peer-reviewed form-function assessment of a Hatzegopteryx vertebra which takes us a step closer to understanding this enigmatic animal (Naish and Witton 2017). Long-term readers of this blog or Tetrapod Zoology will know that Darren and I team up semi-regularly to write about azhdarchid palaeobiology and may have played a role in shaping modern interpretations of these pterosaurs (Witton and Naish 2008, 2013). Our work this time focuses on a remarkable pterosaur bone known as EME 315, a giant azhdarchid cervical briefly described by Vremir (2010) and likely representing the first described axial element of Hatzegopteryx*. Our ideas about the proportions, structural properties and surrounding musculature of this bone are quite different to what has previously been said about Hatzegopteryx and other azhdarchids and, if we were sensible people, we would have kept quiet until today. However, our enthusiasm for the project and as well as a long, complex writing process has made for a particularly leaky embargo (artwork of our new interpretation of Hatzegopteryx made it into my art book, Recreating an Age of Reptiles, of instance) and many readers may be aware of our punchline: Hatzegopteryx may have a been a particularly powerful and 'short necked' azhdarchid, and maybe even a dominant predator of the topsy-turvy island ecosystem of ancient Hațeg. With the cat already somewhat out of the bag, let's take a look at our substantiation for what is a bold, counter-intuitive claim: could a pterosaur, even a giant azhdarchid, have been a formidable arch predator?

*EME 315 is from the Sebeș Formation, and thus not from the same formation as the H. thambema type, and does not overlap with our existing thambema inventory. However, it has the same characteristically thick bone walls, spongiose internal texture and stupendous size that we can recognise in the Hatzegopteryx type specimen. This, and its extremely close geographic and chronostratigraphic (Maastrichtian) occurrence, make referral to Hatzegopteryx reasonable, although we hedge our bets a little in not referring it to H. thambema itself. We settled on H. sp.


Mighty EME 315 as presented in our paper. The scale bar represents 100 mm - for a pterosaur vertebra, this is a massive bone. Note the graph at the base of the image - for its size, EME 315 is a clear outlier to other azhdarchid cervical specimens. That's the Arambourgiania type cervical V for contrast. From Naish and Witton (2017).

Estimating the neck length of Hatzegopteryx

Figuring out the proportions of an animal from one bone is not easy, and is especially challenging for a group with a subpar fossil record like azhdarchids. We were thus quite careful not to push our proportional interpretations of EME 315 too far, but some aspects of the size and basic anatomy of the EME 315 individual can be deduced quite readily. In turn, they provide some insight into the basic shape of Hatzegopteryx. It goes without saying that EME 315 was from an enormous animal. Its width is almost three times that of the next largest known pterosaur vertebra, and that puts it into the 'giant azhdarchid' category without hesitation. We were able to use some fundamental aspects of pterosaur neck construction to conclude that EME 315 might belong to similarly-sized animal as the (estimated) 10-12 m wingspan Hatzegopteryx holotype individual, the same one that has the 50 cm wide skull. That makes sense to me - an animal with a jaw that wide - and who knows how long? - is going to need a chunky set of neck bones to support and operate it.

Complete azhdarchid necks are rare, but we were able to track down data for six associated or reconstructed cervical series to plot their scaling regimes and predict the neck length for EME 315. These vertebral series also allowed us to make a predication for where in the neck EME 315 came from - we concluded that it likely represents a seventh cervical, one of the smaller vertebrae from the back of the 'functional' cervical skeleton. Our identification contradicts Vremir (2010), who suggested it was a third cervical, but there are good reasons to doubt this ID. Rehashing our long discussion of the vertebral ID here would be both tedious and unnecessary, especially given that interested readers can head to the paper for our full assessment. It will suffice to say that we're confident a cervical VII identification is much more likely than a cervical III, and this was the assumption we employed for the neck length estimate.

Our neck dataset predicted a cervical III-VII length of 1.5 m for EME 315, which sounds impressive, until you realise that the much smaller, 4.6 m wingspan azhdarchid i>Quetzalcoatlus
sp. has a neck of equal size - 1.49 m long (below). By contrast, the giant holotype cervical of Arambourgiania, which probably also represents a gigantic animal of 10 m(ish) wingspan, gives a reconstructed cervical III-VII length of 2.65 m. So EME 315 has a neck no longer than that of a pterosaur with perhaps half its wingspan, and much shorter than that of at least one other giant species. We thus suggest that, for its size, Hatzegopteryx had an abbreviated neck skeleton. Of course, this is not the first time the potential of short-necks in azhdarchids has been raised - it's not even the first time Darren and I have discussed it in a peer-reviewed paper (Vremir et al. 2015). But Naish and Witton (2017) is the first time this hypothesis has been outlined in detail and substantiated with a dataset of neck bone measurements, so it feels that we've elevated the idea to something that can be discussed and challenged more legitimately.

Neck lengths in large and giant azhdarchids. A and B show Hatzegopteryx in lateral and dorsal aspect (B shows EME 315 and the holotype jaw bones only, but gives you an idea how chunky its neck was); C, shows Arambourgiania (known bones in white) with a reconstructed neck (grey elements); D and E, Quetzalcoatlus sp., lateral skeletal and dorsal view of skull and neck. From Naish and Witton (2017).
A short-necked azhdarchid may not seem like a big deal, but they're potentially important for at least two reasons. The first is that azhdarchids are in part classified by their super-elongate neck bones, but our data indicates that this may not be a universal trait. We used our neck bone dataset to predict that the longest bone in the EME 315 neck - cervical V - would have only just exceed 400 mm, which makes its length less than twice the width of EME 315. By contrast, a typical azhdarchid cervical V is 5-8 times longer than wide. We need to find a complete Hatzegopteryx neck without hypertrophied mid-series cervicals to confirm our calculations, and have little idea how common this 'short necked' variant might be within Azhdarchidae as a whole (we helped describe another proportionally short Romanian azhdarchid vertebra, R.2395, which could be a second 'short necked' species a few years back - Vremir et al. 2015), but - if verified - a 'short necked' morph could complicate how we characterise Azhdarchidae.

Secondly, and perhaps of more general interest, this calculation adds to increasing evidence that azhdarchids may have differed rather dramatically in overall proportions. A number of workers have criticised the concept of azhdarchid anatomical uniformity in recent years (Vremir et al. 2012, 2013, 2015; Witton 2013), and our new paper adds further force to that argument: data for skulls, wing morphologies and now necks hint at a range of bauplans within the group. Their categorisation may not be as simple as 'robust' and 'gracile' forms as I've previously suggested (Witton 2013), but it's increasingly difficult to view Azhdarchidae as a parade of Quetzalcoatlus clones. This is of interest to not only researchers - differing forms might indicate differing behaviours and ecologies - but is something for artists to take note of too.

Arambourgiania vs. Hatzegopteryx: Neck Wars

Just how does our new 'short-necked' Hatzegopteryx compare to a regular, long-necked giant form? Something like this. That's our Industry Standard 5.8 m tall male Masai giraffe on the left, the Disacknowledgement centre left, Arambourigania centre right, and Captain SuperChunk on the right. As restored here, Hatzegopteryx is nowhere near as tall as Arambourgiania, but the bulk of its skull and neck likely made it a more formidable animal.
Being interested in azhdarchid ecology, we wondered how the different proportions and internal anatomy of giant azhdarchid cervicals might influence their ability to withstand neck stresses caused by foraging, supporting their heads and so on. We performed a range of bending strength assessments on both the robust and thick-walled EME 315 and the elongate, slender-walled tube that is the giant holotype Arambourgiania cervical V. There are too many variants of the experiments to report all the results here (again, see the paper for details), but the TL;DR version is that the performance difference was consistently huge. OK, no-one was expecting the long, gracile Arambourgiania vertebra to outperform EME 315 in a bone strength competition, but the difference between the two is significant enough to indicate very different neck functions. Even comparing Arambourgiania's best bending performance against EME 315's worst, the latter is ten times stronger. We extrapolated our data to assess bending strength in the longest (and therefore weakest) neck bone in the Hatzegopteryx skeleton (a hypothetical cervical V) and it still outperformed its counterpart in Arambourgiania by several biomechanical miles. A larger cross-section, shorter vertebral body and thicker bone walls all contribute to EME 315's stellar bending performance, and we identify several additional aspects of reinforcement and strengthening of EME 315 in our paper.

It's therefore clear that the neck structure of Hatzegopteryx was in a different biomechanical league to that of Arambourgiania, and this implies vastly different neck functions in these species. We expect that one factor in this distinction is the wide, presumably heavy head ascribed to Hatzegopteryx, and infer that the weaker neck bones of Arambourgiania would require a narrower, gracile variant of the azhdarchid skull (maybe something a bit Q. sp-like). But the strength of the Hatzegopteryx neck seems high even accounting for its likely skull size, and we postulate that additional loads - big prey items, violent uses of the head and beak during foraging - may have contributed to its boosted structural properties.

Supporting this hypothesis are features indicative of large soft-tissue volumes around the neck of Haztegopteryx. Classically, the reduced features of azhdarchid neck vertebrae have seen them regarded - and depicted - with minimised cervical musculature and ligaments. We regard this view as problematic for a number of reasons. The first is that complete azhdarchid necks show that only the mid-series vertebrae lack complex anatomy indicative of muscle and ligament attachment. The complexity of their neck skeleton as a whole is not far off that of a 'normal' tetrapod, where the anterior and posterior vertebrae are relatively complicated to allow for greater volumes and intricacies of soft-tissues in these regions. Yes, azhdarchids do reduce their vertebral complexity further than most species, but not so far that we should assume their in vivo necks were little more than bony tubes covered in skin.
Reconstructed cervical series and associated azhdarchid specimens show that their necks were not just made of bony tubes, but variably complicated bones in a pattern structurally typical of other long-necked tetrapods. What might this mean for soft-tissue development? One obvious implication is that at least the anterior and posterior neck regions were likely fleshier than often considered. From Naish and Witton (2017).

Furthermore, assuming azhdarchid neck muscles and ligaments were basically homologous to those of living reptiles, some attachment sites must be regarded as expanded, not shrunken. These include particularly deep shoulder blades (for anchoring neck elevators and lateral flexors) and deep basins at the back of the cranium (for anchoring neck-skull extensors). While famously lacking vertebral processes on their mid-series cervicals, a suite of scars along the dorsal surfaces of azhdarchid cervicals betray long muscle or ligament attachments, while the vertebrae at the extremes of the neck have well-developed neural spines. Most startlingly, the expansion of their zygagpophyses take on new significance when we realise that these structures anchor numerous neck muscles in living sauropsids. So yes, azhdarchids certainly lost and reduced some areas of neck muscle attachment, but others were enhanced. The peculiar cervical anatomy of azhdarchids likely reflects an economising, rather than all-round loss, of neck soft-tissues.

Bringing this discussion of soft-tissue back to the giants, we have to look at Arambourgiania and Hatzegopteryx as once again reflecting very different types of animals. Our Arambourgiania cervical has much smaller areas for soft-tissue attachment compared to EME 315, which has immense, complicated anatomy in all the areas we associate with cervical soft-tissues in living sauropsids. This may partly be explained by EME 315 and the holotype Arambourgiania cervical being from different parts of the neck, but complete azhdarchid necks suggest these bones provide some general sense of neighbouring cervical skeleton anatomy - it would be weird if the Arambourgiania cervical V was juxtaposed with a massive, EME 315-type bone, for instance. We take this to indicate that EME 315 was not only a strong bone in a robust neck, but that the cervical skeleton of this animal was perhaps wrapped in large, powerful muscles and ligaments - exactly the sort of soft-tissues that can deliver those demands hinted at by our bending strength tests, and would be needed to wield that enormous head.

Ecological diversity of giant azhdarchids

These results get most interesting when we plug them into the bigger picture of giant azhdarchid anatomy and lifestyles, because there seem to be a couple of different stories being hinted at here. For example, we can take the long neck, relatively low cervical bending strength and lessened areas of muscle attachment in Arambourgiania as placing restrictions on prey size as well as precluding violent, dynamic foraging strategies and other behaviours that would impart high stresses on its neck anatomy. Assuming the 'terrestrial stalker' model for azhdarchid lifestyles (Witton and Naish 2008, 2015) applies to the giants, we might imagine Arambourgiania as preferring smaller prey and relatively lightweight foodstuffs: smallish animals, the eggs of larger reptiles and birds, and generally anything that wouldn't put up too much of a fight. These would still be formidable animals - remember that they stand 4-5 m tall - but all indications are that they represent the 'lightweight' end of the azhdarchid palaeoecology spectrum, and likely behaved accordingly.

Giant azhdarchid pterosaurs, diet edition. What we know of Arambourgiania implies they preferred smaller prey, such as diminutive dinosaurs, which may have been caught using relatively undemanding means.From Naish and Witton (2017).
The emerging picture is rather different for Hatzegopteryx. Here, we can plug our results of a relatively short, strong neck and high fractions of cervical musculature into its overall robust construction, reinforced bones, massive and wide jaws, and stupendous size. Collectively, this paints an image of a far more solidly built and powerful animal than Arambourgiania. If - as most of us now seem to think - azhdarchids were 'terrestrial stalkers', we can imagine Hatzegopteryx as as a giant azhdarchid turned up to 11: a prairie-roaming giant with elevated maximum prey size and capacity for violent and forceful foraging tactics. Given how dangerous we know modern azhdarchid-like birds can be, and armed with a powerful neck and giant, reinforced skull, we might even imagine Hatzegopteryx using powerful bites, bludgeoning blows of its head and stabbing motions to tackle prey too large to swallow whole. If we're right, Hatzegopteryx was both a truly awesome, but also entirely terrifying animal. There is not exact modern analogue for this sort of creature, but if you imagine a giant mix of a shoebill stork, a ground hornbill, and the Terminator you might be pretty close.

The Hatzapocalypse: a group of foraging Hatzegopteryx find a chunky, subadult rhabdodontid Zalmoxes. Rather than pursuing baby sauropods or raiding nests, our interpretation of Hatzegopteryx implies it was a dangerous predator of mid-sized or larger animals. Whether it used the catchphrase "Hatze la vista, baby" after each successful hunt remains a matter of debate among scientists. From Naish and Witton (2017).
It is significant to this hypothesis that no large theropods are known from the same sediments as Hatzegopteryx. We can never say never with negative evidence, but the Maastrichtian sediments of Romania have been sampled for centuries and not a single large predatory dinosaur bone has been found - not even a single tooth. These are the only sediments in the world where you stand a better chance of finding a giant pterosaur than a large theropod, and it's hard not to look at that as intriguing. Hatzegopteryx is the only carnivorous animal we know of from this time and place which was large enough, and robust enough, to tackle good-sized prey, and we postulate that it may have taken the 'arch predator' niche occupied by theropods elsewhere in the world.

Further work on new Romanian pterosaur fossils, as well as new discoveries, will show if this view is correct or not. Moreover, they'll help answer the many, many questions that remain concerning giant azhdarchid anatomy, evolution and palaeobiology. For me, among the most significant of these questions is what Hatzegopteryx signifies in the context of Late Cretaceous pterosaur disparity, ecological diversity and their eventual extinction. The latter is something we discuss briefly in our paper, as we've classically interpreted Maastrichtian pterosaurs as a biologically conservative group living on borrowed time. But our new work on Hatzegopteryx, as well as the potential recovery of a small-bodied pterosaur from Campanian sediments of Canada (Martin-Silverstone et al. 2016), and ongoing work on non-azhdarchid pterosaurs found near to the K/Pg boundary from Morocco (these being presented at SVPCA 2016 by Nick Longrich and colleagues) complicates that picture. It's looking more and more likely that our perception of the last pterosaurs as a low diversity, dying group has been distorted by sampling biases, and they may have actually been doing just fine until the end of the Mesozoic. Perhaps pterosaur extinction was a more significant event than previously realised.

But these questions will have to wait. For now, it's satisfying to finally be talking about these new data on what was clearly one of the coolest animals in the pterosaur canon. I'll leave you with a thought echoed from our paper: whether the ideas discussed here are right or wrong, the fact we can discuss 'the Hatzegopteryx arch predator hypothesis' without laughing is a real sign that interpretations of azhdarchids - and pterosaurs generally - have moved on considerably. Could our colleagues of 50-60 years ago have imagined pterosaurs - considered lame, underweight, creaky-winged gliding things - would be discussed in this sort of context? I imagine not.

(We're not done with pterosaurs, or new papers, at the blog just yet: stay tuned for more pterosaur news in the very near future.)

This paper, blog post and paintings are made possible by Patreon

The content featured here is sponsored by another group of short-necked tetrapods, my Patreon backers. Supporting my blog from $1 a month helps me produce researched and detailed articles with paintings to accompany them, as well as peer-reviewed papers on which to base them. In return for being a Patreon backer you get access to bonus blog content: additional commentary, in-progress sneak-previews of paintings, high-resolution artwork, and even free prints. For this post, we'll be looking the four years of development that went into the Hatzegopteryx painting shown above, revealing the earliest versions up to the final, published version. Sign up to Patreon to get access to this and the rest of my exclusive content!


References

  • Buffetaut, E., Grigorescu, D., & Csiki, Z. (2002). A new giant pterosaur with a robust skull from the latest Cretaceous of Romania. Naturwissenschaften, 89(4), 180-184.
  • Buffetaut, E., Grigorescu, D., & Csiki, Z. (2003). Giant azhdarchid pterosaurs from the terminal Cretaceous of Transylvania (western Romania). Geological Society, London, Special Publications, 217(1), 91-104.
  • Martin-Silverstone, E., Witton, M. P., Arbour, V. M., & Currie, P. J. (2016). A small azhdarchoid pterosaur from the latest Cretaceous, the age of flying giants. Royal Society Open Science, 3(8), 160333.
  • Naish, D. & Witton, M. P. (2017). Neck biomechanics indicate that giant Transylvanian azhdarchid pterosaurs were short-necked arch predators. PeerJ, 5:e2908; DOI 10.7717/peerj.2908
  • Vremir, M. (2010). New faunal elements from the Late Cretaceous (Maastrichtian) continental deposits of Sebeş area (Transylvania). Acta Musei Sabesiensis, 2, 635-684.
  • Vremir, M., Kellner, A. W., Naish, D., & Dyke, G. J. (2013). A new azhdarchid pterosaur from the Late Cretaceous of the Transylvanian Basin, Romania: implications for azhdarchid diversity and distribution. PLoS One, 8(1), e54268.
  • Vremir, M., Witton, M., Naish, D., Dyke, G., Brusatte, S. L., Norell, M., & Totoianu, R. (2015). A Medium-Sized Robust-Necked Azhdarchid Pterosaur (Pterodactyloidea: Azhdarchidae) from the Maastrichtian of Pui (Haţ eg Basin, Transylvania, Romania). American Museum Novitates, (3827), 1-16.
  • Witton, M. P. (2013). Pterosaurs: natural history, evolution, anatomy. Princeton University Press.
  • Witton, M. P., & Naish, D. (2008). A reappraisal of azhdarchid pterosaur functional morphology and paleoecology. PLoS one, 3(5), e2271.
  • Witton, M. P., & Naish, D. (2015). Azhdarchid pterosaurs: water-trawling pelican mimics or “terrestrial stalkers”?. Acta Palaeontologica Polonica, 60(3), 651-660.

Tuesday, 20 December 2016

The popularity of dinosaurs - for better, for worse

This article is being cross-posted at the website of the London-based 2016 Popularizing Palaeontology workshop as part of a series of blog posts focusing on the discussions and themes of that event. Over the course of this two day workshop curators, artists, historians and palaeontologists presented talks and led round-table discussions about the history and current state of palaeontological outreach. I presented a talk at this workshop - entitled 'The importance and impact of palaeoart in palaeontological outreach', which you can see here. The following is not based on this talk, but rather a theme that seemed - to me - to be consistent across many presentations and discussions, including my own.

Whether it's a giant armoured thyreophoran like Panoplosaurus mirus (thanks to the Empress of Ankylosauria, Victoria Arbour, for advice on this restoration) or a svelte theropod like Chirostenotes pergracilis, everyone likes dinosaurs and we - palaeontologists - like using them in our outreach. But are dinosaurs really universally popular and appropriate for the wide range of outreach we use them in?
The Popularizing Palaeontology workshops held in August 2016 presented fascinating insights into the history and current state of palaeontological outreach. Our many talks and roundtable discussions touched varied topics but several central themes emerged, of which one was the prevalence of dinosaurs in virtually all palaeontological PR exercises. Whatever we discussed - the history of museums, the palaeoart industry, public interest in research or palaeontological influences on cinema - dinosaurs were almost always involved. Even if they weren’t a main focus, their influence there - catalysing certain events, influencing decisions, eclipsing other outreach topics. It would be wrong to say popularising palaeontology is totally synonymous with popularising dinosaurs, but for better and worse, these animals have a major role and influence over public outreach of palaeontological science.

The success of dinosaurs in outreach

Exactly why dinosaurs occupy such an important and influential space in popular culture remains largely mysterious. On paper, dinosaurs are a group of extinct reptiles which are not - superficially at least - so different from other long-dead sauropsids, and yet they have somehow gained global fame and many dedicated followers. My suspicion is that dinosaurs uniquely combine obviously amazing, ‘high impact’ anatomy - large size, fantastic skeletal structures such as horns, huge teeth and so on - with bauplans that are easily understood by the general public, without being so familiar that they’re pedestrian. For instance, everyone can appreciate Allosaurus as an active, large bodied predator even if just looking at its skeleton in a museum, but - as bird-like as it is in detail - the overall form is somewhat alien and intriguing. Other fossil groups, such as ancient carnivorans or whales, are impressive enough but perhaps also too familiar to inspire our imaginations in the same way. At the other end of the spectrum are extinct creatures which are just too unusual for widespread appreciation. Perhaps their anatomy is too strange or their life histories are too obscure and difficult to relate to familiar biology. This applies to many extinct invertebrates, as well as several types of weirder vertebrates. Dinosaur biology is thus near perfect for outreach material: they’re visually impressive, anatomically and biologically accessible, but different enough to warrant interest. Whether this is the actual basis for dinosaurian appeal or not, museum staff, educators and merchandisers have realised for over 150 years that dinosaurs are an excellent way to interest the public and make money, and given them prominent roles in outreach. Aiding any intuitive draw we have to dinosaurs is a lot of social inertia, and part of the enduring appeal of dinosaurs is a long history of ingraining them into popular culture.

The success of dinosaurs in the public eye almost certainly reflects many varied influences, but their unique anatomical qualities may play an important role. Does any other fossil group combine interesting, ‘high impact’ biology, in a format that the public can easily grasp, in the way that dinosaurs do?

For those of us interested in science education, dinosaurs are one of the most important and potent tools at our disposal. We see them as not only fascinating subjects in their own right but as a way to introduce ‘bigger picture’, perhaps fundamentally more important, scientific concepts to lay audiences. Dinosaurs are gateways to discussions of evolution, adaptation, anatomy, biological diversity, extinction, geological time and the changing nature of the planet. They provide, as charismatic and fantastic creatures, perfect characters to maintain interest in discussions of these sometimes complex concepts, and well-known Mesozoic dramas - the breakup of Pangea, formation of the Deccan Trapps, the Chicxulub Impact - offer rich backgrounds to stage our conversations. Dinosaurs are more than just awesome animals: they’re public ambassadors for science, facts and intelligent thinking.

We cannot ignore the economic value of dinosaurs, too - and not just to Hollywood movie makers and toy manufacturers. Dinosaurs provide academia and its satellite industries with vital income because of their easy marketability and merchandising potential. Public interest in dinosaur news, books and artwork keeps authors and palaeoartists in work, while the pull of dinosaur exhibitions in natural history museums not only keeps turnstiles spinning but brings essential revenue - in the form of gift shop purchases, entry fees and cafe visits - to these underfunded venues. I don’t know that anyone has ever attempted to work out the net worth of dinosaurs to education, but, globally, their appeal must bring millions of pounds into venues that perform outreach every year.

Too much of a good thing?

So hurrah for dinosaurs, then, and their role as not only fascinating subjects for research and art, but as bankable, relatable and demanded elements of modern culture. But the popularity of dinosaurs does have an impact on other aspects of palaeontological PR, and in some conversations at our workshop ‘dinosaur’ almost became a bit of dirty word. No-one will deny the positive aspects of dinosaur popularity, but their dominance in popularised palaeontology influences outreach strategies, merchandising and public expectation, and not always in a positive way.

Some of the problems caused by dinosaurs were outlined in detail during talks at our workshop. We heard that a large portion of natural history museum visitors are exclusively concerned with seeing dinosaur exhibits, challenging natural history museums to use the rest of their collections in a meaningful, impactful manner. This is despite many museum goers being unable to distinguish dinosaur remains from those of other animals without the aid of helpful signage. It seems that, for some museum visitors, dinosaurs act like a brand label, or justification for interest, rather than an excuse to visit a museum for a rounded educational experience.

We also heard that bringing attention to non-dinosaur groups can be extremely difficult, and the less dinosaur-like they are, the harder it is. Groups like pre-Cenozoic synapsids, extinct invertebrates, fossil fish and so on struggle for attention and require highly creative outreach tactics to receive any interest. One of the commonest strategies - used frequently for semi-technical books on fossil animals (below) - is to make sure dinosaurs remain prominently mentioned even in those events or products which are focused on completely unrelated groups of animals. We just don’t trust most non-dinosaur clades to draw crowds or revenue on their own and have to spin them as being relevant to dinosaurs in some way. Tellingly, the only groups to escape frequent dinosaur namechecking are those which are already somewhat ‘dinosaur-like’. Giant fossil mammals, pterosaurs and Mesozoic marine reptiles share aspects of size and gross appearance with Mesozoic dinosaurs and might be seen as ‘honorary dinosaurs’ by the public, and perhaps mistakenly interpreted as the genuine article by many. Both dinosaur-targeted museum visits and our resistance to promote palaeontological topics without a dinosaurian safety net questions whether dinosaurs are a genuine ‘gateway’ to wider scientific education, and perhaps suggests a rather narrower interest in prehistoric life among the public.

Just some of the non-dinosaurian textbooks coming your way in 2017. Probably.
Our group also raised the association between dinosaur outreach and very young demographics, and the challenge this presented to educators. The problem isn’t that many children are naturally interested in dinosaurs - if anything, this is something to celebrate and encourage - but the impact this association has on older audiences. Many adults assume that anything to do with dinosaurs, and by extension any prehistoric animal, is automatically related to children, and often very young children. This becomes an issue for to those attempting to perform outreach or market palaeontologically-informed products to older audiences, and particularly outside of online venues. Experience shows that ‘real world’ dinosaur events - regardless of venue, event type or advertising theme - will be primarily stocked by children and parents expecting child-friendly media. I’ve experienced this many times in my outreach career, such as bowing to pressure for colouring-in stations at a palaeoart gallery, being asked whether a public lecture (entitled Palaeoart: the Never Ending Quest for Accuracy) was suitable for toddlers, and being invited to run art stalls and events for older audiences at dinosaur-themed events to find few interested people over 10 years of age.

The general expectation that dinosaur-related events or products skew towards children presents a complex set of challenges. Firstly, it can lead to older audiences deciding a priori that they cannot take anything away from dinosaur outreach because the event - whatever it is - is ‘just for kids’. I’m sure many of us have seen how ‘switched off’ parents of young dinosaur fanatics are when visiting outreach events, even though the people their children are speaking to may be expert scientists, experienced fossil hunters or world-renowned palaeoartists. Secondly, mismatched expectations of outreach events can be frustrating for both outreachers and audiences: attendees may wonder why a dinosaur event is pitched above the level of their children, while outreachers may feel over-prepared or over-invested in their activity programme when confronted with only young audiences. Perhaps the most concerning issue is that many outreachers and merchandisers use young demographics as an excuse for low scientific standards and sensationalism, promoting outdated, erroneous and sometimes idiosyncratic views of palaeontology because their audience is too young and insufficiently educated to know otherwise, or ignoring scientific data where it might curb child appeal. I am sure most readers can think of numerous examples of products - many labelled as ‘educational’ - which show evidence of this, and it’s easy to see how this attitude may play a major role in perpetuating outdated and erroneous ideas about the past.

One of our final discussion touched on perhaps another issue faced by dinosaur outreach: the schism between public and palaeontological appreciation of what dinosaurs are. For palaeontologists, dinosaurs are a constantly - and sometimes rapidly - evolving set of hypotheses and ideas, and this is what we generally try to present to the world in our outreach. But certain dinosaur concepts outgrew palaeontologist-steered media long ago and now occupy their own place in popular culture, one almost entirely divorced from developments of dinosaur science and instead orbiting their portrayals in film, TV and popular literature. Most of these products - even those produced in the last few years - stick to now long-outdated 20th century interpretations of dinosaur biology and, divorced from guiding hands of scientists, solely emphasise marketable aspects such as their size, perceived ferociousness, and unusual anatomy. The result is a public largely familiar with dinosaurs in a scientifically-distanced, simplified and monstrous form rather than the animals reconstructed through biological and geological sciences, and with little appreciation for their evolutionary context, the scientific techniques used to understand them, or their relationship to wider, ‘core themes’ of scientific outreach. Recent studies partly vindicate this view in showing that the public are generally unaware of even the most basic aspects of dinosaur science, such as the near 50-year old revision from the classic ‘tail-dragging’ posture to an elevated tail and horizontal body attitude (Ross et al. 2013). This is despite museums, artwork, documentaries and some of the most successful blockbuster movies of all time showing the latter since at least the 1990s. This being the case (and with an added caveat that the study in question was relatively small), perhaps our issue with dinosaur education is more severe than we thought: are people really engaging with dinosaur media at all, or are our subjects of research, artwork, and hallowed gateways to other sciences little more than time-fillers and distractions?

Despite the best efforts of many scientists, the public at large seem to associate dinosaurs with considerably outdated interpretations and monstrous creatures. Reviewing recent successful entries into one of the most widely-accessed sources of popular dinosaur culture - Hollywood movies - is this surprising? Perhaps the most visually progressive rendering in this set are the sparsely feathered dromaeosaurs from Pixar’s The Good Dinosaur (bottom right). However, the state of their integument still recalls dinosaur palaeoart from the mid-1990s, and not the extensive feather body covering shown by fossil evidence and now commonly restored over certain dinosaur species. Image sources, from top row down; King Kong (2005); Godzilla (2014); Transformers: Age of Extinction (2014); Toy Story (1996 - onwards); Jurassic World (2015); The Good Dinosaur (2015).

So, are dinosaurs as useful as we think for outreach purposes?

The points raise a simple but significant question: how effective is dinosaur-based outreach, really? As noted above, many decisions about outreach are shaped around dinosaur science and resources are poured into promoting dinosaur science itself. But are we right to regard dinosaur outreach as highly as we do?

Trying to balance the positive and negative points raised above, my take is yes, dinosaurs are an effective means to bringing science to people… but probably only certain people. Specifically, they seem to work very well among those who are already tuned into palaeontology, natural history and general science, an audience composed mostly of adult enthusiasts and children. Beyond this, their effect seems to tail off quickly and they may actually be a barrier to effective outreach. Audiences with preconceived expectations of dinosaur-themed content may ignore anything dinosaur related, which is a concern with us giving dinosaurs such privileged consideration in educational material. Are we limiting our promotion of other topics that could engage these uninterested people? And is one of our challenges of popularising palaeontology making dinosaurs and related topics universally attractive, and not just subjects with appeal to specialist audiences or younger people?

Of course, your opinion on this matter may differ. But even so, I think most of us would agree that our wider education about dinosaurs and related matters could be more effective, or at least more nuanced and reflective of more topics, than it currently is. I am optimistic that a groundswell of suitable movements towards this goal may already be underway. Many modern curators, scientists and artists are attuned to matters of science communication and interested in identifying outreach issues, sharing best practise, evolving public engagement methods and reaching new audiences with new topics. The fact that this article is being written as output from a workshop dedicated to popularised palaeontology is evidence of these practises actually occurring, and it feels like the right questions are being discussed. How can we, and when should we, shift focus from dinosaurs? How do we make other forms of life/parts of museum collections of wider interest? How do we more effectively impart new science to publishers, movie makers and other non-educational bodies making palaeontologically-themed media? It’s also pleasing to see more discussions about the once largely backgrounded industry practises of palaeoartistry in both scientific and popular media. Realising the important role that palaeoart has for communicating science, many involved in its production are vocally distancing themselves from the ‘popularised’ image of dinosaurs to more nuanced, scientifically-validated and interesting portrayals of dinosaurs, as well as other forms of prehistoric life. We are still on the uphill part of this journey to revising our outreach approach, but it’s reassuring to know that a body of professionals are looking critically at dinosaur outreach and its wider impact.

Minor victories in recent palaeontological outreach involve effectively communicating to certain, interested audiences that Deep Time was not a dinosaur theme park, and that fossil creatures did not spend all their time battling and roaring at one another. Evidence that this message has hit home with at least some audiences is reflected in the broadening depth and nuance of palaeoart being posted across the internet. Shown here: my take on Jurassic stem-mammals, a gorgonopsian, gliding drepanosaurs, a goniopholidid crocodyliform, Cretaceous albanerpetontid, erythrosuchids, and... Longisquama, whatever the heck that is. Not shown here: dinosaurs in premier view, or roaring. The challenge is getting scenes like this, and subjects like this, to wider audiences.
Most of the discussions and innovation in dinosaur/palaeontolgical outreach are taking place online, and transferring these to ‘real-world’ outreach, where the necessity of resource investment makes change risky, may be our greatest upcoming challenge. Again, however, there are signs of this sort of thing happening, such as the famous (or infamous?) decision to replace the Natural History Museum’s famous Diplodocus cast with a blue whale skeleton. This logic of moving this famous attraction has been questioned by some, but I admire the museum for putting a very relevant and symbolically significant specimen in their most prominent location. In doing so, they’re making a clear statement about what they consider to be important, and what they want the public to engage with. Whether you agree with the controversial reorganisation of the natural history museum or not, the idea of outreachers taking initiative with their educational agenda is something I feel we should echo when popularising prehistoric animals. If our outreach is primarily reaching pre-interested audiences anyway, then why not have faith in their interest and tell them what we - as researchers, artists and curators - think is fascinating and exciting about our field, whether it’s related to dinosaurs or not? It would seem a diverse array of outreach topics is more likely to spread out from palaeo-primed audiences and into broader public interest than one largely revolving around a single, perhaps somewhat over-familiar topic. Perhaps cutting palaeontological outreach’s umbilical chord with dinosaurs would benefit us outreachers too, allowing us to freshen and rethink our approach to popularising neglected groups and focus on their own selling points, instead of using them to greater contextualise dinosaurs.

The risk of failure is what prevents many of us, and our employers, from straying too far from tried and tested means of outreach. And yes, if we’re talking paleontology with the public, dinosaurs are an obvious safety net. But we should take advantage of the fact that we’re more enabled than any previous generation of educators to cooperate, create and promote the subjects we feel are important with only a little inventive thinking and technological knowhow. Individuals can now develop significant outreach resources without the need for expensive designers and developers; online promotion can be essentially free; and the increasing accessibility of printing - both 2D and 3D materials - is lowering the financial risks tied into ‘real world’ outreach events. Any public enterprise involves a level of investment and risk, but resourceful thinking and shouldering the brunt of development ourselves can minimise these.

In closing, I want to stress that I’m not wailing on dinosaurs. As may be evident from my own output, I think they’re fantastically interesting animals with an important role to play in outreach. But for dinosaur outreach to be successful and support, not restrict, other outreach efforts we have to realise their limitations, as well as their strengths, as public ambassadors.

This piece of outreach was supported by Patreon

The paintings and words featured here are sponsored by folks who are certainly very popular in my house, my Patreon backers. Supporting my blog from $1 a month helps me produce researched and detailed articles with paintings to accompany them, and in return you get access to bonus blog content: additional commentary, in-progress sneak-previews of paintings, high-resolution artwork, and even free prints. For this post we'll be looking at my new angry nodosaur painting, discussing ankylosaurs in palaeoart and why they're so darned challenging to render well. Sign up to Patreon to be part of the discussion!

Reference


  • Ross, R., Duggan-Haas, D. and Allmon, W. (2013). The posture of Tyrannosaurus rex: Why do student views lag behind the science? Journal of Geoscience Education, 61, 145-160


Wednesday, 2 November 2016

The blog post where I ask myself “should we make Plateosaurus fluffy?”

Plateosaurus engelhardti restored as a) speculatively filamented and b) speculatively smelly (note the cloud of insects buzzing around its head). Scientists have good reason to think that sauropodomorphs could not be routine shower users, but what about that fuzz?

PS - Blogger has added some weird watermark on this picture that I can't figure out how to remove. If anyone knows, please let me know! 


Palaeoartistry is not a science. Even a conservative reconstruction requires artists to stretch data and evidence further than would be allowed for any scientific study and the whole process relies more on inference and speculation than many of us would like to admit. Yes, palaeoart is data-led and evidence-based, but only in rare circumstances do we have enough data to bring us to a single, reliable interpretation of a fossil species. Most of us would agree that there are some aspects of reconstructions that we can and should be getting 'right' for many species - basic proportions and musculature being top of the list - but beyond these science can often only narrow our choices, not present definitive answers. In lieu of clear scientific guidance, what guides these decisions may be our personal preferences, logical thinking, the demands of a project, or the penchants of our consultants. This means that, odd as it may seem, vastly contrasting reconstructions can be construed equally credible. A weird, alternative take on a fossil species might be just as ‘accurate’ to our knowledge as another preferred or familiar one. When evidence is equivocal for two or more states, we have to concede that one interpretation can be just as 'correct' as another.

With this in mind, I thought it might be pertinent to talk about the above reworked reconstruction of Plateosaurus engelhardti with a filamentous coat, and why – at time of writing at least - it’s perhaps neither ‘right’ or ‘wrong’ to depict this animal in this way. I could have covered it with scales as an alternative and not necessarily been ‘correct’ or ‘incorrect’, either. The question of whether sauropodomorphs were wholly scaly has not escaped discussion in many quarters - it was even mentioned at this blog briefly back in 2013 - so, for a change, and perhaps to mirror the sometimes antagonistic way that similar matters are discussed on social media, I’m going to present my thoughts here as a conversational debate between… myself. The idea is that it will allow for fuller discussion of opposing points, but I suspect it really just reflects the amount of time I spend alone at home with no-one but some chickens and various squamates for company. Whatever, hopefully the 'conversation' below will be balanced: both ‘pro-filaments’ and ‘pro-scales’ have important points to make, and I’m not strongly advocating one or the other here: the point is that both sides have valid points to make, so warrant an equal platform. Over to, er… me, then.

Me¹, meet Me²

Me¹ (filaments, opening statement). Should we restore Plateosaurus and other sauropodomorphs with filaments? Maybe. The evolution of dinosaur integument is an increasingly complicated area of study, and the idea that scales alone were the most likely ancestral condition for the major dinosaur lineages is no longer certain. As is well known to many, in the last decade we’re discovered filaments occurring in not only theropods but also in disparate parts Ornithischia too, and detailed new studies are suggesting that filaments in the likes of Psittacosaurus are structurally similar to those of other ornithischians as well as extant and extinct theropods (Mayr et al. 2016). They may even be similar enough to suggest true homology (Mayr et al. 2016), which strongly implies dinosaur skin may have been at least partly fuzzy in its ancestral form. Indeed, with pterosaurs thrown into the mix as well, an ancestrally-filamentous Ornithodira remains not only a valid hypothesis, but one that has passed several important tests in recent years. This being so, a filamented Triassic sauropodomorph is a sensible extrapolation of modern data.

Me² (scales, opening statement). Should we restore Plateosaurus and other sauropodomorphs with filaments? Maybe not. Firstly, studies have shown that our reconstructions of the ancestral ornithodiran integument type remains highly sensitive to the condition of its basalmost species, and we lack fossil data on these forms (Barrett et al. 2015). The 'ancestrally filamentous hypothesis' is enjoying some invigoration from new discoveries and research, but the game is not over yet. Virtually all of our dinosaur skin samples stem from derived species that had plenty of time to modify their integument from the primitive condition, and we have to concede that - whatever we think about the ancestry of dinosaur skin - they were very plastic in integument types. Thus, an important test of this hypothesis will be the recovery of good fossil skin samples from Triassic dinosauromorphs and pterosaurs, and their close relatives. Until we find these, or a fuzzy sauropod fossil, the recovery of scales from all three major dinosaur clades means the argument for 'ancestrally scaled' remains valid.

What's the likelihood of sauropodomorphs having filamentous structures on their skin? Not much, according to Barrett et al. (2015), even in models where dinosaurs are given their best chance of being scaly. But does the absence of skin impressions from non-sauropod sauropodomorphs come into play here?
Secondly, accepting that the evolution of dinosaur integument is complicated, sauropodomorph skin impressions are exclusively scaled. With our current data we can’t say whether this is a derived, reversed condition from a filamentous ancestor or retention of a ‘primitive’ scaled skin type, but whatever: all evidence we have from the sauropodmorph branch of the dinosaur tree seems to show scales. Granted, these specimens all pertain to true sauropods, not their ancestors, but as the closest relatives of Plateosaurus we should probably be using these as guides for our reconstructions. This is supported by the probability study of Barrett et al. (2015), who calculated that sauropodomorphs only have a slim chance (<10%) of non-scaly skin, even when the likelihood of filaments in Ornithodira was maximised.

Me¹. Three points in response here. Firstly, admittedly playing Devil’s Advocate, a <10% chance of sauropodomorphs being filamented is still a chance, right? A filamentous Plateosaurus may not show what is most probable, but it still shows something that science shows is ‘possible’.

Secondly, and more constructively, the fact that skin impressions are not known outside of true sauropods means we may want to question what that the sauropodomorph stats of the Barrett et al. (2015) study really tell us. Does it reflect the condition for all sauropodomorphs, or just Sauropoda? The same probability assessments gives a 50% chance of filaments being ancestral to Saurischia, so the the first sauropodomorphs must have a somewhat higher chance of being filamentous, or at least being closely related to filamented species. Presumably, that 50% chance of filaments doesn’t just plummet the moment we steer evolution to the sauropod line: it’s a long evolutionary road from a basal saurischian to the sorts of sauropods we have with skin impressions, and we have no idea if or when filaments were abandoned on that road. We have a data vacuum of skin at the base of Saurischia: after sauropods, the next closest saurischian with skin impressions to Plateosaurus is the abelisaurid theropod Carnotaurus - hardly a close relative at all. Our absence of skin impressions around the phylogenetic neighbourhood of Plateosaurus, and our data about the likelihood of filaments in saurischians as a whole favours open-mindedness about the life appearance of these animals.

The third point is that if recent claims about dinosaur filament homology are correct, we have to assume that these structures were present in some form in the stock that gave rise to all major clades. Seeing as theropods retained filaments after the theropod/sauropodomorph split at the base of Saurischia, we should probably assume that sauropodomorphs lost their filaments after that divide. If so, a fuzzy Triassic sauropodomorph is not a far stretch.

Me². But - even assuming homology of filaments - if Carnotaurus is scaly, and so are sauropods, we can contrarily hypothesise that saurischians were secondarily-scaly ancestrally. This might even be the most objective reading of the data we have.

Me¹. Perhaps, but is the data supporting that interpretation really reliable? Carnotaurus is actually a weird outlier among theropods, it being the only theropod known with extensively scaly skin impressions. We have to wonder how significant this is against the wider backdrop of extensively filamented coelurosaurs sitting just a little higher up the theropod tree. As the rootward-bracket of the theropod integument bracket it's almost irritatingly important - it has a lot of sway in our reading of dinosaur integument evolution - but we still have to view it as a single outlier against the wider picture of theropod integument. As with any outlier, we have to be cautious about over-interpretation, or thinking one datum can give us the whole picture. As with so many palaeontological issues, we need more information.

The ornithodiran integument evolution 'choose your own brackets' game. When clades without skin samples are featured alongside those with them the amount of missing data becomes apparent, and trying to find obvious patterns becomes tricky. Osteroderms are considered evidence of scales because of their relationships with scaly coverings in modern animals. Half-boxes represent doubtful records of true feathers. Compiled from various sources - thanks to blog commenters for pointing out some omissions in a previous version.
And if we need an example of how sensitive our dataset still is, we need only consider Psittacosaurus, Kulindadromeus. Both are deeply nested within Ornithischia but basal to clades dominated by scaly species, and yet both have filaments. No-one would have predicted their integument type from their relatives. Not only does this show that our data may not be reliable enough yet to make confident predictions about integument types, but it suggests skin types might have been quite a bit more varied among even closely related dinosaurs than we anticipated.

Me². The risk here is that we’re pandering to exceptions, unknown data and slim chances. Arguments about the unknown nature of sauropodomorph or early saurischian skin seem like threading loopholes more than effective rebuttals. They play on what we don’t know rather than what we do, and that’s not how science works. There’s lots to be said for keeping an open mind, but we shouldn’t ignore data. Sure, there’s room for doubt here and we may be proved wrong in the future, but palaeoart should probably err on the side of caution, using the best supported, highest probability models to inform reconstructions. ‘Being wrong for the right reasons’ is perhaps the motto we should take when faced with the data gulfs associated with restoring partly known animals.

Me¹. The flip side of this is that ornithodiran integument has been proved complicated and surprising often enough that assuming variation in the poorly known areas is justified. Who expected Kulindadromeus and Psittacosaurus, or Tianyulong? Who, for that matter, would have predicted the first fluffy pterosaur fossils among - at that point - entirely scaly relatives? The point about exploiting unknown data is an important one, but we have a strong precedent for filaments in poorly sampled areas of ornithodiran evolution now. This is less exploiting a loophole than admitting we don’t have a full picture yet, and simply portraying one of the two more likely options of integument form.

Furthermore, Kulindadromeus and Psittacosaurus are great examples of how dangerous our approach to integument reconstruction is when we only have scraps of soft-tissue. It’s only because of their extensive soft-tissue preservation that we know they mixed scales and filaments in different body regions. And it’s not just these dinosaurs that show us that. Pterosaurs have scaly feet to counter their fluffy bodies (Frey et al. 2003), and the extinct mammal Spinolestes is known to have had scales, bristles, and variably long and short fur (Martin et al. 2015). Andrea Cau has even cast doubt on our presumed reasonable knowledge of Carnotaurus skin, pointing out that its skin impressions all pertain to the underside of the animal and that the dorsal surface could be entirely different. We thus have to ask what we really know about sauropod skin: are the bits we have representative of whole animals, or the group as a whole? The most extensive set we have - those from a diplodocid that might be Kaatedocus, described by Czerkas (1992) - show a lot scaling on the body, which meets the predictions we’ve made from smaller pieces of skin found with other sauropods. But it might be naive to think this offers a significant insight into these species, or rules out the chance of localised filaments on some sauropodomorph species.

Me². But where do we draw the line here? There has to be a point where we can say ‘we haven't seen evidence of filaments yet, and we should factor this into our science’ without someone going ‘you don’t know the whole animal yet!’. Some artists take this to an extreme, restoring animals like Edmontosaurus with large filamented regions despite this species being known from several well-studied and extensively-scaled mummified individuals. These have no evidence of filaments whatsoever, despite preserving scales down to millimetre resolution, and yet some folks are still unconvinced, speculating that filaments were poking through gaps between scales and so on. Palaeoart like this Plateosaurus reconstruction almost holds palaeontology to a standard of knowledge that it’s unlikely to ever attain: no, we don’t have skin impressions from every species, we don’t have good skin impressions from many species at all and fossils are never perfect records of animal appearance. But we have to use what we have: science does not work on a philosophy of 'assume whatever until proven otherwise'.

Excellent fossils show that animals like the Cretaceous mammal Spinolestes xenarthrosus had regionalised integument variation, just like modern species. So how much skin do we need from a fossil animal before we can rule out major variation in integument types? Note that the tail fluff in this picture is speculative - the integument preservation of Spinolestes doesn't extend to the tail region.
Me¹. Of course, if we restore animals however we like in our artwork then we’re not doing real palaeoart, just palaeo-based artwork. Palaeoartists must constantly ask where the boundary between informed, sensible extrapolation of data ends and where unbridled speculation begins. So I suppose the question here is ‘does this reconstruction go too far?’ Is a filamented Plateosaurus just nutball craziness, or a reasonable idea based on what we currently know? The fact this discussion has got this far suggests that there must be some validity to this idea, even if some might think it's ultimately a flawed one. But 'flawed' is not the same as 'nonsense'. Depictions of filamentous or scaly sauropodomorphs simply reflect emphasis on different datasets. A scaly interpretation prioritises skin impressions from close relatives, but downplays emerging 'bigger picture' interpretations of ornithodiran integument, and a filamentous one does the opposite. From a 'big picture' perspective we're entering a time when reconstructing any dinosaur with filaments should not be considered ridiculous or outlandish, save for those with well sampled scaly skin tissues. It's not necessarily the best approach, but it's not an invalid one.

Me². It must be said that it would be easy to construct this conversation around a scaled version of this animal, and discuss why it doesn’t have filaments. Our base expectation for dinosaur integument and life appearance is in a state of flux, no matter what we personally prefer or assume.

Me¹. I think a point often lost on viewers of palaeoart is that these artworks are not, and cannot, be definitive, incontrovertible renditions of these animals. There are some animals so well represented in fossils that they lend themselves well to ultra-detailed reconstructions which are hard to quibble over to significant degrees - the awesome Bob Nicholls Psittacosaurus model being a great example (Vinther et al. 2016) - but for lesser known animals like Plateosaurus we are only painting hypotheses, not fact-based reality. This painting is one possible reconstruction of Plateosaurus as known in 2016, a time when interpretations of dinosaur skin evolution remain in flux. Time will tell if it's the product of over-interpretation of fossil data, or a lucky gambit later borne out with fossil evidence. I don’t mind getting stuff like this wrong: I’m more interested in painting and exploring credible possibilities of what we know now, not being ‘right’. We may never know what is ‘right’, so there’s not much point worrying about it. There are a couple of essays on this topic in my new book, Recreating an Age of Reptiles (Witton 2016).

Me². You’ve seen RecARep? I hear it’s awesome and that everyone should buy a copy.

Me¹. Wow, that’s desperate. Any actual final points?

Me². In a previous post on the role of pterosaurs in interpreting dinosaur filaments I concluded that: “Forcibly arguing for either scales or filaments at the base of Dinosauria seems premature at this stage, and, whatever our personal hunches are, it seems sensible to accept some ambiguity in this situation for now.” I think that’s true here too. There are certainly arguments to be had on both sides, some stronger than others, but neither side has knock-out data or evidence on the table yet. It’s the same old frustrating cop-out, but we need more fossils, and fossils of the right sort, to resolve this. Specifically, we need early saurischians or dinosauromorphs with good skin preservation, as well as that Triassic sauropodomorph with excellent skin remains. It must be said that these animals are not generally found in fossil Lagerstätten conducive to good soft-tissue preservation, so I’m not advising anyone to hold their breath for this one. But new techniques for detecting soft-tissues and increasing awareness of soft-tissue preservation in lithologies once thought to only preserve bone are reasons to be optimistic that we'll have insight on these matters one day.

Me¹. And ‘frustrating’ is the right word here, too. It seems like dinosaur science has made sufficient headway on understanding integument evolution and predictive methodologies that a reasonable, if provisional answer to the ancestral integument of the three major clades is close. But the puzzle piece needed to get our first good look at the broad picture is still out of reach.

Awkward facial expression, bad fashion sense and a hygiene problem. No wonder no-one likes to paint early sauropodomorphs.
Me². OK, that seems like a point to end. This discussion with yourself didn't seem to go too bad, actually. Unlike that vulture-like ruff around the base of the neck in the Plateosaurus reconstruction. I mean, if you're going to paint a controversial reconstruction, at least make the animal look good.

Me¹. Pfft... Good… bad… I’m the guy with the graphics tablet.

Me². Movie quotes in scientific blog post don’t make you look clever, you know. You just cheapen the whole act.

Me¹. There is no fate but what we make for ourselves.

Me². What...? that doesn’t even fit our context.

Me¹. It wasn’t the airplanes. It was beauty killed the beast.

Me². Sigh, why do I hang around with you? I think we're done here.

So long everyone - I'm away from my computer for the next few weeks so I'm going to be pretty quiet in blog comments, social media and so on. Things will pick up again come December when we'll be addressing the sauropods in the palaeo-outreach room: has the popularity of dinosaurs above other fossil animals become a problem?

This blog post was inarguably supported by Patreon

The paintings and words featured here are sponsored by an excellent group of animals with regional variation in integument, Patreon backers. Supporting my blog from $1 a month helps me produce researched and detailed articles with paintings to accompany them, and in return you get access to bonus blog content: additional commentary, in-progress sneak-previews of paintings, high-resolution artwork, and even free prints. Later this month (much later - around the 28th/29th) I'll be uploading a video version of the presentation I gave over the Halloween weekend at Dinosaur Days 2016, entitled Palaeoart and the Never-Ending Quest for Accuracy. Here's the title slide to whet your appetite:
"Oh, I see you're putting movie easter eggs in this post now too. This is why no professional blogging platform will pick you up."

Sign up to Patreon to get access to this and the rest of my exclusive content!


References

  • Barrett, P. M., Evans, D. C., & Campione, N. E. (2015). Evolution of dinosaur epidermal structures. Biology letters, 11(6), 20150229.
  • Czerkas, S. A. (1992). Discovery of dermal spines reveals a new look for sauropod dinosaurs. Geology, 20(12), 1068-1070.
  • Frey, E., Tischlinger, H., Buchy, M. C., & Martill, D. M. (2003). New specimens of Pterosauria (Reptilia) with soft parts with implications for pterosaurian anatomy and locomotion. Geological Society, London, Special Publications, 217(1), 233-266.
  • Martin, T., Marugán-Lobón, J., Vullo, R., Martín-Abad, H., Luo, Z. X., & Buscalioni, A. D. (2015). A Cretaceous eutriconodont and integument evolution in early mammals. Nature, 526(7573), 380-384.
  • Mayr, G., Pittman, M., Saitta, E., Kaye, T. G., & Vinther, J. (2016). Structure and homology of Psittacosaurus tail bristles. Palaeontology. doi 10.1111/pala.12257.
  • Vinther, J., Nicholls, R., Lautenschlager, S., Pittman, M., Kaye, T. G., Rayfield, E., Mayr, G. & Cuthill, I. C. (2016). 3D Camouflage in an Ornithischian Dinosaur. Current Biology, 26(18), 2456-2462.
  • Witton, M. P. (2016). Recreating an Age of Reptiles. Red Phare.