Sunday, 19 October 2014

Dorygnathus tweets its way through development

For various - and mostly good - reasons, there's not been much chance for blogging of late, but the upside is that I have a lot of new art, discussion and science to share in the near future. In the interests of not completely abandoning the blog in the interim, here's a series of Tweets posted over the last two days documenting work on a painting of the Early Jurassic pterosaur Dorygnathus banthensis. I can't say too much about the painting at this stage, because it's earmarked for an upcoming project and its context will be best explained there. Still, there's no harm in leaving a few notes about the restoration and painting process, so here goes...

The initial digital sketch, complete with Kevin Padian's (2008) Dorygnathus skeletal reconstruction in the top corner for basic guidance. Padian's (2008) work was my principle reference here, and is probably the go-to paper for all things Dorygnathus. Those of you who know a bit about pterosaur research may be aware that Kevin was the main, and rather vocal, proponent of pterosaur bipedality in the 1980s and 1990s, so may be surprised to see his name attached to a quadrupedal pterosaur skeletal. Kevin is now on board with the consensus view that pterosaurs were primarily or exclusively quadrupedal animals, although he still argues that bipedality was essential for rapid terrestrial locomotion. I don't really agree with him, but that discussion will have to wait for another time.
A little rotation of the underlying sketch, some basic outlines of the background complete the overall composition. I've had this image knocking about my brain for about a week now, and think the layout is a fairly good approximation of what I've been imagining. This painting has a message to deliver about the sprawling posture of the animal, and I think this composition demonstrates that well enough. There is a lot of compelling anatomical evidence that Dorygnathus and many other non-pterodactyloids could not adopt erect forelimb postures, which is partly why they're considered inferior terrestrial animals to pterodactyloids. But is that the case for all non-pterodactyloids? I'm saying nothing else at this stage, other than that this painting has a contrasting sister image.

A lot more detail by the end of day one. The eye was shrunk to fit the orbit a little better, and the animal now looks generally larger as a result. This is good: Doryngathus is about 1.8 m across the wings, so needs to look seagull-sized. The basics of the colour scheme are added now too. There's a lot of evidence that rhamphorhynchines* like Dorygnathus were seabird like in their habits, so it makes sense to use common seabird colours - whites, greys, blacks and - here. There's a butt-tonne more detail here than I'm used to working with, the result of a big upgrade to my painting hardware and software. A graphics tablet built this decade? Imagine that!

*I don't really agree with Bennett's (2014) proposal that Dorygnathus is a scaphognathinid/ine/whatever. Ah, non-pterodactyloid pterosaur taxonomy: what a mess.

Lots of laminae - fine scaling bedding - in the rock here. Got to put that training into sedimentology to use somewhere.

Nearly there by this stage. Note the similar dip-direction on the rocks jutting out into the sea. Their angle means we can have a few splashy waves here and there, which is nice, and you could map the geology of this bay quite effectively. Because if you had a time machine and visited the Jurassic, mapping grey rocks would totally be the thing to do.

And done. The only real differences between the last two images are some tidier shading, a few background Dorygnathus and some splats of guano on the hero rock. I've long thought that locations supporting lots of pterosaurs would literally be a bit crappy, but never put it into art until now. I expect their guano looked a lot like that of birds and other reptiles: a mix of white, pasty stuff and darker gunge. Nice.

OK, time at the blog. Sorry for the short post, but I may have some good news soon for anyone interested in buying prints of my stuff - just in time for Christmas! I'll leave you with a larger version of the image than the low-res versions afforded by Twitter.

Dorygnathus banthensis at the coast, surrounded by the filth of its contemporaries.


Reference

  • Bennett, S. C. (2014). A new specimen of the pterosaur Scaphognathus crassirostris, with comments on constraint of cervical vertebrae number in pterosaurs. Neues Jahrbuch für Geologie und Paläontologie-Abhandlungen, 271(3), 327-348.
  • Padian, K. (2008). The Early Jurassic pterosaur Dorygnathus banthensis (Theodori 1830). Special Papers in Palaeontology 80: 1-64.

Monday, 29 September 2014

'Support Original Palaeoart': we take it to the mainstream

The industry of reconstructing extinct animals in illustration, sculpture and animation - we all know it as 'palaeoart' - is a paradoxical place. One the one hand, there is more demand for palaeoart than there ever has been, increasing recognition of the role of palaeoart as a scientific and outreach tool and, because of the internet, more interesting and thought-provoking palaeoart being produced than ever before. This would make it seem that palaeoartistry is a flourishing, economically viable and interesting place to work within. On the other hand, much of our widely published, well-paid and/or high profile palaeoart work is rife with plagiarism, is creatively stagnant, has limited commercial appeal and presents gross inaccuracies to the fossils it is meant to represent. Given the elevated public influence and larger economy of these high profile artworks, it might be argued that this less interesting, ethically-questionable and scientifically dubious side of palaeoart overrides the independent sphere as the current 'status quo' within the palaeoart industry.

These issues are not new: since at least the late 1990s, artists and palaeoart aficionados - including well known artists like like Bob Walters, Tess Kissinger and Gregory Paul - have made noises about generally poor working practises in palaeoart and called for change - sometimes in radical ways. However, most of this commentary has been published in esoteric online venues with limited prospects for reaching those involved in palaeoart production. Moreover, because these discussions have taken place in online forums, mailing lists and blogs rather than more 'officious' venues such as magazines or journals, they may be largely discredited or ignored by those who only have time for 'real' literature appearing in mainstream venues. This is a genuine and relevant problem: many scientists - including individuals involved with the production of palaeoart - see little value in the online palaeontological community or the opinions it expresses.

Today, Darren Naish, John Conway and I are attempting to bring the problems within the palaeoart industry into the light via an open-access commentary piece at Palaeontologia Electronica. We hope that by publishing this piece at a respected online venue that it will be more visible and credible to the academics and financiers involved in palaeoart production, and help stimulate the discussion needed for changes desired for years. Much of what we cover in our article will be familiar to regular denizens of the online palaeontological community. We outline why we think palaeoart is important (its long history, importance to science and the millions dollar industries it underpins); what we think is sour with modern working practices (that copied, objectively inaccurate art forms the majority of high profile/commercially produced art, while truly original and progressive artists are overlooked and sometimes deliberately ignored) and what we think can be done about these issues (artists being more circumspect about their trade; palaeontologists being more prudent in their consultancy roles; and art patrons improving their knowledge of and financial approach to palaeoartistry). There's a lot more to say on each of these issues, but I do not want to simply rewrite our article here: head to PE or download the pdf version for more details. There are a few comments and questions I want to nip in the bud, however:

The money issue

Yeah, we suggest artists take a firmer line about their costs. Cue comments about dictating industry workings, comparison to infamous 2011 Greg Paul palaeoart debate, etc. But look at what we say carefully: we encourage artists to be more realistic with their costs beyond a certain career stage, and we give no opinion on what their art should cost. We suggest working standards will improve if folks who've proven their palaeoart mettle, and are 'getting serious' with their palaeoartistry, appreciate that their work is worth something. Of course it is: it takes hours or days or research and labour to make. We should be proud of that, and not undervaluing it. Ultimately, palaeoart will continue to be treated as a disposable commodity - a point we make time and again - until the collective producing it makes it worth something to those buying it. There's a lot more to say on this point, so please read what we say over at PE before leaping to the comments box below.

So, palaeoartists need to be cold, heartless businessmen now, right?

No: we just arguing that there needs to be greater respect all round for the palaeoart trade. Like any industry, there will always be room for personal favours, 'mates rates' and that sort of thing, but these should be exceptions, not the standard. We're not asking for people to be inhuman, or trying to take the enjoyment out of producing palaeoart, only for standard business practises to be more routinely applied to palaeoart production and financing.

You guys are hypocrites. You've asked for/given free art, for instance, and been involved with products featuring awful palaeoart

Yep. Like all human beings, we're a mess of hypocrisy and mixed-messages, and we fully admit to being associated with behaviour which we suggest is detrimental to palaeoartdom. However, we can also honestly say that we try to implement our 'best practises' where we can. Darren, for instance, pushes for using independent artists wherever he can in his books and articles, and fights for payment for image use. Both John and Darren (along with Memo Koseman) have been important voices in the call for more interesting palaeoart with the publication of All Yesterdays (Conway et al. 2012). John has also outlined earnings for his art and explained how, realistically, art needs to be costed to make a living from it. Given the cultural taboo associated with declaring earnings and salaries, that's a bold but important set of figures to release to the public. Along with John and Darren, I do my best to promote excellent palaeoart, work genuinely hard in my consultancy roles, and endeavour to strike realistic costs with my patrons (it's been a long time since I've done art for free, for instance). We're not always successful in these bids, but we push hard wherever we can for the better standards we would like.

I don't see a recommendation for any 'good' palaeoartists in the article. Who do you recommend?

We each have our favourite artists - modern artists who do great work, past artists who broke new ground and so forth - but we have deliberately avoided promoting any services in the PE piece, including our own. The only artwork featured therein are a few incontrovertibly classic pieces of vintage palaeoart or modern works used to make specific points (e.g. John's reptile cat from All Yesterdays, which we use to mirror the inaccuracies present in many modern palaeoartworks). We want people thinking more about what makes palaeoart good and bad, and using their own research to make informed decisions about palaeoart services. Stating who we think are the 'best' artists conflicts with that message.

So what can we do?

Regular visitors to this blog or related works may have seen this image knocking about in various posts:

From Witton et al. (2014).

This is actually a figure from our article, and is our way of making it easy for you - a member of the palaeoblogosphere - to promote this cause. The three elements listed along the bottom touch on the cornerstones of our arguments:
  1. Accuracy: adherence of palaeoart to fossil and biological data; realistic depictions of contemporary palaeontological hypotheses; excellency in consultancy
  2. Creativity: ending of the widespread issue of palaeoart plagiarism and the production of meme-worthy art; promotion and appreciation of artwork and individuals who bring new perspectives and insights to the depiction of extinct animals
  3. History: appreciation of palaeoart as a 200 year old institution with its own important fashions, movements and individuals; realisation that the 'when, where and who' of palaeoartworks are as important as the artworks themselves
We want our graphic on blogs, articles, videos and even conference presentations as a means of promoting these issues as widely as possible. Remember that the whole reason for writing the Palaeontologia Electronica piece was to break these issues out into the wider world. The way to do that is through promotion in as many places as possible. We want it Facebooked, Tweeted, blogged, Tumblr'd and whaever else you can do on social media. We want it on respected, widely-read websites so those who don't frequent the depths of the palaeoblogosphere can't avoid it. We want SVP 2014 audiences seeing this in so many presentations that Berlin erupts with discussion of 'what's with all those palaeoart logos?'. However you do it, we're simply asking for a bit of a fuss. Ultimately, we want this widespread enough that the folks involved in palaeoart production can't ignore it, and will hopefully start thinking about palaeoartistry and its practitioners with the respect they deserve.

That's enough from me on this: head to Palaeontologia Electronica for more. Again, if you agree with what we're saying, please help us promote this widely and, if you're in the lucky position to be influencing palaeoart projects, please consider what we're saying here especially carefully.

References

  • Conway, J., Kosemen, C. M., & Naish, D. (2012). All Yesterdays: Unique and Speculative Views of Dinosaurs and Other Prehistoric Animals. Irregular Books.
  • Witton, M. P., Naish, D. and Conway, J. (2014). State of the Palaeoart. Palaeontologia Electronica Vol. 17, Issue 3; 5E: 10p;

Friday, 26 September 2014

Does Deinonychus really have one of the most powerful bites of all dinosaurs?

Quick sketch of Deinonychus antirrhopus with expanded, bone-puncturing jaw muscles, a requirement of having a bite as strong as a modern alligator. Say what? Read on...
There's a part in Michael Crichton's Jurassic Park novel where Velociraptor attempt to bite through bars to reach a people-shaped lunch. Presumably, they're meant to give readers something to rally behind seeing as one person in the line of fire is Ian Sodding Malcolm - I'd be chewing through steel too if it meant we could enjoy a few moments without another preachy monologue. Crichton describes them as hyena-like in their ability to bite through steel, delivering thousands of pounds of pressure per square inch and gnawing their way through thick metal bars in 15 minutes.

Dromaeosaurids biting through steel bars - heck, any animal biting through steel bars, including hyenas - intuitively sounds like crazy talk*. But was Crichton at least right about the strong bites of dromaeosaurids? I've been doing some investigating on dromaeosaur jaw muscles for a new palaeoart commission, but I've come unstuck. Here's why.

*Is there any substance to claims about modern animals biting through steel? Given that tooth enamel is only very slightly harder than straight steel, I wonder how long teeth would last when gnawing through anything but the thinnest metal sheet.

Recently, Gignac et al. (2010) presented a suite of bite marks on Tenontosaurus bones argued to show Deinonychus as capable of deeply puncturing bone with powerful bites. The tooth gouges match those of large Deinonychus in many aspects (bite mark size, shape, correspondence with dental arcade) and broken teeth associated with the same Tenontosaurus corroborate suggestions that Deinonychus fed from the carcass. Other teeth, not from Deinonychus, were also at the site, but their owner does not seem to have left any other obvious traces. Experiments with modern cow bones suggest Deinonychus needed a whopping 8200 N to puncture Tenontosaurus bones to the degree seen in the fossil remains. This value puts Deinonychus bites on par with those of adult alligators and leaves hyenas in the biomechanical dust. It also grants Deinonychus one of the highest estimated bite forces of any dinosaur, even greater than animals of much larger size. The tooth marks only match the largest known Deinonychus individuals, possibly indicating that juveniles were incapable of delivering such bite forces. Because Deinonychus puncture wounds are rare, Gignac et al. argue that puncturing bones was not common in Deinonychus, and that their powerful bites were primarily used for aggressive behaviours instead.

Bitemarks in the radius of Tenontosaurus specimen FMNH PR 2261, below, compared to the dental arcade of Deinonychus antirrhopus, above. This is one of many pathologies on FMNH PR 2261, almost all of which have been attributed to Deinonychus feeding behaviour. From Gignac et al. 2010.

For artists, Gignac et al.'s paper has important implications. Generating 8000 N of bite force requires a lot of muscle, so we might predict that Deinonychus jaws had the same swollen jaw muscles of modern crocodiles to generate all those bone-smashing newtons. This is at odds with other reconstructions of Deinonychus, where the jaw muscles do not atypically alter the contours of the face. I don't know how visible expanded, crocodile-like jaw muscles would be on deeply feathered maniraptorans, but reconstructions with sparse or naked faces would certainly need to take this on board. I've had a quick play about with this concept in the conservatively feathered Deinonychus above.

Problem is, Gignac et al.'s conclusions are not uncontested. Biomechanical assessments of Deinonychus jaws have found they were mechanically weak and ill-suited to delivering powerful bites (Therrien et al. 2005; Sakamoto 2010; Fowler et al. 2011). Therrien et al. (2005) estimated Deinonychus bite force at a relatively wimpy 15.7% of alligator jaw power, which Gignac et al. translate into 1450 N. This isn't unimpressive - as strong as that of a 30 kg wolf - but a far cry from an alligator-like bite, and certainly deflates our reconstructed jaw muscles to their traditional size. On the face of it, I certainly find the arguments for weak jaws more convincing. Hyenas and alligators have robust, wide and solidly-built skulls with generous room for jaw muscle placement, whereas the skull of Deinonychus is full of holes, is relatively narrow and slender, and with comparatively little room spaces jaw for muscles.

So, what to do? Jaws with relatively small muscles have been the norm in Deinonychus palaeoart since its discovery, but is it time we changed that? Were their jaws actually visibly and powerfully muscled as inferred by their trace feeding evidence, or is there something missing here? Is it significant that lower estimates of their bite forces match those of animals which can also puncture bone (wolves - see Haynes 1982)? If anyone has anything to add, please let me know...

References

  • Fowler, D. W., Freedman, E. A., Scannella, J. B., & Kambic, R. E. (2011). The predatory ecology of Deinonychus and the origin of flapping in birds. PLoS One, 6(12), e28964.
  • Gignac, P. M., Makovicky, P. J., Erickson, G. M., & Walsh, R. P. (2010). A description of Deinonychus antirrhopus bite marks and estimates of bite force using tooth indentation simulations. Journal of Vertebrate Paleontology, 30(4), 1169-1177.
  • Haynes, G. (1982). Utilization and skeletal disturbances of North American prey carcasses. Arctic, 266-281.
  • Sakamoto, M. (2010). Jaw biomechanics and the evolution of biting performance in theropod dinosaurs. Proceedings of the Royal Society B: Biological Sciences, 277(1698), 3327-3333.
  • Therrien, F., Henderson, D. M., & Ruff, C. B. (2005). Bite me: biomechanical models of theropod mandibles and implications for feeding behavior. The carnivorous dinosaurs, 179-237.

Monday, 22 September 2014

The Spinosaurus hindlimb controversy: a detailed response from the authors

No-one with an interest in Mesozoic reptiles will have missed the week of controversy following Ibrahim et al.'s (2014) new reconstruction of Spinosaurus. The most important debate has focused on the allegedly reduced Spinosaurus hindlimbs, which are integral to the proposed locomotor and lifestyle hypotheses proposed for the 'new look' animal, but also difficult to reconcile with presented data. Scott Hartman, who's no stranger to producing high-quality skeletal reconstructions, blew this whistle first when he found the reconstructed proportions of the Spinosaurus neotype specimen - a series of vertebrae and hindlimb elements - were questionably scaled against measurements of the bones themselves. Lead author of the Spinosaurus study, Nizar Ibrahim, publicly responded and suggested that the measuring landmarks Scott used in comparing vertebral and hindlimb elements may be wrong. When reviewing the controversy before the weekend, I attempted my own scaling effort, using Nizar's suggested landmarks, but ended up replicating Scott's results almost exactly. I concluded "[s]omething - the original measurements of the specimen or the reconstruction - just doesn't add up, and I suspect the latter, as I figure someone would have owned up to and corrected simple numerical errors in the paper by now."

It turns out that I've got to eat a few of those words. Following my post, Nizar opened a chain of correspondence where I directly asked about these scaling issues. Nizar's response was bringing his coauthor Simone Maganuco into our chat, who had taken the time to demonstrate and describe how the restored vertebral and hindlimb lengths match the dimensions reported in the paper. In his screenshot and email, Simone provided an enlarged view of the restored Spinosaurus trunk and took the time to explain where he thought the alleged scaling errors came from. Appreciating their interest to a wide audience, Simone has kindly allowed me to reproduce his screengrab and email here.

Image courtesy Nizar Ibrahim and Simone Maganuco, used with permission.
Dear Mark,

It is nice to be in touch with you. I am writing to comment briefly on my photoshop image, forwarded by Nizar a couple of hours ago.

I hope it is the key to understand the misunderstanding about the measurements, so I would be really glad to know your opinion about it.

I have tried to replicate the coefficients for scaling obtained by you and Scott Hartman and here is my line of reasoning.

Look at the vertebra D8 in my photoshop image. For convenience, we can focus our attention on the D8 on the left.

The yellow line is 18 "units" (and matches our measurements in the table) but if you include the posteriormost margin of the slanted posterior face and the condyle you have nearly 23 units.

23:18=X:71 where 18 and 71 are also the measurements in cm in the table of the Science paper; 23 units is the length of the whole vertebra in the drawing; and X should be the length of the ilium to match the length of the vertebra in the drawing, if one assumes that the whole vertebra - and not the yellow line - is 18 units, i.e., if one thinks  we used different landmarks and measured the maximum length of the centrum.

The value of X is 90.72  units.

90.72 /71  = 1.27 that is exactly the coefficient for pelvic girdle and hindlimb scaling suggested by Scott @ skeletaldrawing.com to resize the pelvis and the legs to match the size of the D8 vertebra measured with different landmarks (i.e., if 18 is considered the maximum length).

I can see that your coefficient is slightly lower, and I wonder if you have taken slightly lower measurements (it seems to be the case looking at the white lines in your test).

Do you think that this could be the explanation of  what happened?

In the paper, we thought it was better to measure the vertebrae from rim to rim (the rounded margins of the faces), excluding the condyle, and at the same dorsoventral height (because some vertebrae are like parallelograms). It is easier to compare anterior dorsals and posterior dorsals in this way, and it is easier also to compare the centra with those of some specimens not prepared three-dimensionally but preserving well-articulated vertebrae, i.e. specimens in which it is difficult to look at the anterior condyle.

As what concerns the femur, it must be taken into account that there is also a slight perspective effect, because in the digital model it points a bit laterally. i.e., it is not 100% parallel to the sagittal plane.

The misunderstandings generated by the comparison between the figure and the table clearly indicate that we had to indicate our landmarks in one extra figure, or dedicate a couple of lines to this into the text to satisfy the need to compare figure and measurements by people who want to test our skeletal reconstruction.

When I work with palaeoartists to prepare illustrations and flesh-models I also compare figures and measurements, so I can understand this need.

Sometimes there are figures that are not 100% in the view indicated in the caption (also because it is not easy to put a bone in plane!) and sometimes it is difficult to understand the landmarks used to take measurements. What if I were in your shoes? Who knows... but I can understand that the new look of Spinosaurus has unexpected proportions that leads to think that there is something wrong.

In the monograph everything will be more clear because the detailed figures will report measurements directly on the bones, permitting everybody to see the landmarks.

In the meantime, however, I think it is useful to clarify this aspect.

Best wishes,

Simone

--

So there we have it: the measurements, landmarks and an image where they can be measured accurately. The latter is especially important because dorsal vertebra 8 in the full restoration is rather small, and thus prone to measuring errors even when measuring landmarks are known. A slip of a few pixels may not seem like much but, because the bone is a tiny component of a huge reconstruction, such minor errors can throw a scaling calibration right off. These risks were identified in Scott's original posts, and it seems they have been borne out. Nevertheless, it is interesting that Scott and I - and others, according to some Facebook chat - found such similar results: this could be coincidence, or it might be that the published reconstruction lends itself to a erroneous interpretation. Either way, there is plenty of food for thought here as goes presentation and reading of reconstruction data. For the record, when attempting to replicate the scaling again, this time on the screenshot, I found my results matched measured values given in Ibrahim et al. (2014) within a few percent. My confidence in the published proportions is thus fully restored.

Hopefully this helps resolve the scaling controversy with the 'Spinosaurus reboot', and the result is much more confidence about the downright weird and remarkable anatomy of this genuinely unusual animal. Thanks to Nizar and Simone for taking the time to explain their work, and allowing me to post their response here.


Reference


  • Ibrahim, N., Sereno, P. C., Dal Sasso, C., Maganuco, S., Fabbri, M., Martill, D. M., Zouhri, S. Myhrvold, N. & Iurino, D. A. (2014). Semiaquatic adaptations in a giant predatory dinosaur. Science, 1258750.

Saturday, 20 September 2014

The 'Spinosaurus reboot': sailing in stormy waters

UPDATE: 21/09/14: Following chats with Nizar Ibrahim and Simone Maganuco, it appears the Spinosaurus 2014 saga has another twist to take concerning the controversy over the revised hindlimb proportions. I'd rather write about it in a comprehensive fashion when I have the time (hopefully tomorrow) and am hoping to deliver some definitive, knock-out information from the authors which puts this controversy to bed. Bear this in mind before you read the following...

ANOTHER UPDATE: 22/09/2014: Read this.

Are depictions of Spinosaurus like this now redundant? Answer: who knows? After weeks of anticipation and teased images, the 'new look' Spinosaurus has met a sceptical reception from academics and the online palaeontology community, and they've not kept their opinions quiet.
One thing is clear a week after the 'Spinosaurus reboot' (a phrase coined by Mickey Mortimer) was revealed amidst a furore of academic and media swirl: Spinosaurus c. 2014 has not met the warmest reception from the palaeontological community. A sceptical tone, sometimes very openly so, can be seen in numerous articles from the first popular science write-ups to articles penned by professional palaeontologists. As we all know by now, the primary concerns centre around Ibrahim et al.'s (2014) new Spinosaurus aegyptiacus reconstruction, which Brian Switek describes as a 'hodgepodge [of] different dinosaurs... the new subadult skeleton, digital representations of the original and long-lost Spinosaurus bones, vertebrae and hands that may or may not belong to Spinosaurus, as well as replacement parts from an assortment of spinosaurs'. Allegations have been made that scaling errors are responsible for the unusual new bauplan rather than an unprecedented lifestyle, with the allegedly tiny legs being far more proportionate once the scaling problem is addressed. These undermine the credibility of the furthest reaching claims of the authors - theropod quadrupedality and a lifestyle/locomotory strategy akin to early whales. Two widely shared and commented blog articles on this topic over at Scott Hartman's Skeletaldrawing.com have cast enough doubt over the new reconstruction that the Spinosaurus 2014 authors publicly responded to the criticism, but the reply is really just a holding message. Other than pointing out well known problems of measuring images rather than fossils (which, to be honest, are unlikely to produce the large scaling problems levelled at the paper), the message is essentially 'all will be clear in an upcoming Spinosaurus monograph'*.

*For what it's worth, I took five minutes to measure up the new Spinosaurus skeletal restoration myself following Nizar Ibrahim's measuring instructions for dorsal vertebra 8, just to see if I could make head-or-tail of the debate. Differences in measuring landmarks were chalked up as being a potential problem, so I measured the ilium and femur blind to other methods, instead using whatever landmarks were most intuitive. For both the ilium and femur lengths, I arrived at almost identical scaling errors to Scott, and the legs should - according to the data in the paper - be c. 25-27% larger in the reconstruction. Something - the original measurements of the specimen or the reconstruction - just doesn't add up, and I suspect the latter, as I figure someone would have owned up to and corrected simple numerical errors in the paper by now. My working is below.

Independent test of the alleged hindlimb proportion issues in the new-look Spinosaurus. Skeletal reconstruction from Ibrahim et al. (2014); see Skeletaldrawing.com for the posts inspiring this test, especially this and this.
The controversy extends much further than just scaling, however. Across other articles, multiple issues have been raised including the incorporation of isolated spinosaur elements and other taxa to a single Spinosaurus reconstruction; whether all the material used in the reconstruction is of spinosaurid origin (e.g. this humerus); the likelihood for theropod quadrupedality (remember that we don't know anything concrete about Spinosaurus forelimbs: there is really nothing to suggest quadrupedality in this animal other than its alleged proportions); the authors taking too much credit for the 'semi-aquatic hypothesis'; the suitability of their journal choice and the somewhat ambiguous circumstances surrounding the provenance of the new material. And this is to say nothing of the extensive discussion on social media, much of which revolves around the same topics. This is not to say the Internet is hating on Ibrahim et al. (2014) - I think the pieces linked to here are balanced, reasoned critiques, not slanderous attacks - and, before anyone asks, I'm not saying I agree with, or even have opinions on a lot of these issues. The point here is that the 'Spinosaurus reboot' has experienced a very bumpy, almost slightly hostile landing.

The response to the Spinosaurus reboot is of some interest. Controversial, questionably-supported claims are made in palaeontology all the time, but they don't get the online palaeontology community anywhere near as riled as Spinosaurus has in the last seven days. Ibrahim et al. (2014) clearly hit a nerve, perhaps because they have inadvertently created a 'perfect storm' for scientific backlash.

At the heart of the storm is a data vacuum about Spinosaurus - an odd state to be in seeing as we're now meant to have a good idea what it looked like. The main discussion about Spinosaurus in the last week has been methodological: that is, trying to figure out how the new reconstruction has been put together. This is because the paper lacks essential details concerning how the 'hodgepodge' of spinosaur bits were scaled to size or identified as Spinosaurus aegyptiacus in the first place. In skipping these details readers are left guessing - and discussing - how the proportions were ascertained and whether they are trustworthy. That people would want to know this was predictable: you can't propose a radical notion like a famous theropod being a semi-aquatic quadruped, even converging on whale ancestors, without academics, enthusiasts and dinosaur nerds wanting to know more. While the paper does have plenty of good data, it lacks transparent methods and discussions where it counts, leading readers to make their own tests and discoveries. Lest we forget, people like talking about dinosaurs online at technical levels, and it's only natural that blogging software and social media is being fired up to discuss these revelations. It's quite likely that there'd be less fuss made if the paper stood on sounder methodological ground but, ultimately, controversy sells, in part because the continual uncovering of new information and scientific debate makes for good copy.

Compounding this effect is the star of the show: Spinosaurus itself. By now, Spinosaurus has to be one of the most popular dinosaurs of all. It's the one widely known theropod to have a size advantage over Tyrannosaurus, has starred in a couple of big movies and documentaries, is undeniably cool looking, is a bit 'alternative' as dinosaurs go... for lots of reasons, it's a major dinosaur celebrity. Even among po-faced academics, the sheer size and unusual anatomy of Spinosaurs means most - probably even guys who work on brachiopods - find it a little bit more interesting than usual. Any publication on this animal is guaranteed a good amount of casual interest, but one where the animal is almost completely reinvented will send the online palaeontology community into overdrive. Did anyone else have to wait for the Science website to stop crashing when the embargo was lifted last week? I'd be interested to see how riled the internet palaeontology community got if someone questionably reconstructed a small ornithischian. For contrast, consider that the publication of another dinosaur with a radical lifestyle - the burrowing dinosaur Oryctodromeus - ruffled relatively few feathers when it was published, despite it's PR. I remember most discussion of it on the Dinosaur Mailing List concerning the formulation of its name.

Driving the storm is the considerable hype surrounding the paper, which bears little resemblance to traditional scientific press releases and is more akin to the launch of a summer blockbuster. 'Surrounding' is the right word, too, as tantalising glimpses of the new reconstruction were online weeks before the paper's release, foreshadowing the avalanche of 'official' art, articles, and videos which would follow. There are documentaries, a tie-in exhibition in Washington DC, press conferences and lectures. You'd think Spinosaurus and its wranglers were rock stars. I mean, can you name one other palaeontological PR event which needs dry ice?

The popular side of this release has been a resounding success, which - whatever you think of science being spun as a media event of this kind - is certainly well earned. In concert with National Geographic, Ibrahim et al. (2014) have put on a very slick, professional show with some wonderful art and graphics, and they've certainly made it difficult to miss. But publicity can be polarising, not to mention difficult to steer. It seems the PR for Spinosaurus 2014 has somewhat backfired in the palaeoblogosphere, the conspicuous, sensational nature of the story encouraging interested minds to investigate and test, and ultimately question the findings at the core of the hype. I expect the extensive publicity surrounding a widely-questioned paper also brings a faint sense of irritation to some, prompting them to advertise the fact that the conclusions are not as watertight as the documentaries, exhibition and magazine covers indicate. Whereas other studies with problematic conclusions would slip away into the literature to be discussed within the closed confines of scientific journals, Spinosaurus 2014 cannot hide easily: the advertising and publicity for this paper is keeping the controversy relevant and prompting more responses. I do wonder what National Geographic, presumably footing the bill for all this press work, are making of the frosty scientific response to Spinosaurus 2014.

Between the data vacuum of a radical new proposal, a megastar fossil animal and persistent reminders of a controversial study, it's hardly surprising that the online palaeo community has spent the week giving the Spinosaurus reboot a good grilling. What does the future hold? With the promise of a Spinosaurus monograph, we can be sure that there will be more discussion eventually, but, more realistically, the next major ripples will follow response papers. Some authors are already in talks about this and - given what's been demonstrated online already - there are strong cases to be made against the main hypothesis of the Spinosaurus reboot. Is a rebuttal article appropriate with another paper on the way? Yes, entirely, because we have to work with data which is available and test the hypotheses presented to us. In this case, the new-look Spinosaurus and the many implications made about its habits have been quickly questioned - deemed irreproducible, even - by a number of scientists, and this should be 'formalised' as a genuine concern about the initial paper. The upshot, of course, is that the eventual monograph will have to take this into account, which should make for a stronger publication, and hopefully an improved understanding of Spinosaurus itself.

I can't help think that there are a few causalities from the last week, not least being the good new data in Ibrahim et al. (2014), such as Spinosaurus weirdly tetradactyl feet, unusually short femur and dense bones (Ibrahim et al. 2014). What do these mean, in light of the hindlimb scaling controversy? Is the long first toe more to do with spreading weight than creating a flipper? Are the thickened bone walls more to do with relocating the centre of gravity than swimming? There are interesting discussions to be had there, but they've been overshadowed by other details. Also, scaling issues or not, I imagine the 'dachshund' Spinosaurus is here to stay for a while, so we can look forward to having to downplay confidence about the new reconstruction of Spinosaurus for the foreseeable future. It's very doubtful that the press will be interested in a story about the uncertainty over a new paper, nor is National Geographic likely to replace the legs on its Spinosaurus model with question marks. This is a constant bugbear of working within science of course: the media is interested in new and exciting discoveries, but has virtually zero attention span for scientific debate.

Finally, is there anything to learn from this? For me, the message is that while publicity is largely about presenting conclusions and results, we can't just assume our audiences are passive. Particularly if you're discussing a fan-favourite species (and let's face it, 'fans' here includes a good number of vertebrate palaeontologists), people remain just as interested in what you've done as what you conclude, and omitting those details leaves papers, and those associated with them, vulnerable to misunderstandings and criticism. As demonstrated this week, even the combined might of Spinosaurus and its PR campaign is not immune to this: when the world's largest theropod took a bite out of the Internet, it was bitten right back.

Reference


  • Ibrahim, N., Sereno, P. C., Dal Sasso, C., Maganuco, S., Fabbri, M., Martill, D. M., Zouhri, S. Myhrvold, N. & Iurino, D. A. (2014). Semiaquatic adaptations in a giant predatory dinosaur. Science, 1258750.

Tuesday, 9 September 2014

The new African titanosaur which (almost) got away: Rukwatitan bisepultus

Rukwatitan bisepultus, a new titanosaurian sauropod from the Middle Cretaceous (Aptian/Cenomanian) of Tanzania. Why does this otherwise chirpy scene feature a dying Rukwatitan? Read on...
Hot on the heels of super titanosaur Dreadnoughtus comes another new Gondwanan titanosaur, Rukwatitan bisepultus Gorscak et al. 2014 (press release restoration, above). As indicated by the publication of two new sauropods in close succession, we live in a time where our knowledge of sauropods dinosaurs is expanding rapidly. This surge in interest and activity is perhaps less conspicuous than other expanding areas of palaeontology - sauropods don't grab the headlines as much as small, feathered theropods - but it's fair to say that the landscape of sauropodomorph research has changed considerably in the last two decades. This particularly applies to our appreciation of their diversity and distribution across space and time. Once, the sauropod story could came to a near-end in the upper Jurassic once diplodocids started to decline, but we now know that titanosauriforms kept the sauropod end up throughout the Cretaceous, being abundant, widely distributed and diverse until the end of the Mesozoic. They appear particularly important in South America, where something like 39 species have been recovered (Gorscak et al. 2014).

Schematic of known elements of Rukwatitan bisepultus. From Gorscak et al. 2014.
Rukwatitan bisepultus is not South American however, but African, specifically from the 'middle' Cretaceous (Albain-Cenomanian) Galula Formation of Tanzania. Africa's Mesozoic faunas remain poorly known and, as one of only four named sauropods from 'middle' Cretaceous Africa, as well as a component of relatively poorly-known sub-Saharan Cretaceous forms, Rukwatitan is a find. Thus far, Rukwatitan is the only named sauropod from the Galula Formation, but other Galula fossils record a 'typical' Gondwana fauna of gondwanatherian mammals, notosuchian crocodyliforms (including the carnivoran-immitating Pakasuchus, below) and osteoglossomorph fish, as well as indeterminate small theropods and turtles (Roberts et al. 2010). Rukwatitan can be seen as another component of a middle Cretaceous sub-Saharan sauropod assemblage, joining the roughly contemporaneous sauropods, Malawisaurus dixeyi and Karongasaurus gittelmani of Malawi, along with scrappy fossils which hint at additional species. Represented by an incomplete skeleton (above) and a referred humerus, Rukwatitan is a relatively small titanosaur, although its exact size is difficult to gauge. It is seemingly larger than the relatively completely known (and probably closely related, see below) Malawisaurus, Rukwatitan humeri being 20 and 28% larger than those of Malawisaurus. With Malawisaurus estimated at about 9 m long (not 16 m as indicated in Paul 2010! - see comments below), this puts Rukwatitan in a rough length ballpark of 10-12 m.

Rukwatitan is not my first artistic trip to ancient Galula: in 2010 I helped Patrick O'Connor et al. restore their unusual notosuchian crocodyliform, Pakasuchus kapilimai, famous for it's cat-like slicing dentition. The word on the palaeo grapevine is that there's a lot more to come in the world of African crocodyliforms. I'd like to have another crack at rendering these guys, so I'll be waiting by the phone if anyone wants me...
Titanosauria is an increasingly big group, so leaving Rukwatitan with this label doesn't tell us much about its relationships to other sauropods. A useful phylogenetic landmark within Titanosauria is Lithostrotia, the group of derived titanosaurs which includes many famous taxa: Saltasaurus, Opisthocoelicaudia, Alamosaurus, Nemegtosaurus and Malawisaurus. This clade also contains all known armoured titanosaurs, although armour is not ubiquitous across the group (D'Emic et al. 2009). Other titanosaurs form successive offshoots from the titanosaur evolutionary line leading to Lithostrotia, and it's among these that Gorscak et al. (2014) place Rukwatitan. It only just misses inclusion within Lithostrotia however, suggesting close evolutionary ties to basal members of this group, including the geographically and stratigraphically proximal Malawisaurus. This mirrors findings that some geographically proximal, middle Cretaceous sub-Saharan reptiles - most notably Crocodyliformes - are also closely related, and substantiates ideas that sub-Saharan faunas were evolving at a relatively local, as opposed to cosmopolitan, or even continental-scale level (O'Conner et al. 2006; Gorscak et al. 2014). Possible further evidence of sub-Saharan regions being biogeographically distinct in the mid-Cretaceous stems from an apparent absence of many north African dinosaur groups. Although titanosaurs occur across the continent, evidence of large theropods (spinosaurids and carcharodontosaurids), other sauropod groups (rebacchisaurids, non-titanosaurian titanosauriforms) and ornithopods is currently lacking in Albian-Cenomanian deposits south of the Sahara. Will these animals turn up in time? Perhaps, but the continental Cretaceous beds of Tanzania and Malawi are not new localities only now being exploited, but the sites of many years, even decades of fieldwork. If north African dinosaur groups were there, their fossils are remaining well hidden.

Giving Rukwatitan a tighter address within Titanosauria helps us flesh out a rough projection of its bauplan with a little phylogenetic bracketing. The neck was probably relatively long compared to the tail, evidenced by phylogenetic neighbours and proportions of the preserved vertebrae (note that the schematic above is probably a little wimpy on the neck end of things). It's limbs were likely robust and relatively equally sized, and it's skin probably lacked osteoderms. A short, deep skull seems likely because Rukwatitan is bracketed by short-faced Titanosauriformes, but note that the bracket here is quite loose thanks to the deficit of sauropod skull material. We leant heavily on the well-known anatomy of Malawisaurus for our reconstruction (Gomani 2005), including Scott Hartman's skeletal.

style="font-style: italic;">Rukwatitan: river victim

Quarry map of the Rukwatitan holotype specimen, looking at the cross-section of the quarry stratigraphy rather than a 'birds eye view' of a specimen spread over a single horizon. Note the distribution of the skeleton over two layers, the mudstones (representing overbank deposits - the riverbank) and sandstones (fluvial deposits - the river channel). From Gorscak et al. 2014.
The Rukwatitan type specimen has a story to tell beyond representing a new species and carving up African dinosaur biogeography: it has an unusual taphonomic history. The taphonomic agents removing bones from ancient carcasses destined to fossilise are largely anonymous: scavenging, decay and physical processes all have their part to play, but which processes affect specific specimens is often anyone's guess. This is not so with the Rukwatitan holotype: taphonomy, foul destroyer of data and frustrater of palaeontologists everywhere, has been caught with it's pants down.

Unusually for a fossil of any kind, the Rukwatitan holotype is spread over two sedimentary horizons: a layer of fine clays and muds, which represent an ancient overbank deposit (the fine sediments laid down by floodwaters in the area alongside a river), and an irregularly bedded sandstone horizon (an erosive river channel deposited over the hardened muds). We can interpret this story as beginning with a Rukwatitan carcass lying alongside a river, having finally come to rest on it's left side, indicated by the left elements of the skeleton being preserved lowest in the sequence. Clearly, the left side of the animal was buried first. The semi-articulated nature of the remains indicate that the carcass was in reasonable shape while this was happening: there was probably still soft-tissues holding it together. How completely it was buried is not clear, but it was left long enough for those soft-tissues to at least rot and weaken, if not disappear entirely. We know this because the carcass was not left buried indefinitely: a river channel scoured through the muds burying the Rukwatitan and began removing pieces of the carcass either wholesale, or by breaking the bones to pieces. The Galula Formation is essentially a large river braidplain where large (hundred of metres wide, and c. 10 m deep), relatively straight rivers would frequently change course to rework their environment (Roberts et al. 2010). Even though preserved soils and root-systems indicate that the riverbanks were bound together by plants (presumably doing well in the sub-tropical climate - Roberts et al. 2010), it seems that they were no match for these large, ephemeral rivers, and the remains of ancient bank collapses were visible alongside the in situ Rukwatitan remains. Now exposed to a torrent of water, the carcass lost many smaller bones (these are absent in the holotype) and larger bones were being disassembled. If left unabated, this Rukwatitan would have probably been eroded completely, but the river channel was particularly short lived and rapidly filled with sand. Indeed, the high energy phase of the channel incision didn't last too long at all, as many larger bones were only transported metres downstream, and their broken margins still fit the elements left in the mudstones, indicating limited exposure on the newly formed riverbed. This left us with a good chunk of titanosaur to find, but Gorscak et al. (2014) think another 'river attack' - this time the River Namba - scoured more material away in recent years. The Rukwatitan species name, bisepultus, means 'twice buried', a reference to the holotype being a veteran of erosive and re-burial processes.

If you're moved by the story of Rukwatitan specimen RRBP 07409 and want to know how you can help dinosaurs who've suffered river attacks, please contact me for details of charities and fundraising events.

We wanted to include a nod to this taphonomic story in our press artwork, which is why there's a dying or recently dead Rukwatitan at the base of the image. The cause of death for the Rukwatitan holotype is unknown, but we wanted to include some live sauropods, so it seemed sensible to attribute the death to 'natural causes' rather than an environmental catastrophe or predatory species. For fun, I included a few lesions around the mouth of the dying individual as hints of a trichomonosis-like infection, the same protozoan known to infect birds and other theropod dinosaurs to erode their bones and inflame their upper digestive tracts, leading to death from starvation (Wolff et al. 2009). Would sauropods be vulnerable to this infection? Possibly: trichomonosis leaves lesions in the lower jaw of it's victims which, to a pathologist, are quite characteristic. These lesions haven't been found in any sauropods to my knowledge, but similar ones have been found in other ornithodirans - pterosaurs (Wolff, pers. comm. in Witton 2013) - suggesting many members of this group were vulnerable to this protozoan. It's speculative, sure, but I figured it was a fun nod to other recent dinosaur research.

And finally, a request

We're just about done here, but one last point to make. Between this post, the last, and featuring more new sauropod art over at Palaeontology Online, I've developed a real hankering for a good sauropod book. You know, a readable, fully referenced overview of their history of study, anatomy, palaeoecology, biomechanics, evolutionary history and diversity (so, nothing major then). I'm quite serious here: they're an awesome, popular group of animals, fully deserved of their own semi-technical overview, ideally with lots of images to showcase their anatomy and habits. I'm sure this idea has sufficient legs to interest a major publisher. I lack the expertise to write it, so this is my attempt to plant a seed in the minds of those who can. For what's it's worth, I'd gladly help illustrate it: sauropods are fantastic fun to draw, and it'd be terrific to bring the diversity of this group to life in artwork.

I leave you with this image, which was drafted in response to Eric Gorscak's comments about the Rukwatitan press image: "Other than the lack of laser beams, I think it is looking fantastic!" Not wanting to disappoint, I duly complied...

Oh no, what caption to use? 'Pods of War? 'Podageddon? DinosAWESOME? Too... many... puns...

References

  • D'Emic, M. D., Wilson, J. A., & Chatterjee, S. (2009). The titanosaur (Dinosauria: Sauropoda) osteoderm record: review and first definitive specimen from India. Journal of Vertebrate Paleontology, 29(1), 165-177.
  • Gomani, E. M. (2005). Sauropod Dinosaurs from the Early Cretaceous of Malawi, Africa, Palaeontologia Electronica Vol. 8, Issue 1, 27A: 37p.
  • Gorscak, E., O'Connor, P. M., Stevens, N. J. & Roberts, E. M. (2014). The basal titanosaurian Rukwatitan bisepultus (Dinosauria, Sauropoda) from the middle Cretaceous Galula Formation, Rukwa Rift Basin, southwestern Tanzania. Journal of Vertebrate Paleontology. In press.
  • Paul, G. S. (2010). The Princeton Field Guide to Dinosaurs. Princeton University Press.
  • O’Connor, P. M., Gottfried, M. D., Stevens, N. J., Roberts, E. M., Ngasala, S., Kapilima, S., & Chami, R. (2006). A new vertebrate fauna from the Cretaceous Red Sandstone Group, Rukwa Rift Basin, southwestern Tanzania. Journal of African Earth Sciences, 44(3), 277-288.
  • O’Connor, P. M., Sertich, J. J., Stevens, N. J., Roberts, E. M., Gottfried, M. D., Hieronymus, T. L., Jinnah, Z. A., Ridgely, R., Ngasala, S. E. & Temba, J. (2010). The evolution of mammal-like crocodyliforms in the Cretaceous Period of Gondwana. Nature, 466(7307), 748-751.
  • Roberts, E. M., O’Connor, P. M., Stevens, N. J., Gottfried, M. D., Jinnah, Z. A., Ngasala, S., Choh, A. M. & Armstrong, R. A. (2010). Sedimentology and depositional environments of the Red Sandstone Group, Rukwa Rift Basin, southwestern Tanzania: New insight into Cretaceous and Paleogene terrestrial ecosystems and tectonics in sub-equatorial Africa. Journal of African Earth Sciences, 57(3), 179-212.
  • Witton, M. P. (2013). Pterosaurs: natural history, evolution, anatomy. Princeton University Press.
  • Wolff, E. D., Salisbury, S. W., Horner, J. R., & Varricchio, D. J. (2009). Common avian infection plagued the tyrant dinosaurs. PloS one, 4(9), e7288.

Saturday, 6 September 2014

Hey Dreadnoughtus, not so close

I try to avoid hopping on the bandwagons following new discoveries - few internet experiences are more tiresome than seeing social media and inboxes swollen with discussions and pictures of the same new fossil species (tyrannosaurids, for some reason, do this more than anything else). Of course, some new discoveries are just too cool to pass up: Dreadnoughtus schrani Lacovara et al., 2014 is one of them. Not only does it have a fantastically marketable and charismatic name entirely befitting one of the largest land animals to ever exist (take that, naysayers), but the sheer amount of data published on it is really first class (Lacovara et al. 2014) and the fossil is truly spectacular. If you've not done so, check out the Dreadnoughtus description and supplementary material: there's everything from measurements and photographs to interactive 3D scans of every bone for you to look at in fine detail (or spin around like crazy while giggling, if you're comfortable enough with your maturity). And before you can say 'paywall', this is all freely-available, open access information. It's not just a great paper for those interested in sauropods or dinosaurs, but also an important reference point for those interested in the evolution of extreme animal anatomies and gigantism.

How the world met Dreadnoughtus schrani in palaeoart. Left, restoration by Jennifer Hall; right, Mark A. Klingler. Images from the Dreadnoughtus media release hosted at the Drexel News Blog.
I found one aspect of the very good, super-comprehensive and fittingly giant media release for Dreadnoughtus rather unusual, however: the artwork. For a media story principally being sold on the size of a dinosaur, the two 'official' pieces of Dreadnoughtus artwork by Mark A. Klingler and Jennifer Hall (above) have - what seem to me at least - some odd choices as goes composition and posture which might undermine the awesome size of Dreadnoughtus. I'm not saying the images are bad or 'wrong': there's lots of lovely detail and atmosphere in both (note the neat sauropod and titanosaur characteristics like the lack of manual claws, the concave posterior surface of the hand etc.), and this is not a dig at the artists, who have definitely earned the wide success of the Dreadnoughtus press campaign. My problem - and I hope this comes across as the constructive criticism it's intended as - is that I'm a bit underwhelmed by the sense of scale, which I'd say is pretty important for artwork of this animal. To be fair, conveying extinct animal size in art is never straightforward, but peculiar compositional choices in each image prohibit my being fooled into thinking I'm looking at truly giant animals. For example, both position the animals in the foreground, filling the canvas with as much Dreadnoughtus hide as possible. I can understand why - it says "it's so big we can barely contain it in the edges of these illustrations", but it also leaves little room for a point of size reference between us and the animals. It also forces the adoption of stooping postures and requires significant foreshortening to fit the animals into view, the former reducing their apparent size and the latter obscuring proportions we intuitively recognise as characteristic of large animals (e.g. the relatively small heads of large animals). Hall's illustration also sets the point of view at shoulder height so we're actually looking across and somewhat down at the subject animal - not necessarily what you might want to suggest this thing was bigger and taller than us. Both images feature trees immediately alongside their animals as a means of conveying scale, but I find the rest of the composition overpowers their effect. In all, while the other aspects of the images are effective, I'm just not sold on the size.

I find these decisions interesting because I think they represent a case of a modern palaeoart convention overruling 'classical' artistic approaches. Traditionally, artists use the same basic techniques for making subjects look big and important when placing them in a scene. They stress proportional extremes (including small head size - this even occurs in renditions of royal or divine human figures), use low points of view so that the the top of the subject clears the horizon line along with other elements in the composition, and place items to give an appropriate sense of scale. Positioning smaller items in the foreground can help the viewer find their position in the scene and ground their sense of size, but these need to be placed carefully: cluttered compositions tend to dwarf their subjects. A consequence of these methods is that giant subjects are often no closer than the mid-ground. An obvious exception to this are images with points of view positioned at the very base of a subject, looking up, so it looms above the viewer (below). This is a slightly different approach to the problem, though, almost treating the subject as the landscape rather than an entity within a background.

A cockroach-eye view of a titanosaur.
Palaeoart produced before the 1970s/1980s stuck to the classic rules of depicting giant animals: Zallinger, Knight, Burian et al. rarely deviated from 'standard' methods of conveying large size when drawing sauropods and other big extinct animals. The scientific transformation of dinosaurs into dynamic, active animals in the late 20th century also brought on a artistic shift where some artists abandoned 'classic' compositions in favour of more exciting, convention-defying and 'extreme' images. One consequence of this was some artists moving (frequently giant) animals closer to the foreground, turning them to face viewers and sometimes, through their body language, 'interacting' with those looking at them. The first seeds of this were probably sown by by the likes of Robert Bakker who, in many of his illustrations, fills every possible square inch with his animals to the point of using extreme postures - particularly arching backs and curving tails - to do so (e.g. illustrations in Bakker 1986). Bakker's works frequently lack the context of backgrounds however, leaving other artists to bring dynamically posed, big extinct animals closer and closer in landscaped works. I think Mark Hallett may have be particularly instrumental here, with works such as his famous 1984 'Dawn of a New Day', and the 1985 paintings 'Awakening of Hunger' and 'Ancient One' leaning towards, or perhaps even pioneering, an 'in your face' style of palaeoart where the subjects are looking at, sometimes menacing, their viewers (if anyone did this earlier, please let me know). Such artworks would become common in the 1990s, with Luis Rey famously combining these compositions with extremes of colour, perspective and pose to produce a style which has since been widely imitated. It's from such imagery that 'slasher' palaeoart arose, those images were animals are rushing, teeth and claws bared, at the viewer from within the painting.

Attitudes towards these foreground-emphasised, perspective heavy images are often divisive among palaeoart aficionados - some love them, others hate them. Fans of such works point out their utility for outreach, in that they're relatively novel, different, fun and striking, while detractors note their distortion of proportion, not to mention that many look, well, silly (I've argued elsewhere that this may have negatively skewed public perception of feathered dinosaurs). The most relevant common complaint to our discussion is that they lose all sense of scale, essentially for all the reasons listed above: unfamiliar proportions, a lack of foreground space to place 'scaling' elements, and often the loss of height associated with moving the anatomy into a position where it can all be seen behind the head (for many infamous examples, see Brusatte and Benton's enormous book Dinosaurs (2008)). Whatever your opinion, we can't deny their success and influence. such images are now a standard palaeoart convention, particularly in children's books, and have been used to showcase virtually any prehistoric animal you can think of. In this respect, the arching, frame-filling Dreadnoughtus images released last week are just following this now familiar palaeoart convention.

Thing is, I'm not sure if this practise works for all palaeoart, and especially in images where conveying size and anatomical details are important. Of course, the ultimate success of a composition is a matter of taste, and there is no actual 'right' or 'wrong' to palaeoart so long as it obeys basic laws of anatomy. But here's the beef: palaeoartworks often have a purpose - very commonly to convey the anatomy and size of a new species - but 'full frame' animal compositions are probably the worst composition to demonstrate these attributes, for reasons discussed above. Moreover, and fundamentally related to the goal of palaeoart being realistic portraiture of extinct species - how do we rationalise the adoption of the contorted postures required to fit the animals into frame? Why would these animals be condensing themselves into such weird shapes? And what do these poses look like from other angles? Wouldn't they look, at best, a bit odd? For me, seeing a restored animal in an unconventional, maybe even biomechanically implausible pose so it can take up more of the canvas is jarring, a reminder than I'm looking at an reconstructed animal rather than one an artist saw with their own eyes.


For art where proportions and a sense of scale is important, pushing our subjects back to the tried and tested middle distance would alleviate these problems, without jeopardising their excitement. Palaeoart was just as inspirational and exciting to audiences before we started rendering animals right under our viewer's noses, after all. Ultimately, while there's nothing inherently 'wrong' with any composition in palaeoart, some compositions suit certain scenes and animals more than others, and some are definitely more informative and educational than others. 'Full frame' compositions certainly have their place within palaeoart, but they're probably more limiting artistically and educationally than the alternatives.

I'll leave you with my own take on Dreadnoughtus, a quick painting done as the end result of my spate of fanboyism on Thursday night. And if you like sauropods, stay tuned, because there's more on the way...

The mighty Late Cretaceous titanosaur Dreadnoughtus schrani, making a mockery of two abelisaurids just by existing. Abelisaurids aren't known from the same formation as Dreadnoughtus, but are the most likely theropods to have occurred there given their abundance in the other Late Cretaceous South America. These are loosely based on Aucasaurus.

Update: 07/09/2014, well past bedtime

Not many moments after posting this, arty chum Jon Davies (@SovanJedi) responded with an image on Twitter which sums up the few thousand words above into one image:

It's funny because it's true.

References

  • Bakker, R. T. (1986). The Dinosaur Heresies. London, Penguin.
  • Brusatte, S. and Benton, M. J. (2008). Dinosaurs. Quercus.
  • Lacovara, K. J., Lamanna, M. C, Ibiricu, L. M., Poole, J. C., Schroeter, E. R., Ullmann, P. V., Voegele, K. K., Boles, Z. M., Carter, A. M., Fowler, E. K., Egerton, V. M., Moyer, A. E., Coughenour, C. L., Schein, J. P., Harris, J. D., Martínez, R. D., and Novas, F. E. (2014). A gigantic, exceptionally complete titanosaurian sauropod dinosaur from Southern Patagonia, Argentina. Scientific Reports. 4, 6196; DOI:10.1038/srep06196.