Friday, 5 December 2014

Overcooking Aucasaurus garridoi

Aucasaurus made a note in its diary after this. Simply said: "Bugger". Prints are available.
This week I've been mostly rendering an abelisaurid, the theropod group best known for short-faced, short-armed taxa such as Carnotaurus, and famous for occupying many predatory niches in southern continents while tryannosaurids occupied the north. This 'common knowledge' is only mostly true however: abelisaurids did spread to at least Europe in the uppermost Cretaceous, and represent the largest predatory dinosaurs on the continent at that time. We need not overstate that significance however: uppermost Cretaceous Europe was a topsy-turvy world where all theropods were rather small, and top-dog predator duties were likely filled by terrestrially-stalking, quarter-tonne azhdarchid pterosaurs. It seems even evolution likes a good Htichcockian-twist every now and then.

In southern continents, abelisaurids remained medium-to-large sized predators. It was one of these, the Campanian, Patagonian species Aucasaurus garridoi that Felix Bridel asked me to paint as one of my £100 palaeoart commissions. Aucasaurus is one of the best known abelsisaurids, the holotype skeleton presenting an almost complete osteology of this c. 5 m long animal, and is considered a 'derived' member of the abelisaur clan. Its anatomy is almost as unusual as that of its close relative Carnotaurus. Like other abelisaurids, the general bauplan of Aucasaurus was that of a small head, tiny arms and relatively gracile torso strapped to a robust, probably powerfully muscled hindlimbs and tail. The peculiar anatomy of derived abelisaurid proximal tail vertebrae created huge spaces for hindlimb muscle-anchorage and likely betrays tremendous sprinting power (Persons and Currie 2011). Perhaps this explains the strange upper-body anatomy of abelisaurids: their gracile bodies and reduced extremities may represent pressures to keep weight down and speeds high. Long term readers may reconcile some components of this functional complex with another group of dinosaurs, the ornithischian clade Dryosauridae, which also married a powerful set of legs with a svelte upper body.

Felix wanted to incorporate the notion that Aucasaurus and similar species were probably fast runners into his commission, but not in a conventional way. While recent research has hinted that abelisaurids were likely fast, they were likely not as agile as other taxa. Bulging abelisaurid hindlimb muscles may have created a lot of power, but they also kept the tail base rather immobile (Persons and Currie 2011). In tight turns, the tail probably fairly ineffective for adjusting gravity centres or resisting turning inertia. Felix wanted his Aucasaurus image to reflect this, showing a predator which had overcooked its pursuit of a more nimble prey item and lost balance altogether. I was more than happy to oblige: watching animals for any length of time reveals they are just as clumsy as we are, but we seldom see palaeoart reflecting this. Perhaps the only exception is predators being thwacked by the weapons of their prey, which I guess sort of reflects a clumsiness, but it's not quite the same level of slapstick as an animal slipping over.

My brief working time with Felix was a lot of fun: it was clear from our first few emails that we had a similar idea in mind and the image came together quickly. I posted my progress of the image up on Twitter and, as you can see below, the basics of the image weren't altered from the start. Efforts were made to show the Aucasaurus mid-slip: deep enough into the fall for some immediate reaction to show, but early enough that the limbs and dust still have to settle. To my mind, the animal's right leg flew out from beneath it when attempting a tight left-turn, leaving it to gaze off-canvas at whatever prey item it was pursuing.


That final Tweet did indeed feature the finished version (also seen at top), which is now being printed and packaged for delivery (click here if you would like your own copy). As usual, there's a lot more to say, but I'll have to end there. Before I go, a few nods are needed as goes sources for the picture: Scott Hartman's Aucasaurus skeletal was an important reference, as was the Coria et al. (2002) description of the Aucasaurus holotype. The notion that abelisaurid arms were used as display structures (termed 'pom pom arms' by @Blackmudpuppy) isn't new: All Yesterdays (Conway et al. 2012) explored that first.

References


  • Conway, J., Kosemen, C. M., & Naish, D. (2012). All Yesterdays: Unique and Speculative Views of Dinosaurs and Other Prehistoric Animals. Irregular Books.
  • Coria, R. A., Chiappe, L. M., & Dingus, L. (2002). A new close relative of Carnotaurus sastrei Bonaparte 1985 (Theropoda: Abelisauridae) from the Late Cretaceous of Patagonia. Journal of Vertebrate Paleontology, 22(2), 460-465.
  • Persons IV, W. S., & Currie, P. J. (2011). Dinosaur speed demon: the caudal musculature of Carnotaurus sastrei and implications for the evolution of South American abelisaurids. PloS one, 6(10), e25763.

Friday, 28 November 2014

You won't believe how interesting the Mesozoic mammaliaform Morganucodon watsoni actually is!

Morganucodon watsoni forage for insects and spiders at night among Carboniferous limestones in early Mesozoic Wales. Empty, torn webs suggest they're having a good night, while forest fires burn in the background. Prints are available.
Vertebrate palaeontology textbooks always devote a good chunk of space to morganucodonts, a clade of Triassic-Jurassic Mammaliaformes representing some of the first wholly 'mammal-like' synapsids. Even folks largely uninterested in Mesozoic synapsids will be familiar with two morganucodonts - the Triassic, South African Megazostrodon and the widely-spread Triassic-Jurassic Laurasian genus Morganucodon - because they have become the quintessential 'Mesozoic mammal': small, shrew-like creatures which scurried around the feet of reptiles. Their lack of unusual proportions or adaptations for specialist lifestyles has probably played a part in Mesozoic mammaliaforms being considered a bit boring compared to their dinosaur contemporaries (sorry, mammal palaeontologists), a feat not helped by a deficit of new, particularly interesting artwork of them. Morganucodont representations in palaeoart are frequently quite 'diagrammatic' with 'generic' early Mesozoic backgrounds, animals in lateral or anterolateral aspect to show off their anatomy and daylight settings, despite frequent discussion about their possible/likely nocturnal habits.

Recently, I was asked to produce a reconstruction of Morganucodon watsoni for some friends (above). Being better versed in reptiles than mammals, I had to undertake a fair bit of research to bring myself up to speed on morganucodont anatomy and evolution. Turns out that reputation for being dull is entirely unwarranted: Morganucodon, its relatives, and the world they inhabited are really fascinating. Indeed, they should be bona fide fossil celebrities: Morganucodon and Megazostrodon were the first Mesozoic mammaliaforms known from anything like complete remains (albeit lots of fragments for the former, rather than a single complete specimen) instead of mere teeth and jaws. Their discovery in the mid-20th century can be seen as the start of a new era of understanding of Mesozoic mammaliaform life, and a forerunner of our now rapidly expanding knowledge of Mesozoic mammal diversity.

Initially, I wanted to write a long, detailed post about this painting and the animals it depicts, but that just won't be happening this side of 2015. But, dammit, Morganucodon is too cool to ignore completely or short-change with a 'picture of the day' post, so here's a quick-fire, from-the-hip summary of the research behind the work.

We'll start with the setting. Fossils of M. watsoni occur in British Triassic/lower Jurassic 'fissure fills' cropping out around Bristol and south Wales. These deposits represent ancient infills of caves carved into much older Carboniferous limestones, which are perhaps best known for yielding the sauropodomorph Thecodontosaurus. Fissure fill outcrops occur in multiple quarries across the southern UK and are frequently rich in fossil material, but the mammaliaforms are rare components of the fauna constrained to just a few localities. Dating the fissure fills is not easy because they contain few fossils useful for dating. Some quarries are reliably set at the Rhaetian, but they are probably not all of the same age: some may be as young as the earliest Jurassic. These include sites which contain M. watsoni fossils, which is why different texts give slightly different ages for this animal.

The upper Triassic/lower Jurassic of Europe would be an ideal holiday location for many. The desert landmass of Pangaea was in the process of breaking up, and Europe - including the southern UK - was in the process of being flooded by shallow seas. By the time M. watsoni appeared, Britain's only landmasses were small, low-lying, forested islands which, in terms of climate and general topography, would have resembled those of the Caribbean. Burned plant remains in the fissure fills indicate that the forested inlands of these islands burned on occasion, the remnants of forest fires being washed into coastal limestone caves by storms and floods. We can identify the fissure fill caves as coastal because they contain marine fossils along with terrestrial and freshwater species. It's on these limestones that I set this painting, a deliberate move to avoid another cycad-filled 'semi-arid' Triassic scene.

The island home of M. watsoni was ruled by reptiles - but not necessarily the ones you expect. Although dinosaurs were common, represented by both sauropodomorphs and theropods, the most abundant and diverse reptile group were sphenodonts. These guys deserve their own posts and paintings one day, their Mesozoic run being far more than just spreading tuatara clones across the world. Anyway, the decaying body of one of these - Planocephalosaurus - can be seen in the foreground of the painting above. As these indicate, the sphenodonts contemporary with M. watsoni weren't huge, but they still likely gave the resident mammaliaforms a hard time in competing for similar food resources. It's interesting to ponder how these animals carved up their respective ecologies to avoid direct competition with one another.

Scientists predict that, if Morganucodon were alive today, the sight of them would make grown women leap on their chairs, clutching the skirt tails in fear. 
What of Morganucodon itself? The skeleton of M. watsoni is small (about 10 cm nose to tail base) and extremely mammal-like, with differences limited to fine anatomical details. For instance, the composition of the Moranucodon jaw-joint isn't a simple as those of true mammals, the scapula is a little bit 'reptile-like', and (according to some sources, anyway), there may have been some degree of bowing to the fore- and hindlimbs when walking or standing. This doesn't necessarily indicate sprawling limbs, but they may not have been as neatly tucked under the body as those of other mammals. Because morganucodont skeletons are so similar to those of true mammals, it seems likely that many aspects of our basic soft-tissue anatomy were established by this point of synapsid evolution - ear pinnae, fur, loose skin and so on. Direct evidence for these are currently lacking in morganucodonts, but there is indirect evidence for fur from the relatively large Morganucodon brain. Although not as large as those of later mammals, Morganucodon endocasts were expanded beyond a typical 'reptilian' condition, and much of this reflects an enlarged neocortex. This part of the brain processes sensory information, and it may be that the covering mammaliaform bodies with pressure-sensitive hairs promoted this development. I find this observation quite interesting because other lineages with fuzzy bodies - bird-like dinosaurs and pterosaurs - have also developed expanded brains and enhanced abilities to process sensory information. These enlargements are often attributed to enhanced balance and coordination, but might they also be related to the developed of sensitive fuzzy hides, as is assumed for mammals?

Because art of Mesozoic mammals scurrying about at night is so rare, I wanted to capture this in my painting. The evidence for nocturnal activity in Mesozoic mammaliaforms is not as strong as you might think - it's largely based on the (questionable?) assumption that reptiles forced early mammals into nocturnal niches and the abundance of small nocturnal mammals in the modern day - but what the heck: it makes for a fun picture. It seems nocturnal mammals are often equipped with tremendous sets of whiskers, so I put similar features on my Morganucodon to help them find their way around, They may not be 'true' whiskers, in the sense of derived, mobile whiskers of modern mammals, but it doesn't seem unreasonable to imagine long, stiffened sensory hairs of some kind developing rapidly once fur was attained.

And... blast it, I'm out of time. So many other things to say, but they'll have to wait for another time. Coming soon: various theropods, festive pterosaurs, er... and probably other things too!

Friday, 14 November 2014

Of tiny tyrants and Triassic big-heads: Tyrannosaurus rex and Garjainia madiba

This week sees two new pictures of mine being 'released' in one way or another. Much as I'd like to go into lots of detail about each, that realistically isn't going to happen anytime soon. I'm going to attempt a sort of 'picture[s] of the day'-style writing. I'm sure I can do it... right?

Chidumebi Browne's resting Tyrannosaurus teens

Two young adult old male (left) and female Tyrannosaurus on a break from pillaging and destroying the Cretaceous, distracted by a group of ruffian moths. Concept and animal colouration by Chidumebi Browne. Prints are available.
First up is one of my '£100 palaeoart offers', painted for Chidumebi Browne. Featuring Tyrannosaurus, which needs no introduction as an dinosaur most famous for antisocial tendencies, Chidumebi wanted a more relaxed approach to tyrant dinosaur art. The concept called for Tyrannosaurus at the smaller end of their size scale, settling on individuals approximating the size of the 'Jane' specimen - about half the length of a fully-grown animal. There were also requests for contrasting blue and red colours on a male and female. I was happy to oblige, seeing as some degree of dimorphism is defensible for dinosaurs even at on half their full-grown size. Like mammals and non-avian reptiles, Mesozoic dinosaurs hit sexual maturity well before attaining fully ossified, completely grown skeletons and, for Tyrannosaurus, specimens in their early teens were probably reproductively active. In that sense, some features related to sexual behaviour might be expected in 'teenage' animals. Such individuals - better considered very young adults rather than large children - look rather different to their super-size contemporaries with their longer legs and more gracile build. Some of that is obscured here by the extensive feathering covering both animals (if you look very closely, you can just make out the arms of the sitting male), but their long legs at least show through.

The concept called for a a series of moths catching the attention of the male tyrant: initially one was ordered but, even at half-size, Tyrannosaurus is pretty big, so a few more were added to make them more conspicuous. My initial thought was to use butterflies rather than moths for the role of the lepidopterans, but I was surprised to learn that butterflies don't appear in the fossil record until well after the K/Pg event. Moths have a fair, if not especially extensive Mesozoic record, so they seemed a safer bet. They certainly add an air of tranquility to the scene not featured in a lot of theropod art: well done to Chidumebi for an excellent idea.

There'll be more output from the '£100 palaeoart offers' soon, although note that the offer is now full - over-full, in fact. There's some great ideas which I'm hoping to do justice to, so thanks to all who got their orders in - the offer sold out very quickly. If you didn't manage to get something to me on time, prints are still available - wittonprints@gmail.com is the address to contact for them.

Gower et al.'s Garjainia madiba: yes, the head is that big 

Gargainia madiba sp. nov., South Africa's newest erythrosuchid. From Gower et al. 2014.

Art number 2 is a life restoration of a new species of Early Triassic stem-archosaur, the erythrosuchid Garjainia madiba, described by David Gower and colleagues in this week's PLoS ONE. Unearthed in South Africa and named for Nelson Mandela ("Mr Mandela was known affectionately as 'Madiba'" - Gower et al. 2014), G. madiba has been making surprising ripples on Twitter and Facebook because of its rather enormous head. I say surprising because, for an erythroshucid, G. madiba is fairly typically proportioned - so far as anyone can tell, anyway. We don't have anything like a complete skeleton for G. madiba, although many aspects of its anatomy are represented in fragmentary specimens. It is currently distinguished from its relatives by fine anatomical details, perhaps the most notable being its large postorbital and jugal bosses of unknown function (best seen in the reconstructed anterior aspect, above). The discovery of more substantial G. madiba fossils may reveal more obvious distinction from other erythrosuchids, but, for the time being, the best we can do reconstruction-wise is show G. prima with a madiba upgrade package. Still, given how similar the two Garjainia species seem to be, this does not seem unreasonable.

Restoring Garjainia was a lot of fun because it forced a 'back to basics' approach to the artwork where David Gower, Richard Butler and I spent a lot of time discussing proportions, muscle distribution and posture. Many fossil animals - dinosaurs, pterosaurs, etc. - have been restored so often that the basic foundations of their anatomy are very well known, but this is not so for Garjainia and other erythrosuchids. A personal revelation to come from this process was evidence for enlarged areas of axial musculature on erythrosuchid skeletons, indicated by the rather tall neural spines of their necks and backs. This might give some insight into how their large heads were supported: a particularly well-developed, strong set of axial muscles. The posterior faces of their skulls are also wide and robust, providing space sufficient to anchor powerful neck muscles. But erythrosuchid anatomy was likely not held together only by brute strength: there's also some clever biological engineering at work. Like many archosauriforms with huge-looking heads, their skulls are more gracile and lightweight than they first appear, actually being fairly narrow for much of their length and riddled with fenestrae. We tried to show the former in our anterior aspect reconstruction: note how slender the snout of the animal is compared to the cheek region. The result is a head which is undeniably large, but probably much more manageable than it first seems.

For a lot more on Garjainia and other erythrosuchids, including the life restoration in situ, full descriptions of G. madiba anatomy and revisions to the diagnosis of the group, Gower et al. (2014) can be read here (hurrah for open access!). Thanks to David and Richard for bringing me on board, and congrats to them on the paper.

Coming soon: small, brown Mesozoic mammialiaforms! Yes, they are exciting. Really.

Reference

  • Gower, D.J., Hancox, P.J., Botha-Brink, J., Sennikov, A.G., & Butler, R.J. (2014) A New Species of Garjainia Ochev, 1958 (Diapsida: Archosauriformes: Erythrosuchidae) from the Early Triassic of South Africa. PLoS ONE 9(11): e111154. doi:10.1371/journal.pone.0111154

Friday, 7 November 2014

Prints, custom palaeoart, and antisocial Triceratops

Hey now - look at this: there's a way to buy high-quality prints of my artwork, and it's dead simple. Drop me an email at wittonprints@gmail.com with your requirements, pay off the invoice, and wait for your prints to arrive - hopefully within a week or so of order confirmation. Prices, sizes and all are discussed over here.

To celebrate this occasion, I'm also offering a limited number of über-cheap palaeoart commissions for private clients:


Yep - your own palaeoartwork, a print and delivery for just £100, which is a stupidly cheap price for original artwork. Full details (including a few important conditions) are here. As you may expect, I can't sustain working at that price for long. For that reason, there's only five of these deals being offered, and at time of writing, three of these deals have been taken. If you want in, don't delay. Don't despair if you miss this deal but would still like your own commission: drop me a line and we might be able to work something out.

Finally, because things have been a bit quiet about here for the last month or so, here's something to fill the void: a monochrome bristly Triceratops horridus, the dromaeosaur Acheroraptor temertyorum, and an interaction inspired by the wise, yellow philosophy of The Simpsons.

"...and like people, some [animals] are just jerks."

Apologies for yet another short post. Coming soon (when I'm allowed to publish them): Mammaliaformes! Heaps of pterosaurs! Deinonychus! Diminutive tyrannosaurines! And perhaps other subjects too!

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.