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Wednesday, 31 July 2013

Pterosaurs: The Natural History Museum Talk, September 2013

HyPtA D does the NHM logo. What's a HyPtA D? You need to buy Pterosaurs to find out, or attend the Pterosaurs NHM event in September. HyPta D image from Witton (2013); NHM logo borrowed from here.
Those of you with long-term memories may recall that, this September 10th (2013), the critically-acclaimed tome Pterosaurs: Natural History, Evolution, Anatomy is being celebrated with a public lecture at none other than the Natural History Museum, London. Details of the event have now crystalised and been made public over at the NHM's website. The talk will take place at 19:00-20:00 in the Neil Chalmers Seminar Room and cover all things pterosaurian: our changing understanding of these animals since their discovery, current ideas on many aspects of their palaeobiology, lots of palaeoart and photographs of specimens and, no doubt, some over-the-top PowerPoint animations which I'll spend hours tweaking for no obvious benefit. I'll do my best to keep to time (I have an excellent track record for punchy, concise talks, honest) so I can field questions at the end of the talk.

Note that the event is for NHM Members Only, will cost £5.50 per ticket, and booking is required. Details about membership with the NHM can be found here, and further information on the event and NHM memberships are available from your telephone, at +44(0)20 7942 5792.

I'm already looking forward to this, and hope to see many of you there.

UPDATE: I've just realised that the NHM's Lorna Steel, a pterosaur worker herself, is giving a behind the scenes tour of the NHM's extensive pterosaur collections on the same day as this talk (10/09/13) for NHM members, also for a mere £5.50. It seems that, if pterosaurs are your thing and you're an NHM member, you'll really want to be in London on the 10th of September.

Reference

  • Witton, M. P. 2013. Pterosaurs: Natural History, Evolution, Anatomy. Princeton University Press.

Tuesday, 30 July 2013

Engaging my Disacknowledgement

Tupandactylus imperator, a rat, and the Disacknowledgement. Not in that order. From Witton (2013).
Weirdest thing happened today: I finished two planned bits of work ahead of time (I know. I'm scared too!). That doesn't mean I'm off the hook work-wise. I was away last week (hence the lack of a fresh post) and catching up is making for a very hectic few days, but the fact that two bits of work were finished bang on time for an afternoon tea break means I've got time to slip in a quick bit of blogging without the usual guilt trip. We'll have to keep it brief, though, and discuss the rather straightforward image shown above.

Rather obviously, this image is a play on those most standard of palaeontological artworks, the extinct-creature-human-scale diagram, in this case showing the flamboyantly crested tapejarid pterosaur Tupandactylus imperator and a fully-fleshed Homo sapiens instead of a silhouette. Those who've read my book, Pterosaurs, may recognise this image from page 221. Note that the Tupandactylus soft-tissue crest is convex along its posterior margin instead of concave, as it's often been depicted. New fossils, such as those mentioned in Pinheiro et al. (2011), suggest that this 'fuller' crest is more likely than the concave crest indicated by the T. imperator holotype (Campos and Kellner 1997). The mandible shape also follows the specimen described by Pinheiro et al. (2011) rather than, as in most depictions of this animal, a generalised tapejarid mandible based on closely related species. Believe it or don't, virtually all that's known for certain of T. imperator is skulls, with only two specimens preserving mandible remains. Tapejarid skeletons without skulls are known from the Tupandactylus-bearing Crato Formation, and some of them likely represent bits of T. imperator itself, but we can't be certain of this until skeletons with associated cranial remains are recovered. Until then, we'll have to be satisfied with the revelation that T. imperator has chin big enough to scare even Kurt Russell, and wait for further discoveries. Be sure to check out this image of Tupandactylus navigans, another Crato pterosaur with a penchant for elaborate headgear, for more information on this genus.

But enough about that
What makes this picture more unusual than many like it is that it depicts an actual, real-life person who I happen to know very well, and anyone who's read Pterosaurs will also be familiar with. Here's where she's mentioned at length, from the 'Acknowledgements' page. She got her own section and everything.
Disacknowledgement
Finally, although customary in book acknowledgements to honor those who help steer projects to completion, it seems unfair to not mention the tremendous negative impact on this project made by Georgia Maclean-Henry. As the single most destructive force against this work, she took my attention from this project so frequently that we ended up moving in with each other halfway through the writing process and have ended up making some sort of home together. She continues to distract me from all kinds of work to this very day and, frankly, I could not be happier about it.
So yes, here she is. The Disacknowledgement herself. The 'single most destructive force against this work', and many others. I chose this picture to post now because today is the 2nd anniversary of the aforementioned moving in with my Disacknowledgement. I'm not normally one for noting or making a big deal of such things (as the Disacknowledgement knows all too well), this ties in with a more important recent event: the Disacknowledgement agreed to marry me when I asked her last week, which is all very exciting and I'm rather over the Moon about (before anyone asks, there were no knees involved, but there was a breccia, not to mention a kick-ass grey seal sighting moments before. He was huge!). Seeing as this image puts me in a good (and probably fairly unique) position to broadcast this happy fact while clinging to some sort of palaeontological relevancy, there seemed no better way to spend this brief teabreak. Speaking of which, said break ended quite a few minutes ago: best get on with other things, including hoping that the Disacknowledgement doesn't mind being referred to as 'the Disacknowledgement' all the time. Sorry dear. 

References
  • Campos, D. A. and Kellner, A. W. A. 1997. Short note on the first occurrence of Tapejaridae in the Crato Member (Aptian), Santana Formation, Araripe Basin, Northeast Brazil. Anais-Academia Brasileira de Ciencias, 69, 83-88.
  • Pinheiro, F. L., Fortier, D. C., Schultz, C. L., De Andrade, J. A. F. and Bantim, R. A. 2011. New information on the pterosaur Tupandactylus imperator, with comments on the relationships of Tapejaridae. Acta Palaeontologica Polonica, 56, 567-580.
  • Witton, M. P. 2013. Pterosaurs: Natural History, Evolution, Anatomy. Princeton University Press.

Wednesday, 17 July 2013

The Golden Age of Palaeoart?

Polacanthus foxii, a Lower Cretaceous ankylosaur from the Wealden of southern Britain, trying to shake some tiny birds off his nose as he strolls around a knoll of horsetails. Prints of this image are available.
It's a bad time for many industries, communities and institutions at present. Economies have crashed around the world, money for scientific research and artistic projects is at an all time low, education and human rights are being challenged by extreme social movements and the global biosphere is in crisis. To make matters worse, there's not even anything good on TV to take our minds off it all. But all is not lost. At least one institution, and likely one that folks reading this will care about a lot, is thriving. Indeed, it may be a veritable Golden Age for this industry, creatively at least, and there's no sign this boom period is going to end soon. I'm talking, of course, about palaeoart.

The recent history of palaeoart has been pretty interesting. We've seen the publication of several new books which are, for various reasons, likely to be considered seminal palaeoartistic works in years to come. New philosophies to palaeoart have emerged, and, all the while, the internet palaeoart community continues to grow and evolve. It's not only these developments which have helped palaeoart blossom particularly brightly in recent years, however. The advancement of new technologies, as well changes to academic publishing models, have also help usher in this wave of palaeoartistic splendidness. Some of these developments may sound a little humdrum, and some may be so obvious that we've not really sat to think about them before, but they may well make today one of the best times ever to be practising the art of reconstructing extinct organisms.

The Future, now!, and what it means for palaeoart
We'll start at the most fundamental end of palaeoart procedure: acquiring reference material. This has long been a problem for palaeoartists. Because palaeoart has an obvious firm rooting in palaeontological science, no self-respecting palaeoartist begins their work without developing an understanding of the anatomy of their target species. This typically involves working from scientific texts which have been, classically, hidden away behind publisher paywalls, unavailable to anyone without access to a university library, an online subscription to their services, or unwilling to part with obscenely-large sums of money for a single pdf download. There have always been ways around this - emailing authors, asking connected friends for photocopies or pdfs - but there's still an initial barrier to hurdle before work is even started.

The sign of better times. From Wikimedia Commons.
Happily, these walls are starting to crumble. The Open Access movement, which makes scientific literature available free to everyone, everywhere, has taken the academic world by storm, and even the greediest publishers are being forced to make their archived material more readily available. The battle for entirely free scientific literature is not yet over, but its victories are already making the life of palaeoartists far easier: high-quality reference material is increasingly often only a click away. It's not just the availability of literature which is a boon, either. New, online-only journals have thrown aside pesky limitations on figure numbers and image quality, permitting publication of numerous, top-quality illustrations for reference. Sometimes, we even get spinny-rotatey movies of CT scans to work from, showing anatomies in almost any view we could desire. As a bonus, the digital format of this information makes it easy to zoom up to tiny details which would be lost in print publications, allows for easily compiling our own anatomical reference sheets, and makes tracing anatomies for skeletal reconstructions infinitely easier than it's been in the past.

It's not just scientific papers that are an increasingly accessible resource, either. Dedicated websites committed to archiving the anatomical information craved by palaeoartists are becoming more plentiful. Sites like Digimorph, the Witmerlab pages, and the Bird Skull Collection are full of detailed graphics of animal anatomy of both extinct and modern species, and they're entirely free to access. Even Wikipedia is doing a fairly good job at providing references for palaeoartists. The excellent image of the sacral shield of Polacanthus, below, was sourced from the Wikipedia entry for that species for use the reconstructions adorning this post, for instance, and there's a lot more where that came from. Add this the increasing wealth of information scientists are putting online through blogs, podcasts, media releases and Youtube channels, and palaeoartists are on considerably better ground for finding reference material than we were even a decade ago.

 Woodward's 1881 depiction of the Polacanthus foxii sacral shield. From Wikipedia.
By palaeoartists, for palaeoartists
It's not only the scientific community that's feeding the blooming palaeoart scene. Several authors, many of them world-class palaeoartists themselves, have recently been producing easily-accessed works which are almost solely designed as references for fellow palaeoartists. I'm referring, of course, to the digital and printed works of the likes of Gregory Paul, Scott Hartman, Jaime Headden, Mike Hanson, and others. These chaps have published extensive libraries of anatomical orthographics for numerous fossil species, made suggestions about the most appropriate ways to reconstruct extinct anatomies, and generally helped artists transition fossil bones to restored animals significantly in recent years. (Note that a lot of Paul's guidance in this area pre-dates the Internet, and has mostly been published in books and magazines. Pdf versions of these articles, including his seminal 'rigorous guide' to dinosaur reconstruction from 1987, are available from his website). Matthew Martyniuk has also been contributing to this area recently, his excellent guide to Mesozoic birds (Martyniuk 2012)* and website detailing approaches to reconstructing avialans and their immediate ancestors. Elsewhere, I made a stab at providing a few helpful pointers to reconstructing pterosaurs in my own book, with some text and graphics specifically targeted at palaeoartists (Witton 2013). Even non-artists, like the guys behind Tetrapod Zoology and SV:POW!, are getting in on the act, regularly commenting on the possible life appearance of their extinct subjects and providing constructive criticism on certain bits of palaeoart.

The books, imagery and accessible discussions of these individuals will almost certainly inform palaeoartists for years to come. In particular, Paul's (2010) Field Guide to Dinosaurs is probably the most comprehensive collection of dinosaur skeletal reconstructions in a single volume, ever, and is of obvious utility for the high numbers of palaeoartists interested in Mesozoic dinosaurs. Pushing Paul (2010) as a key reference is, of course, complicated by Paul's insistence that his orthographics are not to be used as reference material by other artists. I must admit to finding this request a little odd and I suspect it's mostly falling on deaf ears. Still, however you want to use it, Paul's book, and other recently published resources like it, are invaluable resources for palaeoartists, and make it easier than ever for everyone to get basic anatomical data for their subject matter.

Taking it to strange new places
Is there any reason to think our conveyance of palaeontological subjects has improved in recent years? This is very much a matter of opinion, but I think it has, for some species at least. I've got to stress that this isn't because modern artists are more talented than their forebears. It's because modern palaeoartists seem to have finally got a handle on the rather dramatic new ideas and data that have coming our way for the last few decades, which has helped make newer depictions of certain species a little more convincing than those that came before. For instance, we've been bombarded with the discoveries of feathers on numerous type of non-avian dinosaurs, new considerations of soft-tissue masses (e.g. pterosaur limb musculature, dinosaur caudofemoralis mass) and novel ideas on the locomotory habits and postures of many species. That's a lot to take in and regurgitate into an image. It's not only changing scientific opinions which have altered the way we restore the ancient world, either. Radical shifts in palaeoartistic culture have also occurred, such as the well documented (including here) move away from overly conservative and 'shrink-wrapped' depictions of fossil species. It's been a changeable and dynamic few decades for palaeoartists, and I think it's understandable that it's taken a little time to work out what all this new information and philosophical changes equate to in artwork.
Perceptions of pterosaurs have changed a lot in recent years. The thin, lanky azhdarchid on the left didn't look odd in 2006, but looks positively anorexic compared to more recent reconstructions (right, from Witton 2013).
The upshot of this, in my opinion at least, is reconstructions of several species - including well-known taxa - have only started to appear in the last few years. This particularly applies to animals like maniraptoran dinosaurs and pterosaurs, species which have been classically portrayed rather outlandishly because of their unusual anatomy and some outlandish approaches to their depiction (Slasher Poses, I'm looking at you). I'm astounded at the convincingness of some of Matt Martyniuk's reconstructions in his Field Guide to Mesozoic Birds, for instance. His oviraptorosaurs look like elegant creatures painted from life, instead of the incredibly goofy forms we're more familiar with. The same applies to Emily Wolloughby's bouncy, eutherian-chasing Velociraptor, John Conway's famous squatting Therizinosaurus and many others. These animals make a lot more sense to look at now now, as do a lot of other restored ancient creatures. My feeling, at least, is that these very recent interpretations of these animals are closer to reality than anything we've seen before, and that can only be a good thing.

As an added bonus, an almost postmodern approach to palaeoart has emerged (crystallised, of course, in All Yesterdays [Conway et al. 2012]), which helps avoid the many tropes and clichéd artwork we see again and again. The result is that modern palaeoart may not only be more accurate to life, but is more interesting to look at. I almost get the feeling that there's greater confidence in palaeoart than there used to be. Because we know more about the animals, more about the most convincing ways to depict them, and more about our own collective foibles, palaeoart seems to be moving confidently into new and interesting areas. Again, I stress that I'm not downplaying the quality or importance of other artists and previous work - as with any artform, palaeoart is a product of its history - but it feels that a lot of modern palaeoart is trying hard to break into new territory. And that's great.

Being seen and heard
Of course, all of this work would be for nothing if it weren't seen. As a child living in the pre-Internet age, the only way I'd see new palaeoart was though purchasing new books, or sometimes in magazines and newspapers. New bits of artwork were rare, important events. The situation nowadays couldn't be more different. Most palaeoartists have online galleries or blogs (or both), and they post new artwork to Twitter, Tumblr, and Facebook. We don't just see new press release artwork because it's been a slow news day: if a new bit of artwork is released, there's a good chance we'll see it. What's more, the artists themselves are no longer simply represented by squiggled names in the corner of an image: social media allows them to introduce and comment on their work. While most of this is happening online, it does, on occasion, still happen in print: see Dinosaur Art: The World's Greatest Palaeoart (White 2012), and Douglas Henderson's new book detailing his early work and inspirations (here) for examples. I think this is a terrific change from simply waiting for new books to be released. There's a much greater sense of community, greater familiarity with each other's work, and very liberal exchange of ideas.

A closer look at the Polacanthus from up top. He's nothing to do with anything here, just livening up the post.
The Internet has also revealed how much terrific artwork is being done by up-and-coming artists. The only palaeoart we routinely saw in the 90s was that of a few masters: Henderson, Hallett, Sibbick, Paul and so forth. Nowadays, we know of have a much broader range of individuals producing art at very high levels. The growing number of palaeoartists seems to have ruffled a few feathers among some established profressionals who have found a lot of their work being outsourced to others (see this thread on the Dinosaur Mailing List) but, on reflection, I think growth in the palaeoart community is inevitable. Greater availability of palaeontological information, the rise of the online palaeontological community, the increasing availability of palaeoartistic guidance, the affordability of digital painting setups and the ease of uploading content online are all contributing factors here. This does mean greater dispersal of the available work among more individuals, but I'm not sure there's much we can do about that.

Besides, this greater range of artists has to be a good thing, and not just because it we get to see more palaeoart. It also allows for a wider range of styles and media than we're used to. Most palaeoart I remember from my childhood was attempting to rival photographs in detail, but a lot of modern work offers more stylised - more artistic, even - interpretations of ancient life. This goes hand-in-hand with a range of media being used. Modern palaeoart is not only being produced by traditional painting and sculpture, but also by compositing photographs, 3D digital modelling, digital painting, vector art and combinations thereof. It's great seeing how these diverse media bring ancient worlds to life in different hands, and makes working within the palaeoart community a generally more interesting and inspirational place.

On top of that, the palaeoart community itself is proving to be an active and interesting one, with events like the open source Life Galleries of ArtEvolved (sadly, these galleries are coming to an end soon after a 4 year run), palaeoart competitions at Love in the Time of Chasmosaurs and from the All Yesterdays chaps, and even pooling resources to generate it's own independent products. And this doesn't even scratch the surface of palaeoart coverage and events in social media, not the mention the palaeoartist meetings and gatherings that now frequently happen at conferences. We only have to look to the rapid uptake and discussion of All Yesterdays as a good example of how lively and active the online palaeoart community is. How successful would that project have been without the online palaeoart community?

So there you have it
And that's why, all told, I think we're living in a 'Golden Age' of palaeoart. There's more of it, the artwork we have is generally better informed because of improved access to reference material and guidance from experts, we've (finally) got a a handle on ways to reconstruct some stranger ancient species and, to boot, developed a wide, friendly community of excellent artists. It's a good time to be a palaeoartist, then, and long may that continue.

References
  • Conway, J., Kosemen, C. M. and Naish, D. 2012. All Yesterdays: Unique and Speculative Views of Dinosaurs and Other Prehistoric Animals. Irregular Books.
  • Martyniuk, 2012. A Field Guide to Mesozoic Birds and Other Winged Dinosaurs. Pan Aves.
  • Paul, G. S. 1987. The science and art of restoring the life appearance of dinosaurs and their relatives – a rigorous how-to guide. In Czerkas, S. J. and Olson, E. C. (eds) Dinosaurs Past and Present Vol. II. Natural History Museum of Los Angeles County/University of Washington Press, pp. 4-49.
  • Paul, G. S. 2010. The Princeton field guide to dinosaurs. Princeton University Press.
  • White, S. 2012. Dinosaur Art: the World’s Greatest Paleoart. Titan Books, London.
  • Witton, M. P. 2013. Pterosaurs: Natural History, Evolution, Anatomy. Princeton University Press.

Saturday, 13 July 2013

Something R'lyeh different

Detail of "Mark Witton's greasy, flowing mass", for Matt Wedel's Collect Call of Cthulhu
If my Facebook and Twitter feed tell me anything, it's that folks with interests in palaeontology are also very interested in science fiction. Chaps who liberally discuss bird origins and tyrannosaur feeding palaeobiology are likely to also discuss how many tribbles you can stuff into a Jefferies tube or which Imperial Walker would be best for car-pooling to work. Given that a lot of modern science fiction teeters under the weight of ideas borrowed from early science fiction authors, I'm going to take a wild guess that a lot of palaeofiends have, at one time or another, traced these sources back to one of the cornerstones of modern sci-fi: the nightmarish, slimy and tentacle-rich mythos of H. P. Lovecraft.

Matt Wedel, best known in palaeontological circles as a crusader of sauropod vertebrae, certainly has. Over at Echo Station 5-7 he's been musing on the nature of Lovecraft's seminal creation, Cthulhu, and inviting submissions of artwork rendering his hideous visage. A keen emphasis has been made on entrants avoiding the traditional representation of Cthulhu as a guy with squid head through either style or biological interpretations, which I agree with 100%. Lovecraft's descriptions of Cthulhu are undeniably vague, but his suggestion of a greasy, dripping, and ambiguous being is a million miles away from the beefy, green anthropoids we see striding around all too often. Indeed, even Lovecraft's own sketches of Cthulhu seem quite wide of his text:
Cthulhu takes five in this sketch by H. P. Lovecraft himself. Borrowed from the Lovecraft EZine.
Given that I'm not adverse to dipping my toes in Cthulhu mythos myself, I couldn't resist joining the fun. I've had an old, half-finished painting of Cthulhu lying dormant, dreaming, on my hard drive for well over two years, so saw Matt's open invitation as the impetus to wake him up, finish him off, and send him in. The results can be seen in part at the top of this post, but you need to head to Echo Station 5-7 to see the rest. Because I was apparently cursed to write at length about pretty much anything I create in a past life, there's also a typically lengthy explanation for the decisions I made in the rendering process.

If Lovecraftian things are up your street, you also owe it to yourself to read the comments from regular palaeoblog contributors on what they think makes a good Cthulhu, here, here and here. They're not only great demonstrations of how diverse the interpretations of vaguely-understood literary beings can be, but offer some great speculative biology because of the informed scientific backgrounds of each commenter. The discussions at Matt's blog have also spawned an interesting essay on the ecological strategies used by Lovecraft's beings, based on vernal pools, penned by Heteromeles at Putting the Life Back in Science Fiction.

All good stuff, and I've thoroughly enjoyed being part of it. Regular programming - art of old dead things - will be resumed shortly.

Thursday, 11 July 2013

Rhamphomummies and zombie skim-feeders

A 'mummified' Rhamphorhynchus muensteri entangled with the spear-like rostrum of Aspidorhynchus acutirostris, presumably reflecting a failed predation effort by the latter. Painting of a privately-held specimen, used with permission.
A few months ago, Frédéric Weber asked me to render two images of a spectacular, unpublished specimen from the famous Jurassic Solnhofen deposits of Germany. It showed a rare association between two animals: the non-pterodactyloid pterosaur Rhamphorhynchus muenesteri and a ganoid fish, Aspidorhynchus acutirostris. Associated fossils are not uncommon in some deposits, but they are extremely rare in the Solnhofen Limestone. Fred wanted images of this Rhamphorhynchus/Aspidorhynchus association to illustrate a recent article in Fossiles magazine devoted to pterosaur specimens from Solnhofen (Weber 2013), with this particular specimen being all the more important because the pterosaur's body outline has been preserved by growths of calcite crystals rather than decaying away. 'Mummified' pterosaurs like this aren't entirely unheard of, but they remain rare and are exciting for what they tell us about soft-tissue distribution. Making this specimen even more spectacular is the preserved wing tissues of the pterosaur and the perfect state of the neighbouring Aspidorhynchus. Fred wanted to show the exquisite preservation of the specimen but was asked not to reproduce photos by its owner, so he asked me to do my best at reproducing it in a few images. The article containing this image is only the latest in a series on pterosaurs produced by Fred and, even if you cannot read French, they're well worth tracking down for their awesome imagery.

Those of you with ears to the ground of pterosaur research will know that this specimen is not one of a kind. Another, WDC CSG 255, was described by Eberhard 'Dino' Frey and Helmut 'King of UV' Tischlinger back in 2010, and at least three others are known. Given how rare such associations are in Solnhofen desposits, the repeated association of these animals implies some common explanation for their co-preservation. The rationale provided by Frey and Tischlinger (2010) sounds pretty convincing to me. They suggest that Aspidorhynchus frequently predated Rhamphorhynchus but, because the pterosaur was a little too big and gangly for its mouth, it's wing membranes became entangled on the fish's rostral spar or teeth and could not be swallowed. In efforts to shake the pterosaur loose, some Aspidorhynchus accidentally entered the anoxic bottom waters of the Solnhofen lagoon and, well, the rest is pretty self explanatory. It's quite probable that these predatory events were accidental, which may explain why many Aspidorhynchus specimens preserve fishy gut content, but none show successfully ingested pterosaur bones.
The Rhamphomummy and it's attacker in full. Line drawing of a privately-held specimen, used with permission.
But that's not all
Remarkably, one of these associations provides some insight into what brought the Rhamphorhynchus into striking range of Aspidorhynchus. The throat region of the WDC CSG 255 Rhamphorhynchus is full of undigested fish bones (probably Leptolepides) which suggest it was foraging for food just before it was grabbed by an Aspidorhynchus(Frey and Tischlinger 2010). The fact that at least some Rhamphorhynchus were likely foraging in the immediate interim before being attacked has, of course, raised interest in the foraging method utilised by Rhamphorhynchus because it may be linked to the attacks from Aspidorhynchus. Frey and Tischlinger (2010) suggest two options here. Firstly, Rhamphorhynchus may have grabbed fish from the water surface by dip-feeding, and was then grabbed. Unlikely, they say, because this wouldn't give the Aspidorhynchus enough time to grab the pterosaur once it disturbed the water. So a more likely idea, they suggest, is skim-feeding.
"Skimming... took time and resulted in a significant signal of turbulence, when the mandibular rostrum ploughed through the silent water surface. Such turbulences attract all kinds of fishes and are also were easily detectable for an Aspidorhynchus. Furthermore, the vane at the terminus of the long tail of the pterosaur could have contacted the water surface too due to the extremely low surface approach with a flight altitude of no more than 50 mm. Large Aspidorhynchus thus could grab a skimming Rhamphorhynchus by just raising the head through the water surface. The specimen presented here strongly suggests that Aspidorhynchus actually did exactly this." Frey and Tischlinger 2010, p. 4. (my emphasis)
Skim-feeding, we meet again
Yes, skim-bloody-feeding. A number of pterosaur workers - myself included - view the skim-feeding pterosaur hypothesis as highly problematic, based on very superficial science, and a complete non-starter based on simple comparative anatomy. Despite this, this idea is incredibly tenacious within pterosaur literature. Skim-feeding was widely considered a viable forging method for pterosaurs up until the mid-2000s (e.g. Wellnhofer 1991; Hazlehurst and Rayner 1992, Kellner and Campos 2002; Unwin 2005) when, under a hail of scientific bullets, several authors suggested it was implausible for numerous reasons (Chatterjee and Templin 2004; Ősi et al. 2005; Humphries et al. 2007; Witton and Naish 2008). Humphries et al., the first (and only) dedicated study of skim-feeding in pterosaurs inflicted the deepest wounds, using biomechanical testing and comparative anatomy to conclude:
"Both modelling the energy requirements of skimming pterosaurs and analysing their osteology casts serious doubt on the ability of pterosaurs to habitually skim-feed. Although our physical modelling suggests that small pterosaurs may have been energetically capable of skimming, there is no anatomical evidence to assume that Rhamphorhynchus or any other small pterosaurs were skimmers." Humphries et al. (2007), p. 5
I was part of that study (my first publication, nonetheless) and thought that, with other authors suggesting similar misgivings about the idea, that skim-feeding had been stopped dead. Like the foraging hypothesis equivalent of a freakin' zombie, it has since risen again with more questionable science to prop it up (Stecher 2008; Frey and Tischlinger 2010; Averianov 2013). Even attempts to subtly downplay the likelihood of pterosaur skim-feeding in blogs ("Die you skim-feeding bastard, die!") haven't got the message through. What will it take to down this thing? Here's another go, then, at explaining why I, and others, think this hypothesis is a complete non-starter and should be abandoned.

Where's the beef?
Firstly, there's never been an in-depth, detailed study suggesting skim-feeding was likely in any pterosaurs. So far as I can tell, the link between skim-feeding and pterosaurs started with throwaway comments by Marsh (1876), who suggested the mandible of Pteranodon was reminiscent of the lower jaw of modern skimming birds. Since Marsh, nearly 20 articles have suggested pterosaurs may have skim fed, but none have really added much to his idea. Most simply suggest, with varying degrees of certainty that pterosaurs of all kinds (rhamphorhynchids, 'campylognathoidids', ornithocheirids, dsungaripterids, thalassodromids, azhdarchids are candidates) were skim-feeders based on very superficial anatomical comparisons with modern animals. Kellner and Campos (2002) did the most thorough job with Thalassodromeus, but even that was a fairly brief comparison between their new taxon and modern skimmers that was very restricted by it's publication in the short-piece journal, Science. There's certainly never been anything published with sufficient quantified or even illustrative evidence to support skim-feeding in pterosaurs. It really seems that  pterosaur skim-feeding has become an established concept not because of its scientific credibility, but because of its longevity and popularity. Similar comments could be made about many established, 'common knowledge' ideas about fossil animals.

The skull and mandible of Rynchops niger in lateral view (A) and mandible in dorsal view (B). Note the extremely derived anatomy on every facet of this thing, all of which reflect skim-feeding habits. From Witton (2013).
The rather superficial science behind skim-feeding could almost be excused if it weren't for the extensive documentation of the lifestyle and functional anatomy of modern skimming birds. The exhaustive work (essentially a whole book) produced by Richard Zusi (1962) is a key reference here. It's widely known that, in the modern day, skim-feeding is only practised by a couple of bird species, all of which belong to the genus Rynchops. Thanks to several generations of ornithologists researching this animal, we know that Rynchops is specialised six-ways-from-Sunday for it's unusual habits. Check out the Rynchops skull and mandible, above, for instance. Virtually every facet, every joint and feature reflects it's lifestyle. This specialisation extends to its neck and flight style. Zusi (1962) noted a whopping 26 obvious morphological adaptations to skim-feeding, which are detailed in a handy cut-out-n'-keep guide below.
The result of these is that when handling a skimmer skull, even if you'd never seen one foraging, there's no doubt whatsoever about it's preferred habits. These birds need to be so specialised because, frankly, skim-feeding is a ridiculous way to feed. Dragging your lower jaw through a relatively viscous, obstacle-filled fluid at 16-32 kph and hoping to hit something you can eat isn't a particularly sensible approach to foraging. Skimmers can't even see what they're trawling into (Martin et al. 2007), and they regularly run aground in shallow mud or blunder into vegetation. On occasion, these impacts are severe enough to cause crashes or snap off the tip of the mandibular rhamphotheca (Potter 1931). Of course, evolution has a wonderful disregard for sense and logic, and skim-feeding behaviour simply promoted the development of impact resistant necks and skulls, with reinforced jaw joints and powerful jaw muscles. These include enlargement of their secondary jaw joints (a common avian feature; labelled as 'medial processes' on the diagram above), considerable reinforcement of the mandible and a broad neck base to anchor powerful, impact resisting neck muscles. Because the forces acting on Rynchops jaws during skimming are so high, skim-feeding birds have to pull their jaw muscles tight when foraging: the upper jaw is 'opened' via kinetic hinges at the mid-length of the skull. Biomechanical modelling of skimmer flight suggests skim-feeding flight is energetically demanding (Humphries et al. 2007), necessitating extremely streamlined lower jaw tissues along with abradable, rapidly-growing beak tissues to replace those worn away in accidents. Because skim-feeding impacts - desired or otherwise - pull the head into the water, skimmer necks are also unusually long and flexible. We could go on: these birds are fascinating case studies of adaptation.

Rhamphorhynchus mummy skull detail. A dorsoventrally slender mandible and a mouthful of teeth probably aren't the best way to approach skim-feeding.
With the mechanics of skim-feeding so well understood and its adaptations so obvious on animal skeletons, there's really no excuse for skim-feeding in pterosaurs to be so superficially considered. There's only so many ways for a flying tetrapod to trawl a mandible into things it hopes are food after all, so we should expect common adaptations between pterosaurs and Rynchops. Compare the skull of Rhamphorhynchus in the painting above, with that of Rynchops. Even in that crude approximation of its anatomy we can see the lack of of cranial reinforcement, the wimpy areas for jaw muscle attachment, and the bloody-great teeth where a knife-like skimming jaw should be. And yes, there are specimens of Rhamphorhynchus that show the jaw tip was extended with soft-tissue, but nothing like that seen in Rynchops (see image, above). The same arguments can be levelled at all other proposed pterosaur skim-feeders, even the animal named after it's alleged skim-feeding habits, Thalassodromeus (Kellner and Campos 2002). There are no convincing anatomical correlates for skim-feeding habits in any known pterosaur (Humphries et al. 2007; Witton and Naish 2008). This is almost certainly why pterosaurs with wingspans over 2 m (which, of course, is about the size of large Rhamphrohynchus) lack sufficient power output for skim-feeding (Humphries et al. 2007): their jaw shapes were never adapted for efficiently cutting through water. Smaller pterosaurs may be able to plough a short length of toothless jaw tip through water, but they'll be aching with the muscular exertion on their jaws, and in huge pain if they hit anything. I feel it would be remiss here to ignore the story behind testing streamlining in the Thalassodromeus jaw tip, which was so violently stressful that it broke the testing rig of the Humprhries et al. (2007) study. Back in 2007, I shared my recollection of what became known as the 'Thalassodromeus Flume of Doom':

Rather old and silly presentation slide. Based on real events.
In all the press accompanying the publication of Thalassodromeus, one worker is recorded as saying it must’ve looked like a ‘vision of hell’. Well, hats off to him: he was right. There was something unerringly terrifying about the massive jaw tip of this thing hurtling towards you at great speed. Maybe it’s because there was water everywhere. The moment Thalassodromeus began to skim, the whole rig started shaking manically, throwing water about like a possessed jetski and drawing worried glances from the crew. Notching the speed higher, the rig became more unstable and, to everyone’s surprise, the aluminium bar was even bent on one run. This was replaced and, eventually, the time came to set max speed: 25 kmph. The catcher, a nervous looking PhD student, was braced and ready. At the other end of the flume, the pterosaur-cyborg beast glared at him, the water eerily calm before the violence that would follow. “You ready?” asked Stu, and I gulped my affirmative. The winch was pulled. Suddenly, the beast was roaring down the runway. The room echoed with the inhuman screaming of its wheels on the track. The jaw was convulsing madly. Water crashed over the tank walls. Then the screaming stopped with a loud bang: the Thalassodromeus was airborne; the whole rig arcing through the air and spiralling forward - only milliseconds separated it from a watery grave. My clothes ripping against the metal tank and the waves pounding my body like Achilles in the River Scamander, I leapt forward and grabbed the plummeting contraption moments before it hit the water. We rushed the wounded rig from the flume to check its health: the aluminium bar was totally twisted, the electronics shot. The little blinking lights on the mechoreceptor faded to black. The rig lay dead in Richard’s arms. Stu called to the Heavens in anger. Dave cried. I was soaking wet. It was about then that we started wondering if ‘ocean runner’ was a name slightly too optimistic about the skimming capabilities of its owner. With testing brought to a dramatic but premature end for the day, we retired for back massages and herbal treatments from attractive Scandinavians to recover from the ordeal. Such is the life of courageous university researchers. (link to original)
Put together, these three reasons - the lack of a good studies in favour of pterosaur skim-feeding, the fact we know so much about modern skim-feeders, and the overwhelming evidence against skim-feeding in pterosaurs - are why I find it a tiny bit irritating that this idea is still being discussed as plausible. It just seems, I dunno, that our ideas should be moving on or something.

Night of the living skim feeders
If skim-feeding in pterosaurs is so objectionably flawed, why won't the idea be politely resigned to history? I predict four causes.
  1. It's an established idea, even if it's not based on any particularly rigorous science. Established ideas take a long time to overturn even if evidence to the contrary is strong. 
  2. Pterosaurs were flying animals. For some palaeontologists, this equates to them doing everything in flight.
  3. There may be unawareness concerning how specialised Rynchops is for skim-feeding, and how unique its morphology is, even among birds. Anyone thinking of proposing skim-feeding habits for pterosaurs really should familiarise themselves with the work on Rynchops lifestyle first, and particularly Zusi's 1962 treatment.
  4. Life of the past is frequently considered to be outlandish and overly dynamic (also see discussion of animal poses in palaeoart, here and here). This is perhaps why, when Frey and Tischlinger (2010) considered how a pterosaur may have been attacked by a marine predator, boring ideas like the pterosaur swimming or floating weren't considered*.
*Before anyone asks, there is at least trackway evidence suggesting pterosaurs can swim (Lockley and Wright 2003) and new take off models suggesting water launches weren't difficult (Habib and Cunningham 2010), so let's not hear anything about waterlogging of wing membranes or whatever.

Of course, none of these are particularly defensible. We simply need to stop trotting skim-feeding pterosaurs out at what almost seems like any given opportunity. There's never really been anything to it, and until sufficient evidence - like a pterosaur fossil bristling with skim-feeding adaptions - comes to light, the idea's as dead in the water as the Aspidorhynchus and Rhamphorhynchus we discussed on the way in. I'll take that arriving at conversational full circle as a good place to stop.

Next time (possibly): Space Year 2013: The Golden Age of Palaeoart?

References
  • Averianov, A. O. 2013. Reconstruction of the neck of Azhdarcho lancicollis and lifestyle of azhdarchids (Pterosauria, Azhdarchidae). Paleontological Journal, 47, 203-209.
  • Chatterjee, S. and Templin, R. J. 2004.  Posture, Locomotion and Palaeoecology of Pterosaurs. Geological Society of America Special Publication, 376, 1-64.
  • Frey, E. and Tischlinger, H. 2012. The Late Jurassic pterosaur Rhamphorhynchus, a frequent victim of the ganoid fish Aspidorhynchus? PLoS ONE, 7, e31945.
  • Habib, M. B. and Cunningham, J. 2010. Capacity for water launch in Anhanguera and Quetzalcoatlus. Acta Geoscientica Sinica, 31, 24-25.
  • Hazlehurst, G. A. and Rayner, J. M. 1992. Flight characteristics of Triassic and Jurassic Pterosauria: an appraisal based on wing shape. Paleobiology, 447-463.
  • Humphries, S., Bonser, R. H. C., Witton, M. P. and Martill, D. M. 2007. Did pterosaurs feed by skimming? Physical modelling and anatomical evaluation of an unusual feeding method. PLoS Biology 5, No. 8, e204.
  • Kellner, A. W. A. and Campos, D. A. 2002. The function of the cranial crest and jaws of a unique pterosaur from the Early Cretaceous of Brazil. Science, 297, 389-392.
  • Martin, G. R., McNeil, R. and Rojas, L. M. 2007. Vision and the foraging technique of skimmers. (Rynchopidae). Ibis, 149, 750-757. 
  • Ősi, A., Weishampel, D. B. and Jianu, C. M. 2005. First evidence of azhdarchid pterosaurs from the Late Cretaceous of Hungary. Acta Palaeontologica Polonica, 50, 777-787.
  • Potter, J. K. 1932. Fishing ability of the black skimmer (Rynchops nigra nigra). The Auk, 49, 477.
  • Stecher, R. 2008. A new Triassic pterosaur from Switzerland (Central Austroalpine, Grisons), Raeticodactylus filisurensis gen. et sp. nov. Swiss Journal of Geosciences, 101, 185-201.
  • Unwin, D. M. 2005. The Pterosaurs from Deep Time. Pi Press, New York.
  • Weber, F. 2013. Paléoécologie des ptérosaures 3. Les reptiles volants de Solnhofen, Allemagne. Fossiles. 14. 50-59.
  • Wellnhofer, P. 1991. The Illustrated Encyclopaedia of Pterosaurs. Salamander Books Ltd., London.
  • Witton, M. P. 2013. Pterosaurs: Natural History, Evolution, Anatomy. Princeton University Press.
  • Witton, M. P., & Naish, D. 2008. A reappraisal of azhdarchid pterosaur functional morphology and paleoecology. PLoS One, 3, e2271.
  • Zusi, R. 1962. Structural adaptations of the head and neck in the black skimmer Rynchops nigra Linneaus. Publications of the Nuttall Ornithological Club 3, 1-101.

Tuesday, 2 July 2013

Praise for Pterosaurs: Natural History, Evolution, Anatomy

Before there were pterosaur fossils, there were rotting pterosaur corpses. This here is the rotting skull of Dsungaripterus weii, one of the largest dsungaripteroid pterosaurs known. His eye socket seems particularly interesting for some reason. Full, uncropped version of this painting, from Witton (2013).
Time's been a bit short for the last week, which means I'm falling behind my ideal blogging frequency. What better way to catch up, then, than to have some others write a post for me? Pterosaurs: Natural History, Evolution, Anatomy has been released in the wilds for several weeks now, which means that reviews are starting to trickle in. I'm happy to say that all legitimate reviews of the book have come up very well indeed, and there's praise all around. But you don't have to take my word for it: summary statements and links to reviews are provided below, along with some additional artwork from the book, just for fun. In case you missed it, an overview of Pterosaurs content is provided here and via the shiny new Pterosaurs widget on the top right of the page. The nice folks at Princeton have also recently released samples of 12 double-page spreads of the book, so be sure to check those out if you've not seen a copy yet. Kindle and dead-tree versions of the book can be ordered from Amazon. On to the review summaries!
Witton’s combination of style and substance makes Pterosaurs a true treasure and an absolute must for anyone curious about the extinct flyers... If you’re truly invested in learning about pterosaurs, Witton’s book is a wealth of information that will be of great use to both specialists and curious general readers.
Brian Switek, Laelaps (National Geographic Phenomena)
This really is the ultimate guide to pterosaurs, providing us with a richer view of pterosaur diversity and behaviour than allowed in the two previous great volumes on the group (Wellnhofer 1991, Unwin 2005) and containing a substantial amount of review and analysis of pterosaur ecology and functional morphology.
Darren Naish, Tetrapod Zoology (Scientific American blog network)
Whatever the intent of the author, the book does succeed at a number of levels. While probably a tricky read for those very unfamiliar with fossils, it should be easily accessible for anyone with a passing interest in palaeo as well as providing a solid review of the whole of the Pterosauria that’ll be genuinely useful for researchers for many years. I’m sure I’ll be typing “Witton, (2013) stated….” quite a lot in the future and that, if anything, should be a good measure of how I rate this as a scientific text. Now go buy a copy and read it, it really is very good. 
Dave Hone, Pterosaur.Net
This book is both academically interesting and truly fun to read. That is a difficult balance to reach, but Witton does an excellent job of it by using a lighthearted, informal writing style in combination with a well-referenced, serious scientific review. An invaluable reference.
Michael Habib, endorsement at Princeton University Press 
(Mike's summary response as referee to the book text)   

Thalassodromeus manufacturing pterosaur feeding traces, which are known from a number of pterosaur tracksites. Was Thalassodromeus always this placid? Maybe not, according to imagery at this post. From Witton (2013). 


 
This book does a good job of summarizing several of the diverse arguments that fly — pardon me — around ...Witton walks a fine line between presenting a technical review and providing an introductory text for students unfamiliar with the group in question or students unfamiliar with scientific discourse at all. ... Recommended? Yes, with kudos.
Jaime Headden, The Bite Stuff 
Mark... presents the uncertainties of science but never shies away from making his opinion clear. [He] respects the complexities [of scientific writing] without allowing them to clump up the text. ... Mark isn’t the craftiest of illustrators, but I wouldn’t change a single of his drawings for any pile of slickness. Mark understands illustration, and he illustrates. ...  I can wholeheartedly recommend the book already."
David Mass, DRIP 
PTEROSAURS would make an excellent addition to any reference collection and especially that of an advanced (adult or young adult) lay-reader.
Greg Leitich Smith, GSL BLog 
I can tell you that it is not only a fascinating bit of text, its illustrations will leave you gaping in awestruck amazement.
John E. Riutta, The Well-read Naturalist   
I thoroughly enjoyed this book. Witton's style is rather informal, but his coverage of the subject is academically rigorous, and his excellent illustrations convey both his knowledge of and passion for his subject. It tells a great story of the history of extraordinary animals, and should appeal to anyone interested in science, let alone palaeontology. It is worth its cover prices for the illustrations alone, many of which are the work of the author and presented with a quirky sense of humour.
Richard Forest,  Amazon.co.uk book review

Just how do you make a pterodactyloid pterosaur? Follow these instructions, bake for an undisclosed number of millions
of  years, and viola! Preondactylus, Darwinopterus and Pterodactylus skeletals from Witton (2013).

Thanks very much to those who've taken time to review Pterosaurs or sing its praises online in blog comments and social media. An additional big thanks to those who've personally written to me to express their satisfaction with the book. Hammy as it is to say, it's really great to hear that so many people like it.

Next time (hopefully very soon): mummified pterosaurs (promise number 3 for that one) and the most tenacious of all proposed pterosaur habits.

Reference
    • Witton, M. P. 2013. Pterosaurs: Natural History, Evolution, Anatomy. Princeton University Press.