Monday, December 27, 2010

Low flying Pteranodon

There are far too few good pterosaur mounts in museums around the world, but admittedly with generally good reason. They are hard to model, there are few casts around, the interesting ones like Pteranodon are really quite big, and really you want them flying. That means mounting stuff on the ceiling which is difficult and even dangerous (well, public safety at least becomes an issue). And of course, much as I might loathe to admit it, they are just not as popular as dinosaurs. Still, there has been a slow but steady increase in the number of mounts like these turning up which is a good thing.

This particular one is in Eichstaett, and lovely it is too (thought the black Quetzalcoatlus above it is not half as nice). The mount is actually not far off the ground which make it easy to get a good look at it (I have seen an Anhanguera mounted about 5m off the ground in Frankfurt and you can barely see what is obviously a nice model) but the downside to this is that it's very hard to get far enough away to get the whole thing in frame, as the last photo shows.



Thursday, December 23, 2010

Tis the season of Pterodactylus

I've now managed to sort through most of my photos from my trip to the Solnhofen. That has resulted in me being able to put up some nice Pterodactylus photos over on my blog. So, since this site is just supposed to be about pterosaurs, I rather assume the readers would be interested. Here's a pair of special fossils, if for rather different reasons, and here's what happens to pterosaurs that really settle in Bavaria.

Thursday, December 16, 2010

Pterosaur mandibular fenestrae

So after that huge hiatus, suddenly P.net is back up and running and you get a raft of posts close together. Obviously as this is Dave again, I'm not going to totally recycle my posts form my own blog, but actively send you over there to read what I have already written. Still, this is an interesting paper because it tackles that terminally vexing problem of pterosaur origins.

The problem with specialising for flight is that it tends to require you remodel your skeleton rather drastically and for palaeontologists working just from bones, that can make it difficult to work out exactly which features are there, or are there but radically changed, or have gone. Thus while the pterosaur fossil record is pretty good in some respects, we have really struggled when it comes to working out their ancestors / nearest relatives from among the other reptiles. (Obviously we've narrowed it down a lot, but pinning it exactly is tricky).

One major character they have always seemed to lack is a mandibular fenestra, basically a hole in the jaw, which is otherwise present in many dinosaur and croc-like reptiles that pterosaurs are supposed to be related to. No fenestra, perhaps no close ties. But specimens both new-ish and old show that actually this might be present, and the discovery of various dinosaur relatives show some rather pterosaur like features. In short, the gap in our knowledge and the gap in the supposed differences in anatomy is starting to shrink.

If you want the full details, then head on over to the Musings where you can read part 1 and part 2 of my report on my new paper (with Sterling Nesbitt). Enjoy.

Monday, December 13, 2010

Research updates

Well Mark and Mike have been promising for a while to blog about their paper of last month, but noting has quite materialised as yet. Still, if you have missed it, it is freely available online here at PLoS one. However, they are not the only ones to have been pterosaur-ing of late. Friends and colleagues of the P.net team in Tamara Fletcher and Colin Palmer have both had recent papers out and were good enough to blog about them for me over on the Musings. Tamara introduces some new Australian material and talks about the difficulty of writing that first paper and Colin takes us through his work on pterosaur flight.

So hop over there and take a look. I'm just back from a trip to Germany including a visit to Helmut Tischlinger and Ross Elgin and will have some photos to come from that too.

Sunday, October 17, 2010

Dr. Witton dismisses more evidence for the existence of giant pterosaurs in the Lower Cretaceous


I really liked my English Literature teachers at school. They were extremely laid back, personable folks who treated us like adults, which is a big deal when you’re 16 years old. They encouraged individuality in our interpretations of books and, indeed, my experience with them had me seriously considering teaching English if this palaeontology lark went nowhere. They even bought us books at the end of our A’ Levels that they thought matched our personalities: I got Joseph Conrad’s Heart of Darkness - make of that what you will.

Unfortunately, they didn’t have the easiest ride when teaching me as I used to wind them up without end. Not, you understand, by drawing inflated phalluses on my exercise book, or by never handing assignments in, talking in class or constantly underachieving: no, I was routinely criticised for making them laugh with my essays. Apparently, nicknaming Hamlet ‘Hammy’ wasn’t standard practise and, so I hear, nine essays out of ten did not compare the cast of Volpone to characters from Only Fools and Horses. Likewise, passages in The Handmaid’s Tale weren’t often compared favourably to lyrics from Eurythmics numbers and, generally speaking, calling The Great Gatsby’s Tom Buchanan a douche wasn’t the done thing. Thing is, none of my teachers had any problems with what I was saying, but the way that I expressed myself was just not on. ‘Don’t write like this’, my teachers told me time and again, ‘your examiners won’t appreciate it’. This confused me as a 16 year old and still does now. Do exam markers have no sense of humour? I’ve yet to meet someone who marks GCSE’s and A’ Levels, but, from this, I imagine they must resemble the enjoyment-hating Blue Meanies from The Yellow Submarine, stamping out positivity with rocket-propelled gloves, clown-controlled explosives and apple-lobbing men in top hats. At least, I hope they do: it’s a much more interesting picture than a bunch of sour-faced miseries sitting in grey office cubicles, angrily scribbling over exam copy books in red pen.

Nowadays, the only scribing I do with intentional dryness is for scientific papers (and even this has been described as too florid by some referees). It produces a strange, sub-schizophrenic feeling when writing and reading it, almost like the ‘Witton’ character cited in other papers isn’t really me: he’s some faceless, professional authority on pterosaurs, someone working in a studious, clean office and certainly not writing papers crashed out on his sofa with repeats of Top Gear on the TV and holes in his socks. But no, these people are one and the same and, to prove it, this post features some suitably dry text I had rejected from a chapter I’m coauthoring on Wealden Supergroup pterosaurs with Dave Martill and Steve Sweetman. For those who don’t know, the Wealden Supergroup is a historically significant series of Lower Cretaceous deposits found across southern England and is one of Europe’s top sites for terrestrial vertebrates of this time. The text evaluates claims that some Wealden pterosaur material represents pterosaurs of gigantic proportions and, because it’s hardly significant enough to warrant its own paper and we discussed other claims for gigantic pterosaurs in the Lower Cretaceous several weeks back, it seems like ideal fodder for the Pterosaur.Net blog. Before it starts, though, it’s worth pointing out that if these and my previous musings on these topics are correct, giant (say, 7 m spans and above) are an exclusively Upper Cretaceous phenomenon. OK? Great. Without further ado, then, I hand you over to my concise, authoritative sounding alter ego, Dr. Witton. If anyone needs me, I’ll be in the lounge watching TV and playing with my feet.

Giant pterosaurs in the Wealden Supergroup?


Martill et al. (1996) and Howse et al. (2001) reported on several bone fragments from the Wessex Formation that allegedly revealed the presence of giant pterosaurs – possibly rivalling the 10 – 11 m wingspans of the largest known forms (Langston 1981) - amongst the Isle of Wight assemblage. The most pertinent of these fragments were a poorly preserved distal humerus (ICWMS 1995.631; 75 mm wide, A and B in the adjacent image [from Martill et al. 1996]) and a fragment of proximal first(?) wing phalanx (ICWMS 1995.629; 53 mm minimum width,C and D in the adjacent image) that, although fragmentary, are the largest articular ends of any pterosaur long bones yet reported from the Wealden.

The identity of these bones as giant pterosaurs is questionable, however. Both Martill et al. (1996) or Howse et al. (2001) report the allegedly giant remains as those of indeterminate pterosaurs, but the distal profile of ICWMS 1995.631 corresponds well with the distal humeri of ornithocheiroids (Hooley 1913; Wellnhofer 1985; Kellner and Tomida 2000) and is almost certainly a member of this clade. Accordingly, greater constraint can be placed on its size than previously realised. ICWMS 1995.631 is 17 per cent wider than the (63 mm) distal width of the Istiodactylus humerus reported by Hooley (1913; BMNH R706) but only 5 per cent wider than the same dimension (71 mm) reported for Anhanguera by Kellner and Tomida (2000; NSM-PV 19892). It is also substantially smaller than that of a large Pteranodon (102 mm; Bennett 2001; YPM 1175). The wingspans of these forms can be relatively well constrained at 5 m in the former cases and between 6 – 7 m for the latter. The transverse dimensions of these bones will not equate to proportional increases in humeral length either as pterosaur long bone articulations increase with positive allometry compared to length (for a good graphic example, compare the 5 and 10 -11 m span Quetzalcoatlus humeri figured by Wellnhofer [1991], p. 141). Thus, ICWMS 1995.631 would be negligably longer than the Istiodactylus and Anhanguera humeri mentioned above, suggesting it too was around 5 m in wingspan. It represents, therefore, a relatively large ornithocheirid but a ‘medium’ sized pterosaur overall.

The size of the individual represented by the possible first wing phalanx ICWMS 1995.629 is harder to determine as the specimen itself is hard to identify. Although the thinness of the bone wall indicates it is a pterodactyloid bone, the specimen lacks any features of note bar the expansion of one end and an oval cross section. Such attributes could apply to several pterosaur long bones: the distal half of the humerus, either end of the radius or ulna or the proximal wing metacarpal but, crucially, do not apply to the proximal phalanx of the wing finger. In at least some pterosaurs, these bones have cross sections that resemble rounded triangles, not ovals (Wellnhofer 1985). The identity of ICWMS 1995.629 as a giant pterosaur is dependent on its identification as a proximal wing phalanx as, if it represents another of the elements listed above, its proportions are unremarkable. With an identity as a proximal wing phalanx doubtful, its status as a pterosaurian giant is also unlikely.

Thus, there is no evidence that the Wealden Supergroup contained pterosaurs of particularly gigantic size. While the 5 m span Wealden forms are much larger than any modern flying animals, their wingspans are quite typical of Lower Cretaceous forms and much smaller than the true giants that would evolve later in the Cretaceous.

References

  • Bennett, S. C. 2001. The osteology and functional morphology of the Late Cretaceous pterosaur Pteranodon. Palaeontographica Abteilung A, 260, 1-153.
  • Hooley, R. W. 1913. On the skeleton of Ornithodesmus latidens; an Ornithosaur from the Wealden Shales of Atherfield (Isle of Wight). Quarterly Journal of the Geological Society, 96, 372-422.
  • Howse, S. C. B., Milner, A. R. and Martill, D. M. 2001. Pterosaurs. In: Martill, D. M. and Naish, D. (eds.), Dinosaurs of the Isle of Wight. Palaeontological Association, Field Guide to Fossils 10, pp. 324-335.
  • Kellner, A. W. A. and Tomida., Y. 2000. Description of a new species of Anhangueridae (Pterodactyloidea) with comments on the pterosaur fauna from the Santana Formation (Aptian -Albian), Northeastern Brazil. National Science Museum, Tokyo, Monographs, 17, 1-135.
  • Langston, W. Jr. 1981. Pterosaurs. Scientific American, 244, 92-102.
  • Martill, D. M., Frey, E., Green, M. and Green, M. E. 1996. Giant pterosaurs from the Lower Cretaceous of the Isle of Wight, UK. Neues Jahrbuch fur Geologie und Paläontologie, Monatshefte, 1996, 672-683.
  • Wellnhofer, P. 1985. Neue pterosaurier aus der Santana-Formation (Apt) der Chapada do Araripe, Brasilien. Palaeontographica. Abteilung A, 187, 105-182.
  • Wellnhofer, P. 1991. The Illustrated Encyclopedia of Pterosaurs. Salamander Books Ltd., London. 192 pp.

Monday, October 11, 2010

Pterosaur books to know and love, part 2: The Pterosaurs from Deep Time


Many, many moons ago, the Heroes of Pterosaur.Net were suggested to provide a reading list for people who just can’t get enough of our leathery-winged chums. Longer-term Pterosaur.Net groupies with good memories may recall that our suggested shortlist was, well, very short with only two notable tomes: Peter Wellnhofer’s 1991 Illustrated Encyclopaedia of Pterosaurs and David Unwin’s The Pterosaurs from Deep Time (2005). You were promised reviews of both: we looked at the Encyclopaedia back in January (seriously, where is 2010 going?) and, today, we’re casting our critical eyes over The Pterosaurs from Deep Time. If it sounds like the pterosaur book for you, however, you’re going to have to go Sherlock to find it: it’s been discontinued for a number of years and only loiters now in second-hand stores. However, Mike from Ottawa informed us last time that he found a cheap copy in an online store that only set him back $10, so you may not have to pay through the nose to obtain one. Question is, of course, do you want to own it in the first place?

The best pterosaur book since the last one
Believe it or not, there have only ever been three popular English books on pterosaurs published: Harry Seeley’s Dragons of the Air (1901 – yes, 1901), Wellnhofer’s Encyclopaedia, and the organ under our spotlight today, The Pterosaurs from Deep Time. The former books set a high benchmark for treatment of their subject matter: Seeley’s book is a classic, a slice of pterosaur history that summarises Seeley’s heretical ideas on pterosaur origins, biology and ecology. Seriously diehard pterosaur aficionados will want a copy but, alas, unless you find a lucky copy in a second hand shop, you’ll have to fork out a lot for it (cheapskates like me, though, can download the entire thing, for free, from here). Wellnhofer’s effort, as discussed previously, remains an essential reference tool for anyone with an interest in flying reptiles and has aged with dignity over the last 20 years. In fact, the only thing that Wellnhofer got wrong with his book was his timing: it was published just before the recent pterosaur research bonanza started (fuelled by spiffing new specimens from Brazil and China) and, therefore, doesn’t report the cohesion of ideas that he may have if he wrote it in 2000, say.

So, when Dave Unwin entered this arena with his book in 2005, he wasn’t exactly swamped with competition. With his main contenders being a dusty, ultra-rare historical tome and an excellent but rather old-fashioned encyclopaedia, he could’ve produced a sloppy, poorly-illustrated mess and still stood a chance of writing the best modern pterosaur book. Thankfully for us, The Pterosaurs from Deep Time continues the trend of its predecessors and is an excellent, informative presentation of modern ideas in pterosaur research. Given the prestige of its author, this isn’t a huge surprise: David Unwin is widely recognised as one of the foremost pterosaur experts in the world. Beginning his career with an assessment of the Victorian taxonomic mess that is the Cambridge Greensand pterosaur assemblage, Unwin has since worked on pterosaurs from all over the world and made significant contributions to research on virtually all aspects of their palaeobiology (including [deep breath]: pterosaur phylogeny, several geographical and taxonomic reviews, details of their flight apparatus, pterosaur respiration, reproduction, terrestrial locomotion and, most recently, bringing the world Darwinopterus). Given that his writing style is also extremely breezy and clear, he's surely one of the most suitable pterosaur palaeontologists around to summarise the current status of pterosaur knowledge. Hence, saying Unwin’s book is ‘the best since the last one’ is not only true by default, but also a considerable complement in saying that Deep Time is a worthy follow-on to Wellnhofer’s Encyclopaedia.


The pterosaur story
Although comparisons between Deep Time and the Encyclopaedia are inevitable, they're not entirely fair because the two books have very different formats. The Encyclopaedia is quite schematic in its layout with clearly defined sections and liberal use of detailed, technical diagrams: it feels far more like a textbook than something you would read from cover to cover. Deep Time, by contrast, is far more prosaic, flowing from chapter to chapter in a continuous way that makes it very easy to read in entirety. It begins with an introduction to pterosaurs and the concepts of fossilisation and geological time before moving onto an overview of pterosaur phylogeny (based on Unwin’s 2003 work), their anatomy, locomotion, reproduction and, finally, an attempt to tell the complete tale of pterosaur evolution. The encompassing approach of this latter chapter is very characteristic of Unwin’s work: many of his technical publication feature discussions of the broader implications for whichever topic is under scrutiny, be it eggshells (Unwin and Deeming 2008) or wing membrane distribution and terrestrial locomotion (Unwin 1999). The story presented in the penultimate chapter of Deep Time seeks to tie all the threads from the prior chapters together, explaining how and why pterosaurs took to the skies, the rise and success of pterodactyloids and their eventual extinction. Beyond this lies a wealth of footnotes and references to keep technical pterosaur buffs happy, along with a list of valid pterosaur species. As may be expected, the information was, at the time of writing, entirely up-to-date and we’re given the full benefit of the first 15 pterosaur bonanza years, including pterosaur brain CT scans to the wealth of soft-tissue data revealed by Brazilian and Chinese fossil Lagerstätten. There is, therefore, a wealth of information and interpretation held in Deep Time and, thanks to Unwin’s frequent quips and asides, it’s as enjoyable to read as it is informative.

We’re treated to glossy, full-colour illustrations for much of the book and, while the sources of many images will be known to those familiar with other pterosaur literature, most diagrams and drawings are well-executed and tie in nicely with the text. The excellent photographs, many of which are of previously unpublished details of well-known specimens or entirely new finds, are worthy of mention as are the superb pterosaur paintings by Todd Marshall that are dotted throughout the book (see image, above, of a Marshall Quetzalcoatlus, along with the Sordes on the book cover at the top of this post). I have a soft-spot for Marshall’s work: his animals and environments look refreshingly imperfect, a bit like they’ve been left outside in the wind and rain for some time. Plus, his style is one of the most striking and recognisable among the modern crop of palaeoartists. His punky, scruffy pterosaurs are no exception, and the depth he gives to his environments creates the impression of a broader world beyond the confines of the canvas. Happily, his pterosaur anatomy and postures aren’t too bad either, making his images a handy source of modern pterosaur restorations.

But…
So it’s praise, praise, praise, for Deep Time, then, but it’s not all good. For one thing, while most of the figures are absolutely spiffing, a few are a bit shaky with ugly, blocky lines, flat colours and poorly-defined details. This never becomes so much of a problem that you cannot see what the figure represents and there are only a handful of instances in the entire book, but the difference in quality between some illustrations is marked. The largest issue I have with Deep Time, however, is that sometimes the reader is given the impression that we know more about pterosaurs than we actually do. Take, for instance, Unwin’s arguments that a lack of pterosaur footprints prior to the mid-Jurassic is indicative of poor terrestrial abilities in non-pterodactyloid pterosaurs: is the record of pterosaur footprints really that complete that we can conclude this? I mean, how many trackways do we have of arboreal protosaurs or small, lithe dinosauriforms? Does that mean that they were clumsy, sluggish terrestrial animals, too? Though I can partially see Unwin's point on this one, I'm skeptical of using negative evidence in such a way, particularly with groups like pterosaurs with particularly patchy fossil records. Likewise, the suggestion that lonchodectids were Cretaceous pterosaur generalists seems a little bit of a stretch given that virtually no-one knows what they were really like and their record is very limited indeed.


On a similar note, the digital modelling of pterosaur terrestrial locomotion – the ‘Roborhamphus’ and ‘Robodactylus’ models crafted and worked on with Don Henderson (see Don's animation above, stolen from here) – is presented as accepted fact when, if I’m not mistaken, this work has only been published in a few abstracts (Unwin and Henderson 1999; Henderson and Unwin 1999) and not actually peer reviewed (please correct me if I’m wrong, though). Given that these models are somewhat at odds with other interpretations of pterosaur anatomy (e.g. laterally projecting hindlimbs in the Rhamphorhynchus model [contra. Padian 1983; Bennett 1997] and inflexible wrists in the pterodactyloid variant [contra. Bennett 2001; Wilkinson 2008; plus lots of pterosaur specimens with articulated, flexed wrists orientating depressing the wing metacarpal at least 40 degrees from the radius/ulna]), it may have been nice if a few more caveats about this work had been put in somewhere. Happily, this section of the book is unusual in not citing other, alternative interpretations and, in most instances, alternative hypotheses are mentioned and discussed.

Still, nothing’s perfect
These are relatively minor quibbles when the overall quality of the book is considered, though, and issues like those mentioned above are too rare top be major failings. In sum, then, even if you already own Wellnhofer’s Encyclopaedia, Deep Time is an essential purpose for the more up-to-date information it contains and, if you’re new to pterosaurs, it’s hard to imagine a better introduction. The fact that I've recommended this book to so many students and other pterosaurphiles is further testament to its quality and, frankly, it leaves a hard act to follow for the next guy in line writing a popular pterosaur book. Wait a second...

References

  • Bennet, S. C. 1997. The arboreal leaping theory of the origin of pterosaur flight. Historical Biology, 12, 265-290.
  • Bennett, S. C. 2001. The osteology and functional morphology of the Late Cretaceous pterosaur Pteranodon. Palaeontographica Abteilung A, 260, 1-153.
  • Henderson, D. and Unwin, D. M. 1999. Mathematical and computational model of a walking pterosaur. Journal of Vertebrate Paleontology, 19, 50A.
  • Padian, K. 1983. A functional analysis of flying and walking in pterosaurs. Palaeobiology, 9, 218-239.
  • Seeley, H. G. 1901. Dragons of the air. Meuthuen and Co., London, United Kingdom, 239 pp.
  • Unwin, D. M. 1999. Pterosaurs: back to the traditional model? Trends in Ecology and Evolution, 14, 263-268.
  • Unwin, D. M. 2003. On the phylogeny and evolutionary history of pterosaurs. In: Buffetaut, E. and Mazin, J. M. (eds.) Evolution and Palaeobiology of Pterosaurs, Geological Society Special Publication, 217, 139-190.
  • Unwin, D. M. 2005. The Pterosaurs from Deep Time. Pi Press, New York, 347 pp.
  • Unwin, D. M. and Deeming, D.C. 2008. Pterosaur eggshell structure and its implications for pterosaur reproductive biology. Zitteliana, B28, 199-207.
  • Unwin, D. M. and Henderson, D. 1999. Testing the terrestrial ability of pterosaurs with computer-based methods. Journal of Vertebrate Paleonotology, 19, 81A.
  • Wellnhofer, P. 1991. The Illustrated Encyclopedia of Pterosaurs. Salamander Books Ltd., London. 192 pp.
  • Wilkinson, M. T. 2008. Three dimensional geometry of a pterosaur wing skeleton, and its implications for aerial and terrestrial locomotion. Zoological Journal of Linnaean Society, 154, 27-69.

Thursday, October 7, 2010

If you must procrastinate, procrastinate in pink


This October sees the fine fellows of Art Evolved hosting a rather unique palaeoart charity event for the Canadian Cancer Society. Coinciding with Breast Cancer Awareness Month, they're donating $1 to the CCS for every illustration of a pink dinosaur (and hopefully other prehistoric beasties) sent to their site. Because the moral backbone of Pterosaur.Net is strong enough to build a bridge with, we couldn't resist doing our bit by adding some membraney-goodness to said event. Alas, time is short and the best I could manage was mere colour tweaking on this Ornithocheirus/Criorhynchus (there's confusion over just what these animals are, but we don't have time to go into that now): hopefully others can do better.

Head over to Art Evolved to find details on how to submit your own flamboyantly coloured extinct saurian and, if you need inspiration to get some pink paint out of the cupboard, crank your speakers up and stick this on. Coincidentally, my choice of red neckgear today is entirely identical to that seen in this video. Not sure what that says about me, but there you go. Anyway, stop reading this and get pinking!

Saturday, October 2, 2010

In which the Pterosaur.net blog gets seriously self involved

Ok so it's another re-post from my blog but one that is doubly relevant to pterosaurs. First of all, it contains pterosaur artwork of the highest quality and secondly, it's me interviewing John Conway about his art. So really it's kinda pterosaur.net squared. On an utterly unrelated note, but potentially of interest, if you are in anyway shape or form involved or interested in palaeontology then check out this years Palaeo Project Challenge over on Andy Farke's blog.

Right, onto the meat of the post.



These palaeoart interviews (see here for Luis Rey, Bob Nicholls, Brett BoothJulia Molnar) have been very popular and I'm enjoying finding out how my friends and colleagues see their own work and that of others and with that, drumroll, it's the turn of John Conway. John has a big hand in Pterosaur.net and a generally huge web presence (most recently has seen the launch of his Ontograph Studios) when it comes to palaeo reconstructions but while he might have a lot of words and images online, until now he's not yet succumbed to the rigours of a Musings art interview. Take it away John (as ever, all art wrok is John's intellectual property):

Friday, September 17, 2010

On a wing membrane and an ankle attachment.

Regular pterophiles will realise that this is just a direct re-post from my own blog. However, the more dedicated pterosaur blog hound might not have seen this, so here's the post in all it's glory.

Proof, if it were needed, that the Pterosaur.net team do actually work on pterosaurs and not just blab endlessly about them comes from todays new paper featureing Ross Elgin, myself and Dino Frey. Once more, this is an odd time to talk about it since what has actually turned up are the uncorrected proofs, but it is out there and being read, so now is the time to talk about it. (You can download and read it here, and a very old post of mine here might be a good primer if you don't know your pterosaur wings too well).

Friday, September 10, 2010

Euparkeria be damned: it's ROFLopterosauria


I've tried to be good. No blogging for a bit while I catch up with work/job applications/dismantling the oven to clean it properly, but Ashley Fragomeni, aka Paleochick, has just gone and blown the whole thing. Her antics over at The Paleochick's Digs mean that, instead of finishing the Euparkeria skeletal reconstruction I need for my book, I'm now telling you about her ROFLopterosauria series, an collision of my pterosaur palaeoart and erudite observations into pterosaur palaeobiology. The latest one was just too funny to ignore, so here we are. On the internet. Blogging. Now my book won't be finished on time, I won't get paid, I won't make the rent and I'll be forced to sell my kidneys (both of them) and other parts of my body to make ends meet. Thanks a lot, Dusty.

We're promised a new bit of ROFLopterosauria every day or so for the next few days, so be sure to head back to the Paleochick's Digs over the next week to see more. The image above has nothing to do with anything you've just read, but shows Peter Wellnhofer's Rhamphorhynchus mobile on display in the Palaeontology Museum, Munich. We can't, after all, have a dull-looking blog post, can we?

Saturday, September 4, 2010

Gorgonophilia, Star Trek and how they relate to giant pterosaurs in the Lower Cretaceous


I was very happy to find that my airline had provided me with my own little TV screen and a selection of movies for my flight back from Flugsaurier 2010. With eight hours to kill, this was welcome news and, as soon as we were away and provided with those annoying little earbud headphones that never really fit your ears properly, I was off to Movieland. First up: the remake of Clash of the Titans, a flick that I’d not heard great things about but promised nice visuals, minimal cerebral action and plenty of nice CG creatures. The reviews I’d read were spot on: clichéd characters, dialogue so wooden it could serve as a useful boat oar and numerous clumsy attempts to cash in on the 3D bandwagon kicked off by Avatar. Still, it did feature a nicely rendered Pegasus, giant scorpion caravans and Medusa, a snake-woman hybrid that I found worryingly attractive. Most concerning is that it wasn’t just the top half that made for the most pleasant viewing (which would be understandable, given that her appearance was based on model Natalia Vodianova): there’s clearly a part of my psyche, unrecognised until a week or so ago, that really digs the thought of scantily-clad snakewomen sliding and coiling around their room and constricting visitors to their chambers. Imagine how touchy-feely that would be: you’d not mind having a late breakfast with that. Man, that' d be a night to remember. Just think of the... oh… wait a second. Oh yeah: pterosaurs. Blog post. Decency. No mythophilic filth. Got it.

Next up: last year's Star Trek reboot. Now, I’ve never seen eye-to-eye with Star Trek. I was once a massive fan of Star Wars, but Trek? No. Just couldn’t get into it. Lots of talking; uniforms that looked a bit like the pyjamas I used to wear; big, lumbering spaceships that fire weedy looking weapons; aliens that look just like people with pies glued to their foreheads and, most importantly, a distinct lack of Han Solo. Bottom line: I just found it a bit dull so, when I heard the whole thing was being rebooted I wasn’t terribly excited by the idea. Still, the reviews were pretty good so I thought I’d give it a whirl. I did, after all, have several hours of flight time to kill.

You know what? It was great. It was exciting. It had proper aliens and gripping, tense action scenes. It had Simon Pegg. It wasn’t clean cut: there was even a bit of proper, honest-to-goodness swearing. I was totally surprised and, while I’m unlikely to change my opinion on the other entries in the franchise, I’ll certainly give the 2012 Trek sequel a spin. I may even pay to see it at the cinema. You know: with my own money and everything.

And the new Star Trek is just like pterosaur specimen n. 12701a of the Ligabue collection


Seriously. For the uninitiated, n. 12701a is a tiny distal fragment of a pterosaur wing phalanx one from the Santana Formation of Brazil (described by Dalla Vecchia and Ligabue 1993; n. 12701a shown in adjacent line drawing). When I say fragment, I’m not kidding: it’s really is one of the most unremarkable, dull and uninteresting scraps of pterosaur fossil ever published on and, like the old Star Trek, it’s the sort of thing that we should only really be bothered about when there’s no reruns of The Simpsons on the telly. In fact, probably the only thing stopping n. 12701a from being totally forgotten about is its size: for a distal fragment of a wing phalanx, it’s huge. At 75 mm across, Dalla Vecchia and Ligabue reconstructed the length of the complete phalanx as 850 mm (based on ornithiocheiroids such as Pteranodon and Santanadactylus), a dimension almost twice the size of comparable elements from 4 -5 m span ornithocheirids. Using complete ornithocheirid wings as a guide, the authors then went on to suggest that tiny-little-fragment n. 12701a represents an animal with a whopping 8 – 9 m wingspan.

Now, in a world where the largest pterosaurs span something like 10 m, the predicted wingspan of n. 12701 isn’t really a big deal. What is, however, is its age: aside from this and some other problematic remains from Britain*, there are no accounts of giant pterosaurs in the Lower Cretaceous. Hence, n. 12701 suggests that sizes pretty-near comparable with the largest pterosaurs of all were achieved tens of millions of years before Pteranodon and the giant azhdarchids turn up. All of a sudden, then, that chunk of pterosaur is starting to look far less pre-2009 Star Trek-esque and far more akin to the 2009 reboot: it's exciting, interesting and, being the lone wolf for giant pterosaurs of this time, a touch edgy. Indeed, people have probably been getting excited about n. 12701a for some time: I wouldn’t be surprised if it influenced the decision to portray Ornithocheirus with a 10 m span in Walking with Dinosaurs, for instance (see image at the top of the post, from here).

*There is one additional claim for giant pterosaurs in the Lower Cretaceous based on very, very scrappy material from the Isle of Wight, UK (Martill et al. 1996). We don’t have time to go into the details here, but there’s good reason to think that these remains were not from giant animals. The rationale for this has been written up by myself, Dave Martill and Steve Sweetman and should be published next year.

Alas, n. 12701a may not be quite as New Trek as we all thought. To be honest, I’ve never been fully convinced that it demonstrated giant pterosaurs were present in the Lower Cretaceous: it’s just so scrappy that drawing any conclusions about its overall size seems extremely spurious. A little bit of further investigation reveals why this gut feeling may be right.

That was then: this is now
To begin with, there no way that n. 12701a can be allocated to any pterosaur group: it’s just too scrappy and undiagnostic (Dalla Vecchia and Ligabue stated this themselves, but it bears reiterating here because it will prove important later). It is probably sensible to suspect it represents a group known from the Santana Formation, meaning it could either represent an ornithocheirid or an azhdarchoid. Now, in 1993, the Santana Formation was mainly known for its ornithocheirids (e.g. Unwin 1988) and azhdarchoids were relatively new kids on the block (Kellner and Campos 1988; Kellner 1989). Since then, however, we’ve found much more azhdarchoid material including up to three new species (Kellner and Campos 1994, 2002; Witton 2009), complete skeletons (Kellner and Hasagawa 1993) and buckets of incomplete specimens that are sitting in museum stores. This suggests that azhdarchoids were a far more speciose and abundant component of the Santana Formation pterosaur assemblage than could be predicted in the early ‘90s, then, and this is means that we need to strongly consider that n. 12701a may have azhdarchoid affinities.


This is potentially quite a big deal because azhdarchoids and ornithocheirids have very different wing constructions (see diagram of pterodactyloid wing configurations, above. The top image shows the ornithocheirid wingplan; middle image, the azhdarchid wingplan; bottom, tapejarid wingplan. From Witton [2007]). The wing phalanges of ornithocheirids are far more proportionate along the length of the wing finger, decreasing in size distally but only by comparatively small measures (e.g. Wellnhofer 1985). Azhdarchoids, by contrast, have massive first phalanges in their wing fingers (occupying over 40 per cent of the total finger length) but then drastically reduced second, third and fourth elements (Unwin 2003; Kellner 2003). What’s more, the diameters of the distal wing phalanges decrease in size dramatically across the azhdarchoid wing: that of the first is proportionally enormous compared to the rest. What this is leading up to, then, is that an azhdarchoid could have a massive first wing phalanx like that represented by n. 12701a without being a pterosaur giant. In fact, scaling an azhdarchoid wing using the 850 mm-long first phalanx length predicted by Dalla Vecchia and Ligabue gives a single wing length of just 3 m, and, therefore, a total wingspan of 6 m. That’s big, sure, but hardly gigantic for a pterosaur. Plus, this estimate supposes that the 850 mm length reconstuction of n 12701a is appropriate: would the same estimate be generated if it were based on a non-ornithocheirid pterosaur?


The plot thickens further when we consider that large azhdarchoids are already known from the same locality as n. 12701a. The Santana Formation thalassodromid Thalassodromeus, in particular, is a huge animal with a jaw approaching a metre in length (see image, above, of the author posing in a most embarrassing fashion with a full-size Thalassodromeus bust). Estimating the wingspan for this animal is difficult as no postcranial material is known, but its skull proportions suggest a 5 m span (Kellner and Campos 2002). Given how little data we have regarding the proportions between neoazhdarchian skulls and wingspans, it may not be entirely crazy to suppose a 6 m wingspan, either. Along with everything else, then, there are pterosaurs in the Santana Formation that would be a good size match for n. 12701a if it were, indeed, an azhdarchoid.

So, Lower Cretaceous giant pterosaurs, then?
None of this delivers a death-blow to the idea of giant pterosaurs existing in the Lower Cretaceous of course, but it certainly suggests that there is an equally, if not more, parsimonious interpretation of n. 12701a than it being the sole remnant of a giant ornithocheirid species. If nothing else, ornithocheirids are among the best represented of all pterosaurs and, in our extensive sampling of them, there’s no other evidence for such enormous animals (at least, none that I’m aware of). Considering n. 12701a as an azhdarchoid is a far more believable interpretation: it scales to a wingspan that we know azhdarchoids achieved, we would expect its overly large proportions in an azhdarchoid wing and, indeed, there are even comparably sized azhdarchoids in the same deposit. As such, while I’m not going to rule out the evolution of giant pterosaurs in the Lower Cretaceous entirely, I think we need far more evidence that we currently have to consider their existence likely.

And that, folks, is it for now. It’s Saturday night, so I’ll take my tale of how n. 12701a went from being boring to being really exciting and then boring again to the pub. Hey, you never know: there may be some women down there that, from the waist down, resemble rattlesnakes. You never know. I need to get ready. Clean, ironed shirt? Check. Wallet, house keys and phone? Check. Reflective shield and anti-venom? Check. Right, toodles.

References

  • Dalla Vecchia, F. M. and Ligabue, G. 1993. On the presence of a giant pterosaur in the Lower Cretaceous (Aptian) of Chapada fo Arariple (northeastern Brazil). Bollettino della Scoietá Paleontologica Italiana, 32, 131-136.
  • Kellner, A. W. A. 1989. A new edentate pterosaur of the Lower Cretaceous of the Araripe Basin, Northeast Brazil. Anais da Academia Brasileira de Ciências, 61, 439-446.
  • Kellner, A. W. A. 2003. Pterosaur phylogeny and comments on the evolutionary history of the group. In: Buffetaut, E. and Mazin, J. M. (eds.) Evolution and Palaeobiology of Pterosaurs, Geological Society Special Publication, 217, 105-137.
  • Kellner, A. W. A. and Campos, D. A. 1988. Sobre um novo pterossauro com crista sagital da Bracia do Araripe, Cretáceo Inferior do Nordeste do Brasil. Anais da Academia Brasileira, Ciências, 60, 459-469.
  • Kellner, A. W. A. and Campos, D. A. 1994. A new species of Tupuxuara (Pterosauria, Tapejaridae) from the Early Cretaceous of Brazil. Anais da Academia Brasileira, Ciências, 66, 467–473.
  • 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.
  • Kellner, A. W. A. and Hasagawa, Y. 1993. Postcranial skeleton of Tupuxuara (Pterosauria, Pterodactyloidea, Tapejaridae) from the Lower Cretaceous of Brazil. Journal of Vertebrate Paleontology, 13, 44A.
  • Martill, D. M., Frey, E., Green, M. and Green, M. E. 1996. Giant pterosaurs from the Lower Cretaceous of the Isle of Wight, UK. Neues Jahrbuch fur Geologie und Paläontologie, Monatshefte, 1996, 672-683.
  • Unwin, D. 1988. New pterosaurs from Brazil. Nature, 332, 398-399.
  • Unwin, D. M. 2003. On the phylogeny and evolutionary history of pterosaurs. In: Buffetaut, E. and Mazin, J. M. (eds.) Evolution and Palaeobiology of Pterosaurs, Geological Society Special Publication, 217, 139-190.
  • Wellnhofer, P. 1985. Neue pterosaurier aus der Santana-Formation (Apt) der Chapada do Araripe, Brasilien. Palaeontographica. Abteilung A, 187, 105-182.
  • Witton, M. P. 2007. Titans of the skies: azhdarchid pterosaurs. Geology Today, 23, 33-38.
  • Witton, M. P. 2009. A new species of Tupuxuara (Thalassodromidae, Azhdarchoidea) from the Lower Cretaceous Santana Formation of Brazil, with a note on the nomenclature of Thalassodromidae. Cretaceous Research, 30, 1293-1300.

Sunday, August 29, 2010

Big news at Flickr


Dead quick post this one. In fact, it's simply instruction to point your browser here. There's not only some interesting pterosaury information on offer, but also a big announcement. Well, big for me, anyway.

The adjacent Pteranodon image, by the way, has nothing to do with anything mentioned here or there: he's just jazzing up the post a bit.

Saturday, August 28, 2010

The unexpected, dreaded link between Flugsaurier 2010 and linen blazers


By jingo, I’ve just realised I’m worryingly close to being a yuppie. All the signs are there: I’m sitting in Costa coffee in Portsmouth’s Gunwharf Quays, a trendy waterfront complex of designer stores and chain restaurants. There’s an enormous cappuccino steaming away alongside my laptop, an iPod pouring music into my ears and I’ve inadvertently dressed entirely in designer clothes. Crap: I’ve even got a linen blazer draped over the chair opposite. I’m a haircut and an IKEA catalogue away from a leading role in a J. J. Abrams production. When did this happen? What happened to the slightly-alternative left-liberal arty type that I used to be? When did I suddenly become so… so… faux professional? Terms like ‘incentivise’ and ‘core competencies’ could now pass my lips and no-one would bat an eyelid. I feel so… middle management.

Best get to the bottom of this while I finish this mighty caffeinated beverage. If I can identify when this young professionalism started creeping up on me, I may be able to do something about it. It certainly wasn’t last night. No, that wasn’t very professional behaviour at all. It wasn’t my holiday in China: it’s hard to look professional when climate and hiking conspire to make you sweat more than an excited, overweight trekkie at his first Star Trek convention. But wait: just before that, there was the 2010 Flugsaurier International Symposium on Pterosaurs, held in Beijing at the start of August. Hmm… dozens of pterosaur experts from all over the world presenting their latest research, specimen viewings, museum visits and field excursions to fossiliferous outcrops of the Jehol Group? Attending that would give any wannabe pterosaur researcher delusions of professionalism: that must be it. Let’s investigate further.

Shiny new things


Flugsaurier 2010 (the particularly handsome, well-designed logo of which greeted you at the start of the post) featured talks and posters from dozens of pterosaur experts on virtually every research avenue of our leathery-winged chums. The talks were excellent and, it must be said, there was a surprising sense of intellectual cohesion. Pterosaur researchers are renowned for holding quite polar views on numerous topics but, at Flugsaurier 2010, there was a good sense that we’re starting to sing from similar song sheets. We don’t have time to mention every talk and poster of the conference (39 abstracts were submitted in total), but notable highlights included conference organiser Lü Junchang’s overview of Chinese pterosaurs, a talk that served to remind us how much China has contributed to pterosaur research since the discovery of the first Chinese pterosaur material in 1935. Fellow Pterosaur.Net host Dave Hone presented a new specimen of the anurognathid Dendorhynchoides that – get this – has a relatively long tail. The length of the tail in this animal has been controversial since its description (Ji and Ji 1998; drawing of the holotype, above, from this publication) thanks to some fabrication in the caudal region by its discoverers (Unwin et al. 2000). However, it turns out that the relatively long tail of the holotype was only partially restored and Dendorhynchoides did, indeed, have a longish tail. Dave continued to point out that there’s a wealth of phylogenetic potential in tail length: we just have to figure out a way to code it in a meaningful way. (You can see Dave’s comments on the meeting, incidentally, at this post at the Musings)

Further new discoveries were presented by Fabio Dalla Vecchia with a new, as yet unnamed, Triassic pterosaur from northern Italy. The affinities of this animal aren’t yet clear, though it appears to have some Raeticodactylus-like features. My fellow University of Portsmouth pterosaur worker, PhD student Steve Vidovic, presented his work on pterosaur tooth microstructure and revealed an unusual tooth tissue, neither dentine, cementum or enamel, comprising much of the external surface of pterosaur teeth. A movement is underway amongst certain pterosaur workers to christen this the ‘Vidovic Layer’ in a special avant-garde dancing and fireworks ceremony: please drop us a line if you’ve chorus line or pyrotechnics experience.

Helmut ‘UV wizard’ Tischlinger once again dazzled audiences with a display of new Solnhofen pterosaur specimens that, under UV light, were seen to have ridiculously-proportioned headcrests and hitherto unseen details of wing membrane histology. Worryingly for pterosaur palaeoartists, the size of pterosaur headcrests seems to be increasingly difficult to predict based on skull osteology alone and we may be painting virtually all our pterosaurs with vastly undersize headgear. Sticking with Solnhofen-esque pterosaurs, it was personally gratifying to see Chris Bennett’s poster on the taxonomy of Cycnorhamphus state that the Painten Pelican, a strange, isolated skull from Solnhofen deposits, should be referred to Cycnorhamphus as predicted on these very pages. Chris went on further to suggest that there is only one valid species of Cycnorhamphus, C. suevicus.

Dirty fakes and dissolving trees


Perhaps the most dramatic taxonomic revelation, though, came with the presentation of further preparation work on Cearadactylus atrox (line drawing of the holotype, above, from Unwin 2002), a mostly-complete skull from the Brazilian Santana Formation with unusual dentition and jaw structure (Leonardii and Borgomanero 1983, 1985). Previous views of the partially prepared specimen showed a very ornithocheirid-like cranial region but bizarre, stepped jaw tips with large, somewhat procumbent fangs. Cearadactylus has been classically difficult to place and has been housed amongst ornithiocheiroids (e.g. Dalla Vecchia 1993; Kellner and Tomida 2000) and ctenochasmatoids (Unwin 2002). With additional prep, however, Juliana Sayão was able to reveal that an ornithocheirid affinity was correct and, moreover, all the unusual features of the jaw tip are faked. The stepped nature of the jaw tips arose from the anterior skull and mandible having been broken off and reattached upside-down, while the large fangs were fabricated by imaginative fossil collectors or dealers. Actually, fossil fakery was something of a running theme in the conference: along with the doctored Dendorhynchoides discussed above, several faked pterosaur fossils were seen on display in the museum in Chaoyang Bird Fossil National Geopark and, in the privacy of Dave Hone’s office, we were shown a fantastic complete azhdarchoid-like pterosaur with an entirely fabricated head. The Cearadactylus fiasco is yet another demonstration that distinguishing genuinely unusual vertebrate fossils from those elaborated by dealers can be difficult. In my limited experience of dealing with such things, I reckon we have a good idea of what to expect in most fossil vertebrates so, if a feature looks totally, totally out-of-keeping with everything else we’ve ever seen, there’s the strong possibility that it’s been ‘improved’. Full preparation and investigation with things like UV light are probably the best way to detect potential fakeries but, even then, well-done fabrication can be difficult to detect.

In other talks, the phylogenetic influence of Darwinopterus was discussed by Dave Unwin. Dave plugged everyone’s favourite transitional pterosaur into two of the latest Big Pterosaur Phylogenies – that of Alex Kellner and his own - to see how it would affect tree topology. While Unwin’s own tree remained almost entirely consistent with previous incarnations, Alex’s didn’t fare quite so well and even well-supported groups like Pterodactyloidea collapsed into a polytomy with basal forms. Alex was, unfortunately, unavailable for comment due to being called back to Brazil early in the conference. Further cladistic acrobatics were performed by Chris Bennett with a test for homoplasy amongst predicted pterosaur relatives. Chirs found that characters of the hindlimb associated with cursoriality were likely to have developed convergently with other archosaurs, casting further mist over pterosaur origins.

Play that funky morphy, white boy
Pterosaur functional morphology was discussed at great length in several talks, and flight seemed to be on the topic of the moment. Colin Palmer told us of his physical and digital modelling of pterosaur wing sections and the aerodynamic effects felt across the wing. Mike Habib and I delivered back-to-back talks regarding the flight of giant pterosaurs: following several claims that large pterosaurs may have been flightless (Sato et al. 2009; Henderson 2010), we outlined several flaws in these predictions and that there’s actually very compelling evidence that even the largest pterosaurs could fly. Mike went on to say that, when they did, things like giant azhdarchids went like dynamite: in short, these were animals that could happily continent hop without working up a sweat. Mike and I have a paper accepted for publication on this that should see the light of day soon (at least, it will when I stop writing blog posts and get on with addressing our referee’s comments).


Mike returned to the stage to present his work with Jim Cunningham on water-launching pterosaurs. Pterosaur.Net readers will no-doubt be familiar with the concept of pterosaurian quadrupedal launches by now (see image, above, of Pteranodon mid-launch) and, by gum, it seems to work on water, too. I will say no more because a Mike and Jim have a paper on water launches in the works and, frankly, it’s so cool that I don’t want to steal any more of their thunder than I’ve already stolen. There will be some exceptional pictures being drawn of this stuff, though: hopefully Mike and Jim will get their work out soon.

Odds and ends
Two odds-and-sods presentations were also given: I presented new observations on giant azhdarchid remains that suggest they weren’t as big as we all thought and, changing key slightly half-way through my talk, then went on to discuss Quetzagate, or whatever you want to call the political and taxonomic debacle surrounding Quetzalcoatlus northropi (which, of course, you know all about because you’ve read this). Interestingly, this story was not as well known as I perceived it to be and, frankly, I’m wondering if it may warrant a more formal write up.


A less scandalous topic was covered by John Conway in the closing presentation where John discussed why pterosaur palaeoart – sorry – palaeontography – would benefit from a far more scientific approach. He’s dead right: pterosaurs are frequently portrayed with entirely incorrect proportions, muscle construction and unlikely colour schemes. Unfortunately, I’m amongst the guilty on this but I agree entirely with John: while we will remain shooting in the dark on most issues when reconstructing the life appearance of extinct animals, there are definitely some parts we can be ‘correct’ about (such as size and proportions) and others where we can at least aim for a likely ballpark (colour, behaviour). You can see the Anhanguera artwork that John used as his case study above, and further discussion of these points will feature, at some point, in these halls.

Once we all stopped yammering on


As with Munich before it, a portion of the conference was dedicated to specimen viewing. The new scaphognathine Fenhuangopterus, material referred to Darwinopterus, the chaoyangopterid Shenzhoupterus and a cast of the most complete and articulated large pterosaur I’ve ever seen - Zhenyuanopterus (above, with Dave Hone's cranium for scale) – were on offer. Poster displays took place in the same room but, in a silly move, I got too excited with Shenzhoupterus and didn’t get a proper look at them all. D’oh.

Field trips to outcrops of the Tiaojishan, Juifotang and Yixian Formations followed our time in Beijing, along with visits to several museums with extensive collections of Jehol material. As usual, dinosaurs were given pride of place in these institutions but, happily, other aspects of the Jehol biota were also given plenty of breathing space too.


Steve Vidovic and myself also made trips to the IVPP and Beijing Museum of Natural History: whilst the specimens were nice (and the fossil mammals were pretty incredible), both museums were let down by their woeful, woeful models of prehistoric beasties (image, above, of Beijing MNH Tyrannosaurus and Velociraptor. No, this isn't a joke). Whilst these were kept to a minimum in the IVPP, the Beijing MNHM has dedicated room after room to these travesties and, walking through them, they gave off no sense of wonder or scientific credibility: they were, frankly, a waste of space and money. To a certain extent, the same could be said of the wobbly animatronic dinosaurs littering the Chaoyang Bird Fossil National Geopark, models that are already showing drastic wear and tear after only a few years of operation. They all reminded me of comments made by Matt Wedel years ago concerning museums trying to be theme parks: gee-whizz displays and wobbly mechanised dinosaurs often only cheapen what could be a far more educational and interesting experience if museum developers only trusted public intellect a little more. After all, museum goers are intelligent enough to be interested in museum collections for what they are, not just because it’s associated with a squeaky Tyrannosaurus model that slowly moves it’s head from side-to-side and plays noises recorded from Jurassic Park. This is, of course, a whole issue in itself that I won’t elaborate on any further here, but museum directors take note: give your punters some credit!

And that was that
So, yes, that was Flugsaurier 2010. There are, of course, loads more things I could talk about and apologies to those who contributed and didn’t get a mention here. Thanks to the conference organisers, and particularly Lü Junchang, for putting the whole show together and keeping things running smoothly. Additional thanks go to all my friends and colleagues who made the experience such an enjoyable one, even if you did leave me with an inflated sense of professionalism. Now, with that coffee being long-finished (I’ve got the jittery hands of a high-end caffeine achiever to prove it) and designer threads suffocating my anti-commercialist, liberal attitudes, I must away to cleanse myself of yuppiedom before it's too late. If I'm not careful, I may become respectable. Holy Christmas: I may even grow up. Quick: where’s that linen jacket? I've got a date with that garment and some matches.

UPDATE: 29/08/10
Silly me: I forgot to mention that the conference abstracts are available for viewing here. Navigating your way around them, however, isn't terribly easy unless you can read Chinese. One final thing: Dave Hone had the adjacent image taken of Pterosaur.Net contributors in front of a very, very distant stretch of the Great Wall and, to put some faces to names, I thought I'd post it here. Plus, spreading our desperately handsome features as far as possible is basically a public service and bound to improve the moods of most people, so enjoy. (From left to right: John Conway, your host, Dave Hone, Mike Habib and Helmut Tischlinger)


References

  • Dalla Vecchia, F. M. 1993. Cearadactylus? ligabuei nov. sp., a new early Cretaceous (Aptian) pterosaur from Chapada do Araripe (Northeatern Brazil). Bollettino della Societá Paleontologica Italiana, 32, 401-409.
  • Henderson, D. M. 2010. Pterosaur body mass estimates from three-dimensional mathematical slicing. Journal of Vertebrate Paleontology, 30, 768-785.
  • Kellner, A. W. A. and Tomida., Y. 2000. Description of a new species of Anhangueridae (Pterodactyloidea) with comments on the pterosaur fauna from the Santana Formation (Aptian -Albian), Northeastern Brazil. National Science Museum, Tokyo, Monographs, 17, 1-135.
  • Ji, S. A. and Ji, Q. 1998. A new fossil pterosaur (Rhamphorhynchoidea) from Liaoning. Jiangsu Geology; 22, 199-206.
  • Leonardi, G. and Borgomanero, G. 1983. Cearadactylus atrox, nov. gen. nov. sp.; novo Pterosauria (Pterodactyloidea) da Chapada do Araripe, Ceará, Brasil. Congresso Brasileiro de Paleontologia, resumos, 17.
  • Leonardi, G. and Borgomanero, G. 1985. Cearadactylus atrox, nov. gen. nov. sp.; novo Pterosauria (Pterodactyloidea) da Chapada do Araripe, Ceará, Brasil. Coletânea de Trabalhos Paleontológicos, Série Geologica, Brasilia, 75-80.
  • Sato, K., Sakamoto, K., Watanuki, Y., Takahashi, A., Katsumata, N., Bost, C., and Weimerskirch, H. 2009. Scaling of soaring seabirds and implications for flight abilities of giant pterosaurs. PLoS ONE, 4, e5400.
  • Unwin, D. M. 2002. On the systematic relationships of Cearadactylus atrox, an enigmatic Early Cretaceous pterosaur from the Santana Formation of Brazil. Mitteilungen Museum für Naturkunde Berlin, Geowissenschaftlichen, 5, 239-263.
  • Unwin, D. M., Lü, J. and Bakhurina, N. N. 2000. On the systematic and stratigraphic significance of pterosaurs from the Lower Cretaceous Yixian Formation (Jehol Group) of Liaoning, China. Mitteilungen aus dem Museum für Naturkunde Berlin, Geowissenschaftliche Reihe, 3, 181-206.

Friday, June 25, 2010

The London Pterosaur ExTrAvAgAnZa!!!1!! in full glory


This is a hard post to write. It may be the big latte I’ve just drunk or possibly a sugar low, but there’s a genuine buzz about my fingers as I type this. In short, not too far away from the little café I’m perched in now sits an enormous pterosaur exhibition that the University of Portsmouth amigos David Martill, Bob Loveridge, an army of volunteers and I put together over the last year and a half. It’s been up for several days on London’s Southbank after being installed through the night of Sunday the 20th of June (and I mean through the night: we literally didn’t sleep for 2 days) and will remain there for another week or so. We'll be taking it all away with another all-nighter on the 5th of July. Having a huge display that you personally constructed - and based on your own PhD work - on the Southbank is a little bit exciting, and the fact that I got to meet Princess Anne, attend a Royal Society Convocation (attended by numerous Royals, including Queenie herself) and have numerous people wanting to shake my hand on a job well done while standing around our work is pretty durned good.

Anyway, enough gushing: below is a little taster of what we’ve got in store for Londoners over the next week and a half. You can see the final of our BBC videos, documenting the installation of our flying animals, here and, at the top of this post and beneath this text, there's a series of photographs taken from the exhibition itself. At some point in the near future, I'll post more images detailing the development of the exhibition and some of the concepts we went through in designing and manufacturing the display. Once again, thanks to everyone who helped us out with this project and, for those helping us on the stand over the next few days, thanks in advance. Again, it'd be great to see some Pterosaur.Netters there, too: entry is free and, behind us, you've got the entire Royal Society Summer Science Festival to run around (and there's some really cool stuff in there, too. Obviously not as cool as our display, though). Details can be found here. Anyway, enough blurb: on with the images. Click to enbiggen.


The whole schebang: two giant walking azhdarchids, three flying jobbies, a considerable number of display boards and some bemused onlookers.


Mike O'Sulivan and Luke Hauser, dedicated pterosaur groupies and student volunteers, pose next to our life-size male Pteranodon image. Note that while Pteranodon is big, both Mike and Luke were in the loo when height was being dished out*. Hence, it may appear a little smaller in life.

*Only joking, guys. You're both fine, upstanding examples of the male form. I mean, look at Luke there. Look at Mike lean. Pwhoar.


Our female azhdarchid, who became known as Quetza, grabs Dinner, the hapless baby titanosaur. Kids love this. And by 'love' I mean 'question why we're so heartless'. And by 'question why we're so heartless' I mean 'strongly object'.



The head of Bamofo, our big male azhdarchid. While there's plenty of goofs on him, Bamofo is my favourite model: part azhdarchid, part Terminator, part King Kong: all foam.


The guys next to our gallery of pterosaur busts. Pteranodon and Tupandactylus are taking great interest in Luke's hair, and Coloborhynchus is about to take a chunk of Irish from Mike's arm.


What giant pterosaurs look like when you view them from above. If I was feeling trite, I'd call this a 'pterosaur eye-view'. Thankfully, I'm feeling stern and not in the mood for such things, so I won't.



Two of our flying models, complete with RAF roundels to commerorate the 70th anniversary of the Battle of Britain. I genuinely had nothing to do with them and, being suspended 10 m in the air and well out of reach, I've decided to learn to like them.

Sunday, June 20, 2010

The Brotherhood of Leathery Wings goes to London


I’ve got a habit of withering on for ages when blogging, but that can’t be the case today: in a few short hours I’m off to London to install the University of Portsmouth/Royal Society ‘Pterosaurs: Dragons of the Air’ exhibition with my colleagues, Dave Martill and Bob Loveridge, along with a bunch of student labourers/slaves/groupies that we keep with us at all times. The last few weeks has seen us working like Japanese beavers trying to get everything finished (hence the lack of posts here) but, happily, we’ll be on display on London’s Southbank from the 25th of June to the 4th of July. More specifically, we can be found spread between the interior and exterior of Royal Festival Hall (see map, taken from a presentation I gave ages ago on the exhibition, below), not too far from Waterloo train station and the London Eye.


We’ve got 5 (count ‘em) giant azhdarchid models (two of which are standing on the ground as the world’s first Haenamichnus-inspired parasagittal terrestrial azhdarchid models), 13 pterosaur busts representing a broad sweep of their diversity, a life-size Pteranodon to have your photograph taken alongside and more information on pterosaurs than you could shake a stick at. It was a mammoth amount of work and special praise should be given to the students and other volenteers who put in so many hours in exchange for no more than a few pints of beer and, bizarrely, Southern Comfort and Coke (you know who you are). Simply put, these chaps were the cogs that helped our leathery-winged machine run smoothly, so they deserve considerable amounts of kudos, presents and praise.

You can meet our workforce at the exhibition and, in addition, we'll have several tamed pterosaur experts to chat to while you’re there. Along with myself, Dave and Bob, the likes of Darren Naish and Andre Veldmeijer will be dropping by to discuss all things pterosaurian. Two pterosaur-researching postgraduates from UoP, Richard Hing and Steven Vidovic, will also be on hand. The whole event, part of the biggest-ever Royal Society Summer Science Festival, is totally free to enjoy and should make for a great day out. It’d be fantastic to see some of the Pterosaur.Net readership there.


Right, I have to dash, but more on the exhibition will be posted when I get back. In the meantime, please enjoy two new images of giant azhdarchids penned back in January to advertise the exhibition. The image at the top shows our big male, Bamofo, terrorising some baby tyrannosaurus and, adjacent to this text, is the graceful Mistress swooping over a mudflat with bathing sauropods. See you all in London!

Tuesday, May 18, 2010

How a giant ape nearly brought flightless pterosaurs to cinema screens


I've not kept it much of a secret that I’m a big fan of King Kong or, at least, the 1933 and 2005 versions (you can keep your ‘76 and Toho incarnations, thanks). There was something about the mythos of the film that excited me even before I had seen it so, when I was eight and my family saw the ’33 Kong being shown on late night TV, we grabbed it on video tape and I got up especially early before school to watch it. I only managed to see a brief glimpse of Kong himself before I had to leave for school, but that was enough to ensure that I resumed my viewing as soon as I got home. Almost 18 years later, I can still remember watching the charging Stegosaur for the first time, or that Brontosaurus chucking sailors around a swamp before chasing them up the tree. And, of course, the T. rex vs. Kong wrestling match, all framed by the wooden cabinet around our old TV and watched from our comfy blue sofa just left next to the patio door, with the heavy blue curtains closed to keep the glare off the TV.

Sometime later, my sister would record The New Adventures of Superman over virtually the entire thing and leave only Kong’s death atop the Empire State Building as my entire Kong experience. We’re still not talking.

Anyway, things turned out all right: I eventually got a proper copy of Kong and, hooray, Peter Jackson remade the original to generally great acclaim and success in 2005. Yesterday, my day was made when I received a copy of The World of Kong: A Natural History of Skull Island, essentially being a collection of the creature and environment concept art for Jackson’s movie. Tell you what: Weta Workshop, the chaps behind the 2005 Kong special effects, really went to town with their ideas. They literally imagined an entire world, or at least an entire island, for their movie to be based in. In essence, they embarked on a big speculative zoology project, imagining what may have happened if Skull Island (the mysterious land that the explorers of the film er… explore) held a whole bunch of Mesozoic critters that survived the K/T extinction and continued to evolve. The film shows a handful of the more charismatic creations and environments, but there was buckets more that could’ve gone in. There’s nasty-looking fish, birds, worms and insects, several flying rats, all manner of theropods, ceratopsians and sauropods and even – get this – flying (not gliding) frogs. But they didn’t just go for wild and spectacular stuff: apparently fully immersed in their world, the chaps at Weta imagined the quieter, more sedate biota of Skull Island, including the inclusion of pretty-standard looking storks, egrets and herons in swamps and wetlands. But, and here’s the really cool bit, they also toyed with the idea of flightless, cormorant-like pterosaurs.

How cool would that have been? Secondarily flightless pterosaurs on film! And pterosaurs that are really, really far removed from those that we know and love! Sadly, it wasn’t to be but, still, it’s closer than almost any other film project I know of. Christened Axiciacephalus curia (see image at the top of this post; by Weta artist Johnny Brough), the Weta flightless pterosaur is around a metre long, has naked skin and bears long, low jaws filled with isodont, regularly spaced teeth. The nostrils are positioned far back along the jaw and on the dorsal surface of the skull. The neck and body are short but the tail is long, deep and muscular. Weirdly, the forelimbs are heavily modified into short, flipper-like appendages while the hindlimbs are elongate, three-toed and digitgrade. It’s meant to dwell around streams and live in a cormorant-like fashion, diving underwater and propelling itself along with its long legs. It really is very far removed from all things pterosaurian and, frankly, if it weren’t for the text, I would’ve thought it was some sort of weird theropod. Still, it deserves acclaim for being totally different (I thought my goat-tapejarids were good, but they’re blown out of the water here) and, moreover, a short-armed diving pterosaur may not be as crazy as you’d think.


And here’s why
For one thing, while pterosaur forelimbs are considerably more conspicuous than their hindlimbs, most pterosaur legs are not under-developed. As Padian (1983), Bennett (1997) and Habib (2008) have noted, they only appear small in contrast to the enormous heads and arms that characterise pterosaurs: they’re actually proportionate to the torso size and mechanically suited for powerful, leap-assisted takeoffs (Bennett 1997). Moreover, pterosaur swimming trackways indicate that they propelled themselves through water with their feet, not their hands (Lockley and Wright 2003; see adjacent image from the same paper. Illustration by Judy Peterson). Therefore, it’s not impossible to imagine a situation where a specialist wader pterodactyloid – a ctenochasmatoid, say – became secondarily flightless and, as wading turned to swimming, developed longer, more robust hindlimbs. Simultaneously, a diving animal would almost certainly reduce the size of its drag-inducing and now largely-useless arms, but still maintained some of their aerofoil properties for use as flippers. It’s a stretch, sure, and I’m not really sure the final product would look like Axiciacephalus, but I wouldn’t rule it out.

There's loads more we could say about this, but I don't really have the time. Still, it's pretty neat that flightless diving pterosaurs came close to being put on film and, actually, are a pretty groovy idea. In retrospect, you can see why Axiciacephalus didn’t make it into Kong 2005: although neat in its own way, it’s hardly as attention grabbing as the big tyrannosaurs, brontosaurs and gorillas that lived nearby. Certainly, it would’ve been a very different movie if Axiciacephalus and his more sedate chums had featured heavily. Anyway, must dash: I’ve got to go flip a giant pterosaur.

References

  • Bennett, S. C. The arboreal leaping theory of the origin of pterosaur flight. Historical Biology, 12, 265-290.
  • Habib, M.B. 2008. Comparative evidence for quadrupedal launch in pterosaurs. Zitteliana, B28, 161-168.
  • Lockley, M. G. and Wright, J. L. 2003. Pterosaur swim tracks and other ichnological evidence of behaviour and ecology. In: Buffetaut, E. and Mazin, J. M. (eds.) Evolution and Palaeobiology of Pterosaurs, Geological Society Special Publication, 217, 297-313.
  • Padian, K. 1983. Osteology and functional morphology of Dimorphodon macronyx (Buckland) (Pterosauria: Rhamphorhynchoidea) based on new material in the Yale Peabody Musuem. Postilla, 189, 44 pp.
  • Weta Workshop. 2005. The World of Kong: A Natural History of Skull Island. Pocket Books, London, 223 pp.

Saturday, May 15, 2010

Embarrassing questions on Quetzalcoatlus


You can’t queue up at a supermarket checkout nowadays without being bombarded by celebrity lifestyle magazines. They glare at you from the impulse-buy shelves with paparazzi shots of stars looking flabby, pregnant, boozy or unhappy and garish, block capital headlines scorn celebs for revealing their mortal flaws. There is probably a deep-seated psychological reason to their popularity, perhaps reflecting the desire people have for gossip or reassuring somewhat insecure readers that it’s OK, people with stars on Hollywood Boulevard aren’t perfect either. The thing that strikes me, though, is that a lot of the people splashed all over the front pages of these rags have very little substance behind their fame, becoming famous because they took they posed semi-nude for a tabloid newspaper, are related to someone else in the public eye or appeared on telly for five minutes on a reality TV show. These are the empty celebrities, the ones that you assume have some reason for being known but, when investigated in more detail, are actually quite devoid of substance. It’s rare that these tabloid-fodder achieve international fame: to do that, you’ve at least got to be associated with an internationally-released product or hung-out in high-profile political circles. In some respects, then, becoming a real international household name requires a little more substance than your local, lower-grade celebrities. Talent, though, is handy but not strictly necessary.

There are definitely fossil animals that are the equivalent of A-list celebs, the sort of critters that every five year-old knows and that press releases strive to mention, no matter how tangential their work is to them, to gain more kudos. They’re the animals that the public know and love, the likes of Tyrannosaurus, Triceratops, woolly mammoths and sabre-toothed cats. Typically, these animals do have some substance to them: while their taxonomy may be confused or controversial, they definitely ‘exist’. Some pterosaurs are in this club too, with Pterodactylus (or probably ‘pterodactyls’) or Pteranodon being at the top of the list, and Quetzalcoatlus, everyone’s favourite superpterosaur, just behind (detail of a new image above). Thing is, though, Quetzalcoatlus may be a fraud. Yes, that’s right: there may be so little substance to its existence that its status as a household palaeontological name is undeserved: it’s a local celeb masquerading as a big shot. That’s controversial stuff and, no doubt, several of you have just sprayed your monitor with coffee shot through your nose at the very idea of such a thing. But mop up that liquid, dry the screen off, and we’ll see why I’m suddenly being so nasty to one of the cornerstones of Azhdarchidae.


Giant, yes; diagnostic, maybe not
As I’m sure you all know, Quetzalcoatlus stems from the Maastrichtian Javelina Formation of Texas. Remains of several animals that would be referred to this genus were found from 1972 – 1974 and were briefly described by their discover, Douglas Lawson, in 1975 (Lawson 1975a). Quetzalcoatlus was erected in the same year (Lawson 1975b) with fragments of a giant left wing (including a famous complete humerus, TMM 41450-3; see image, above) being used as the holotype for the type species, Q. northropi Lawson, 1975b. A bunch of smaller individuals that were represented by substantially more complete remains were discovered at the same time and initially referred to the same species (Lawson 1975a, b) but, later, were said to be sufficiently distinct from Q. northropi to deserve their own species (Kellner and Langston 1996). Pending their complete description, however, Kellner and Langston simply called them ‘Q. sp.’ for their work on the Quetzalcoatlus skull.

That all looks above board on the surface, but it doesn’t take much digging to find several massive holes. Firstly, despite the wealth of material that has been referred to it, neither Quetzalcoatlus or Q. northropi have ever been given a rigorous taxonomic definition*. To my knowledge, only Nesov (1991) has had a stab at a Quetzalcoatlus definition but his listed characters are either not unique to Quetzalcoatlus or of questionable validity, so his work is not really useful here. This leaves us without a diagnosis and, accordingly, we simply cannot know if Q. northropi is a valid species or not. What’s more, with Q. northropi being the type species of Quetzalcoatlus, the entire genus must go if the former is sunk.

*You could get away with this sort of stuff in the 1970s, but it’s much harder to be taxonomically slack nowadays. The ICZN (the body that regulates naming of zoological specimens) has recently tightened its rules considerably to make sure that new taxa come with proper holotype allocation, diagnoses and all other due practises (e.g. article 16, International Commission on Zoological Nomenclature 1999), so messes like the one under discussion here should – in theory – eventually become a thing of the past.

In my eyes, this is quite a real possibility. Pterosaur limb elements aren’t normally named because they are not considered diagnostic at generic or species levels: taxa that are based on limb elements alone have been considered nomina dubia by later authors. ’Santanadactylus’ spixi - a set of wrist bones - and Palaeornis cliftii - an isolated humerus – have both fallen into this trap (Unwin 2003; Witton et al. 2009). Unless Q. northropi is unusually distinctive, it’s possible it may be binned too. Adding more concern to this worryfire is that, so far as I can see, the Q. northropi humerus doesn’t look that different from other giant azhdarchid humeri (e.g. Padian and Smith 1992; Buffetaut et al. 2002) and the existence of these other giants nullifies the possibility of using size as a diagnostic feature (though this would be dodgy anyway). The other Q. northropi elements are so scrappy that they’re probably of very little taxonomic utility and preclude the use of limb element proportions in a diagnosis, too. Call me cynical if you like, but it looks like this could be an uphill struggle to me.


The plot thickens
There’s more. With no definition for Quetzalcoatlus, the referral of the Q. sp. material (including that depicted above, from Kellner and Langston 1996) to this taxon is also questionable. The Q. sp. material is what people refer to when talking about the detailed anatomy of Quetzalcoatlus, but we need to be careful: there has never been any justification printed for the allocation of Q. sp. to Quetzalcoatlus: we’ve just been told it’s similar to Q. northropi and can therefore be placed in the same genus. Thing is, Hatzegopteryx, Arambourgiania and Zhejiangopterus are pretty similar animals to Q. northropi too, so why can’t the Q. sp. material been popped in one of these genera instead? You can't argue taxonomic provinence in this instance, either: it's highly likely that there is more than one azhdarchid genus in the Javelina Formation (see my thoughts on this here), so you can’t suggest allocation of Q. sp. to Quetzalcoatlus through association alone.

To be clear, I'm not saying that Q. sp. itself is of questionable validity - whatever you want to call it, Q. sp. is definitely a valid, diagnosable species, I’m just iffy about its allocation to Quetzalcoatlus at present. Note, however, that the story continues outside of material referred to Quetzalcoatlus, too: the status of Hatzegopteryx may also hang in the balance. I don’t have time to go into that now, though.

So, what next?
The resolution of all this is, in my view, quite straightforward. Eagle-eyed readers may have read between the lines of this post and realised that, despite it’s fame, popularity and unearthing almost 40 years ago, there is almost nothing written or illustrated of Quetzalcoatlus. The issues highlighted here will not be resolved without this data and, frankly, a few good photographs and descriptions of Q. northopi would give all the information we need to get started. There is, in fact, a bit of an elephant in the room about Quetzalcoatlus and, foolish though it may be for a bloke looking for a job in the pterosaur corner of palaeoindustry to be so outspoken, it should be flagged up. Without mentioning any names, the Texas Memorial Museum has placed a strict embargo on the release of information about Quetzalcoatlus until the full monographic description has been properly published. This has been promised since at least the 1980s (Langston 1981; Kellner and Langston 1996) and, in the meantime, getting access to the material seems to be extremely difficult. I asked to see the material back in 2006 and was told no. Colleagues of mine have asked the same, and got the same answer. The few friends of mine that have seen the specimens are sworn to secrecy and, if they want to publish even itty-bitty snippets of information about them, they have to ask permission first.

If you ask me, this is all a bit rotten. The Society of Vertebrate Paleontology’s ethical mission statement states that vertebrate palaeontologists of the world are here to:

  1. To advance the science of vertebrate paleontology throughout the world;
  2. To serve the common interests and facilitate the cooperation of all persons concerned with the history, evolution, ecology, comparative anatomy and taxonomy of vertebrate animals, as well as the field occurrence, collection and study of fossil vertebrates and the stratigraphy of the beds in which they are found;
  3. To support and encourage the discovery, conservation and protection of vertebrate fossils and fossil sites;
  4. To foster the scientific, educational and personal appreciation and understanding of vertebrate fossils and fossil sites by avocational, student and professional paleontologists and the general public.
From the SVP Constitution, Article 12, Code of Ethics.


Aside from the point 3 in this list, it seems that the decades-long embargo on the Quetzalcoatlus material isn't really in keeping with these guidelines. I mean, I get embargoes. I get 'gentlemen's agreements' about publishing rights. But 40 years to publish a specimen description while simultaneously being very cagey about giving access to the material? Seriously guys, what's going on? I'm not sure there's quite enough ground here to go stampeding to the SVP ethics committee or anything, but when is this material going to be properly published and freely available to see?

References

  • Buffetaut, E., Grigorescu, D. and Csiki, Z. 2002. A new giant pterosaur with a robust skull from the latest Cretaceous of Romania. Naturwissenschaften, 89, 180-184.
  • International Commission on Zoological Nomenclature. 1999. International Code of Zoological Nomenclature (4th Edition). The International Trust of Zoological Nomenclature, 1999.
  • Kellner, A. W. A. and Langston, W. Jr. 1996. Cranial remains of Quetzalcoatlus (Pterosauria, Azhdarchidae) from Late Cretaceous sediments of Big Bend National Park. Journal of Vertebrate Paleontology, 16, 222-231.
  • Langston, W. Jr. 1981. Pterosaurs. Scientific American, 244, 92-102.
  • Lawson, D. A. 1975a. Pterosaur from the Latest Cretaceous of West Texas: discovery of the largest flying creature. Science, 185, 947-948.
  • Lawson, D. A. 1975b. Could pterosaurs fly? Science, 188, 676-677.
  • Nesov, L. A. 1991. Gigantskiye lyetayushchiye yashchyeryi semyeistva Azhdarchidae. I. Morfologiya, sistematika. Vestnik Leningradskogo Gosudarstvennogo Universiteta. Seriya 7, 2, 14-23.
  • Padian, K. and Smith, M. 1992. New light on Late Cretaceous pterosaur material from Montana. Journal of Vertebrate Paleontology, 12, 87-92.
  • Unwin, D. M. 2003. On the phylogeny and evolutionary history of pterosaurs. In: Buffetaut, E. and Mazin, J. M. (eds.) Evolution and Palaeobiology of Pterosaurs, Geological Society Special Publication, 217, 139-190.
  • Witton, M. P., Martill, D. M. and Green, M. 2009. On pterodactyloid diversity in the British Wealden (Lower Cretaceous) and a reappraisal of “Palaeorniscliftii Mantell, 1844. Cretaceous Research, 30, 676-686.