Friday, December 27, 2013

So this is Christmas, and what have you done?...

...asked John Lennon and Yoko Ono, in November 1972, before most of the Pterosaur.net crew were even born.

This particular song is guaranteed to make me grind my teeth as I elbow my way through Aldi with a basket full of mince pies and a wet umbrella tucked under my arm. Yes, there's a bit of 'Bah Humbug' in me, I won't deny that, but that's not the whole reason. You will find other seasonal novelty songs on my iPod all year round, so why, I hear you ask, do I hate Happy Xmas (War is Over) with all my heart?

It's the opening lines really. So this is Christmas, and what have you done? Another year over, a new one just begun.

Groan. As if we need to be reminded that another year has shot by, and we haven't done half of the things that we wanted to. It's like being told off by your parents for dossing around in your pyjamas all day, instead of doing something useful.

But we haven't been dossing around in our pyjamas in the NHMUK pterosaur collection, contrary to any stories that you might have heard. It's been a busy year, as usual. I'd like to tell you how many collection visitors have been this year, but I don't have access to the stats right now, as I'm writing from the debris-strewn dining table at the Steel / Hume residence. Instead, let's go through the diary, and see what the NHMUK pterosaurs got up to in 2013.

The snout of the 'cookie-cutter' pterosaur Istiodactylus was CT scanned for a PhD project. At this stage I have no further information on what, if anything, this showed. The same project was to include SEM work on a single tooth. Several researchers are interested in this specimen, so I'm sure that this data will be useful to someone. Sadly, the student has decided not to continue with this project, making this the second time that a PhD project on Istiodactylus has stalled (if you'll pardon the pun). Perhaps it was cursed by the collector, Hooley, all those years ago.

Speaking of collectors, Heather Middleton kindly loaned her collection of Kimmeridge Clay pterosaur bones and teeth so that they could be photographed by those lovely chaps in the NHMUK photo studio. Some of Heather's specimens might feature in the pterosaur chapter of the forthcoming field guide to the Kimmeridge Clay (available in all good bookshops), which is edited by none other than Dangerous Dave Martill. He is also solely responsible for the pterosaur chapter, I believe. Heather's collection is far superior to the NHMUK material, and includes quite a few nice teeth.

The latest Isle of Wight pterosaur, Vectidraco, was described and named early this year.  For those that missed it, the specimen is a small pelvis that was found by a young girl about two years ago, and donated to NHMUK by her. News reached the ears of 'The One Show', a popular tea-time television programme, and to cut a long story short, I had about 24 hours notice to prepare the specimen and myself for live TV on April 11th. The museum's Head of Conservation made a mount and a box so that the specimen could travel safely to the studio without being handled. Daisy, the girl who found the specimen, was there too, with her whole family, but was a bit overwhelmed by the whole live TV thing, and went all shy. I was too busy trying to hold my tummy in, and worrying that I would forget the name Vectidraco.

I didn't make it to the Pterosaur Symposium in Rio de Janeiro this year, as it wasn't as heavily subsidised as the one in Beijing in 2010. But several people were kind enough to send me copies of the abstracts volume. Much appreciated. I have a couple of spares, if anyone missed out.

One of the Solnhofen pterosaurs travelled to Southampton University for a session in their big CT scanner. Unfortunately this didn't go as well as hoped. The images showed bedding in the matrix, but no contrast between it and the bones. Later in the year, I was back at Southampton again for the Wealden symposium, which was very well-attended. Dave Martill spoke about Istiodactylus. And the Great Wall of China.

One of the last big events of the year was 'Blast From the Past' at Dinosaur Isle. This is an open day at the museum in Sandown, Isle of Wight, with local collectors, palaeontologists, archaeologists and artists all showing their work and collections to the many visitors. For me it was a chance to see old friends and hear about some recent finds. I was expecting to meet up with Nick Chase to pick up a couple of Pholidosaurus skulls that he'd collected in Dorset in the late 1980s, but to my surprise he also donated a few other specimens from the Island. These include a few bits of small pterosaurs, and a theropod humerus. I also saw Mick Green for the first time in ages, and he brought along most of his pterosaur collection.

Finally, a painted cast of Dimorphodon has been exchanged with AMNH (for some casts of Mongolian dinosaur bones) and a cast of the snout of Istiodactylus will probably be exchanged with Dinosaur Isle for a cast of their new small croc. 

That's not all, of course. I won't bore you with all the croc-collection comings and goings, as presumably you came here to read about pterosaurs. So I will stop here, put on my pyjamas and watch my new DVD that I got for Christmas. It's called 'Flying Monsters' and it should be really good, because Sir David Attenborough is in it, and it has a blood-stained Dimorphodon on the front cover...


Wednesday, October 23, 2013

Yes, it's from the Solnhofen. Really.

I'll just leave this here. Enjoy.

Sunday, October 20, 2013

Ornithocheirids on show


Yes more photos from Frankfurt, this time of a combination display that has more or less everything. First off there's a superb mounted animal on the wing hanging from the ceiling. Then there is a cabinet containing a cast of a superb specimen on Anhanguera laid out in something I assume is close to the mid-point of preparation, and finally there is the whole prepared piece: the skull is separated and on show, and running up the side of the cabinet is the assembled wing.



Also there is a sectioned longbone, showing the wonderfully thin bone walls. This one is especially nice since it has, unusually, not been infilled with matrix making it really clear and the internal trebeculae are also quite clearly preserved (and apparently calcite crystal free).

It's quite a set and does show just how much information can be crammed into surprisingly little space and while I can't read the text of the main display it is clearly talking about burial, preservation, preparation and the reconstruction of the animal. Great stuff.






Saturday, October 19, 2013

Quetzy flying high


 I've just returned from a very quick trip to Germany, dropping in at the Solnhofen Museum, Jura Museum Eichstaett and then onto Frankfurt in just 3 days. The primary purpose was actually looking at birds ad various feathered creatures but of course I took in more than a few pterosaurs too. There's a few more photos to come on that score including one extraordinarily important specimen that few will have seen and many will not even have heard of. In the meantime though, have a tanking great azhdarchid.

This one is beautifully mounted and is several meters off the ground in the main hall of the Senckenberg Museum in Frankfurt and all but soars about the dinosaurs. Rather nicely one can stand almost right under it as well as seeing it from near eye-level from the higher balconies of the galleries above. Plenty of museums now have a cast / sculpt like this of a giant azhdarchid / Quetzalcoatlus, but this is a nice one (if imperfect) and while this may sound odd, it's nice that it is so high up in the rafters, it still looks big from ground level, but it gives a better sense of scale when you get to its level and discover that it is clearly even larger than it looked from below.


Sunday, October 13, 2013

New pterosaurs, new phylogenies


People with an interest in pterosaurs will probably be aware of the recent passing of Wann Langston Jnr, the Texan palaoentologist who was responsible for a lot of the popularizing of Quetzalcoatlus. I was lucky enough to meet Wann at the 2007 Flugsaurier meeting in Munich where he was able to attend, despite being well into his 80s. Wann’s work covered a great many aspects of Mesozoic reptiles and the recent festschrift that has been published in his honour covers a raft of different taxa.

Of interest to us though are three papers on pterosaurs that between them name four new taxa! That’s quite an effort for a single volume that is not even devoted to pterosaurs. However, what I want to talk about here is the phylogeny that appears in the paper by Brian Andres and Time Myers. Many will know that since 2003 pterosaur phylognies can broadly be divided into two camps – those which look more like that of Dave Unwin’s 2003 paper (the one shown here in red and blue is from the Darwinopetus description) and those which resemble Alex Kellner’s effort from the same year (the one shown here is from the Wukongopterus description). They are not actually that different from each other, both have the same general arrangement of taxa but with some difference. Kellner-type phylognies have anurognathids before dimorphodonitds, Unwin the reverse. Unwin-types have ornithocheiroids before the ctenocasmatids, Kellner the reverse. Both have the rhamphorhynchines immediately before Darwinopterus and kin and those coming before the origin of pterodactyloids and both have dsungaripterids close to the azhdarchoids. In short, there’s a way to go to get a consensus and there are some fairly clear and consistent contradictions, but they are not so far apart.


 Interestingly, back in 2007, Brian Andres presented on some of his PhD work where he talked about how the two might be coming together, and Dave Unwin have a similar talk in Beijing in 2010. However, the phylogeny in this paper (below) is really rather different to both of those. This is the latest version of Brian’s analysis which has already popped up in a couple of papers, but frustratingly, the actual core of this (i.e. the actual character list and coding) still isn’t published –owing to the interminable delays on The Pterosauria book - so there’s no way at the moment to see what is causing these shifts.


The contrasts are quite dramatic though. Neither the dimorphodontids nor anurognathids are at the base (or close to it) of the phylogeny, but instead it is the eudimorphodontids and the anurognathids are in fact lying more derived than Darwinopterus and close to the pterodactyloids! The dsungaripterids are also now not sister taxon to the azhdarhoids, but lying within the clade as sister taxon to the thalassodromids and with the tapejarids as a basal clade to these plus the azhdarchids+chaoyangopterids.

In short, if anything, the phylogenies are getting further apart. Now I would expect them to converge again sooner or later: after all, there is only one correct solution. But as often lamented (and in particular by Darren), pterosaur phylogenies are generally rather character poor compared to many analyses of archosaur clades so there is much more to come. That said, I think some of the problem comes from the continued practice of doing analyses that cover the whole of the Pterosauria. Surely we are at the point where the rhamphorhynchoids and pterodactyloids are well separated and there’s no need to repeatedly include both in every analysis – it’s probably not helping the resolution of some trees where large chunks of the characters or states needed to help resolve one clade won’t add anything to the other. Devoting more time to better characters for smaller groups will probably be more productive than continuing to code up large numbers of taxa where large numbers of characters are inappropriate.

Anyway, that’s my 2p on the problem. Certainly the current conflicts are interesting and I look forwards to seeing what characters are supporting some of these unorthodox positions – there are likely to be some interesting convergences and codings in there. Obviously it’s hard to say much without the underlying data, but at face value I’m not overly convinced by some of those positions, but it will be especially interesting to see what these new positions mean for things like character support of branches and if it calibrates better temporally than the other current competing ideas. Now, we just need the book to get finished….

  
Andres, B. & Myers, T.S. 2013. Lone Star Pterosaurs. Earth and Environmental Science Transactions of the Royal Society of Edinburgh. 103: Issue 3-4, p 383-398.


Tuesday, September 3, 2013

SVPCA 2013 - a pterosaur spectacular


Well SVPCA (Symposium for Vertebrate Palaeontology and Comparative Anatomy) for 2013 has just ended in Edinburgh. As per usual, there was a good set of pterosaur-related talks and the P.net crew was heavily involved. Mark spoke about azhdarchid neck evolution, I had a talk (which included Mike Habib as an author) on a new Rhamphorhynchus specimen with new evidence on their diets and Darren spoke on sexual selection in the fossil record which naturally included pterosaurs (and which included me as an author). Not bad at all really, but then there was the fact that for the first time since way back in Munich 2007, nearly the entire P.net crew was together!

As can be seen here we have (L-R), Luis Rey, Mark Witton, Darren Naish, Lorna Steel, me, Mike Habib (over from LA), Ross Elgin and John Conway. We were only short of Dino Frey and Helmut Tischlinger, and as neither rarely leaves the confines of southern Germany. I don't think we've ever had this many people together - even Dino didn't make the Munich conference that ultimately spawned the website, and certainly when the idea formed about the site we weren't all together so this might be the biggest set of us ever. Ah fun times (as rather demonstrated by the second photo below).

Anyway, while on the subject of groups of people talking pterosaurs in the UK, the announcement was formally made that the next 'Flugsaurier' meeting will be in 2015 and hosted at Portsmouth. Dave Martill will be leading the charge, with myself, mark, Dave Unwin and others helping. The plan is to link this (in terms of time) to SVPCA that year (which does not yet have a venue) so that Flug will go immediately before or after and so that hopefully a few people who have come to the UK for the pterosaurs may stay for the other meeting (or vice versa) and both conferences may benefit. SVPCA is usually in early September and so while we do not yet have a definitive date for Flugsaurier, expect it to be the end of summer 2015 with a date between the last week of August and third week of September. Fieldtrips are planned to both the Jurassic Coast and classic localities for things like Dimorphodon as well as to the Isle of Wight for Istiodactylus. Keep your diaries free!

Saturday, August 24, 2013

Pterosaur origins and the ‘protopterosaur’

One very interesting aspect of Mark’s new book is his take on the pterosaur ancestry issue. From decades people have reproduced an illustration by pterosaur researcher Rupert Wild that presented a hypothetical pterosaur ancestor. It was something rather lizard-like (since he considered pterosaurs closer to the prolacertiforms than current mainstream thinking of them as sister-taxon to the dinosauromorphs) but with elongating fingers and the beginnings of wing membranes. While often commented on that this probably wasn’t a great model anymore, it was pretty much the only nice illustration out there and so kept being re-used, and it did at least provide a conceptual idea of just what such an animal might look like. Lacking any transitional forms for pterosaurs, we do have to imagine a bit, and as I’ve long said, this is one area where palaeoart is key as it can communicate ideas like this to a lay audience in a way no amount of even florid prose can realistically do.

Mark’s approach however was not to produce a single transitional form but several of them. He worked his way through something very close to an archosaur so something nearly a pterosaur over three distinct stages. That gives a much more thorough take on this issue and allows him to explore not just what these things may have looked like, but also the evolutionary pressures and problems at different stages of their evolution. What’s interesting for me is that it also contrasts and compliments with something that I’ve been working on.

Most of you are probably aware that some years ago a major academic book was promised on the pterosaurs. The damn thing seems to be on near-permanent hiatus (I wrote my chapters back in 2008) but as part of the introduction I did on pterosaur origins I got together with Luis Rey and produced an updated ‘protopterosaur’ to take into account both the ornithodires, but also new data and hypotheses on wing evolution, basal pterosaurs and other issues. Luis has been kind enough to let me put up his effort and Mark has also passed on one of his intermediates for comparison (obviously these are copyright to these respective artists).
Marks' version of Rupert Wild's 'protopterosaur' (left) and his own suggested animal (right)
While obviously the art style is very different and we’ve got one image to covers everything (whereas Mark was working in stages) there are some strong similarities in places. The area of pterosaur origins came up in a chat between us perhaps two years ago and we soon discovered we’d both been producing protopterosaurs and that we’d independently struck on some strong connections. Sure this is all hypothetical, but it is interesting that we’ve headed down some similar lines in places starting from the same point and with the same assumptions.

For completeness and as a general guide, here’s the figure caption I produced for Luis’ art. I would have normally gone for a darker colour and less bright pattern to emphasise this as a small animal, vulnerable to predators, but when you ask Luis to illustrate and animal “not bold colours” should never be in your description. Still, the other bits of anatomy I wanted and the details are all in there and reflect various issues of pterosaur origins:
Luis Rey's version
Note that this is not being presented as a scientific hypothesis but is used to illustrate some of the profound changes that must have occurred to the ancestral species to become a pterosaur. This image was created in partial tribute to the oft reproduced ‘protopterosaur’ image by Wild (1984) which imagined a transitional form between prolacertiforms and pterosaurs. For this piece the ancestor was considered to be a dinosauromorph and with anurognathids or dimorphodontids as basal pterosaurs. The animal also includes new information on pterosaurs evolution (e.g. Bennett, 2008 on the origin of wing folding) to illustrate how some parts may have evolved. Different parts of this animal have been ‘allowed’ to evolve at different rate and thus some are much closer to the ornithodiran condition, and others to the pterosaur condition. Note the following features: the animal is arboreal; an archosauromorph-like head which is relatively short and tall, with and antorbital fenstra and archosaurian teeth; enlarged pterosaur-like orbit; head, neck, trunk and hind-limb proportions close to that of Scleromochlus; a relatively short and flexible tail exhibiting only a small tail-vane that is similar in shape to juvenile Rhamphorhynchus; an elongated wrist, but with no pteroid or propatagium; large manual digits 1-3 with large claws, a straight an elongate fourth finger that is still shorter than that of pterosaurs, this retains a small, anteriorly directed ungual; absent fifth finger; a relatively broad-chorded brachiopatagium that reaches only to the knee, but which is replete with actinofibrils; a simple archosaurian pes with an unmodified fifth toe and no webbing between the toes; a very limited uropatagium covering only parts of the legs and integrating with the base of the tail; only limited coverage of pycnofibers with much of the body still covered by scales.

Friday, July 12, 2013

More on Rhamphorhynchus biology

Over on his blog, Mark has put up a post about a recent popular science article on Rhamphorhynchus and in particular stuff on feeding and foraging behaviours. It's well worth a read and shows off a nice privately held specimen (that's mummified!) and discusses the undying issue of skim feeding. That's one of those ideas that just doesn't seem to go away no matter how hard it gets hit and Mark dissects the problem once again.

On a related note, the article Mark mentions was produced by Fred Weber for a French magazine. Mark did the art for it and similalry I borrowed to Witton materials for a piece I did with Fred on pterosaur ecology. It's in French (I wrote, he translated) but it does include some nice photos and art and can be downloaded from my site here if anyone is interested (scroll down).

Thursday, June 27, 2013

Pterosaurs: Natural History, Evolution, Anatomy – a review





Right, let’s get the obvious bit out the way first. I’ve known Mark Witton for more than 5 years now and while we’ve never published a paper together, have certainly worked together, reviewed each other’s papers at times, and spent much time talking pterosaurs and of course doing things like Pterosaur.net. In short, he is both friend and colleague, and some people reading this review may not know that. However, I do also do my best to be fair and this is as honest a review as I feel I can produce. Added to that, while I’ve known this was in production for a long time, I can’t recall more than a couple of very minor conversations with Mark about the book – I really knew very little about what he had done, how and why, before I saw it, so I was coming to the book from a pretty unbiased standpoint in that sense at least.

Anyone familiar with pterosaurs will know that, kids books aside, there have barely been a handful of pterosaur books, well, ever. We have Seeley’s 1901 effort that is still fascinating for the professional, but just a wee bit dated. Wellnhofer’s 1991 Encyclopedia is a classic but again has faded a bit in recent years with so many new forms coming out and much more research, though it’s still a ‘must have’ for any serious pterosaur researcher or enthusiast. In 2004 David Unwin had his Pterosaurs of Deep Time which was a major update from Wellnhofer, but very different in style to that one consisting of a lot more text and relatively few figures, though lots of photos of key specimens. There has also recently been Andre Veldmeijer’s one (illustrated by Mark as it happens) which is (so I understand, I have only the Dutch and not the English version) relatively non-technical and aimed at a more general audience. So right off, Mark’s tome joins a pretty sparse collection, and any serious contribution is therefore going to be most welcome to this band.


In overall appearance it’s almost an exact fit between Wellnhofer and Unwin – with a great deal of text and detailed information, but not at the expense of numerous figures, both artworks (i.e. life restorations and palaeoart) and diagrams and more technical illustrations (graphs and skeletons) in addition to a good number of photos, though this is one area where it is a little short. Where Wellnhofer was organised primarily by time period, and Unwin by body parts or ecology / behaviour, the majority of Mark’s book is taxonomic, with a (nicely colour coded) chapter for each clade. It’s well put together, has a nice font (I’m not any kind of font geek, but it is annoying when something looks inelegant on the page) and is on high quality paper, the printing seems good too and the reproductions of the artworks and figures are good.

I’ll do the criticism bit first and get it out the way as there’s not much to criticise. In addition to the relatively limited number of photos, the introductory and concluding parts of the book are relatively short, and so while the main bulk is well done, there is a feeling that the overall picture of pterosaur evolution and the wider context of them in the Mesozoic is not given much space. It was also odd that there were no ‘further reading’ bits or a list of websites – one hopes that this book will inspire more people to read up about pterosaurs and while I obviously hope P.net will be a source for that, given the real problems pterosaurs do have online (there’s some really major and problematic sites out there) something that would help guide people to the good stuff would have been a useful addition.

My one real criticism would be that it’s a bit of a mix of styles and while Mark’s writing is generally breezy and very readable (and with little sarcastic comments, fun asides and generally friendly tone) but there are quite a few technical terms that get thrown at the reader from time to time that’ll have people reaching for a dictionary. That’s not necessarily a bad thing – I like being challenged, but I’m sure a few general readers will struggle at the first go to follow a few points and the odd paragraph without going to the bookshelf (or more likely, google, some of that anatomical stuff won’t be in your typical paper edition). It does mean though that in places it feel a bit odd with a very readable style littered with words you have to look up - a short glossary would certainly have been a help. Overall it’s not a huge issue though and again, given word limits and the (I assume) intended broad appeal of newbies through to real experts, there is a very difficult balance to strike here and it’s not going to stop people reading it or getting what they want from it.

To be fair though, one cannot cram everything about everything into a book of a limited word length, and so these comments are perhaps more of an observation of the route taken rather than an actual problem that could necessarily have been addressed while keeping the rest of the book the same. To add anything at this word length other stuff would have course have to go, and I’m sensitive that authors have their own intentions (and have to bow to the publishers) and the constraints of the formats. 



Right, with that out the way, let’s get onto the good. It is well written, and should appeal and be educational to those who know little to nothing about pterosaurs, as well as being a generally excellent summary of all things pterosaurian for experts. I found a few nuggets in there I didn’t know about or had long forgotten and the layout of the book is very easy to navigate as a reference piece. It is also accurate and about as up to date as it can be and while already there are new taxa and papers that affect things (such is life) this really will stand for a good few years to come as pretty close to cutting edge. Certainly this is the first book to include Darwinopterus and kin and to bring forwards some of the more recent developments and advances in our understanding of pterosaur biology. At the end of the book Mark argues something parallel to my own paper on the ‘pterosaur renaissance’ – pterosaur research is accelerating in complexity and detail and this book really helps trumpet that and bring it forwards.

The controversial issues are handled really well. Pterosaur research has some major splits within its ranks over some serious issues (origins and phylogeny especially) and Mark is careful to point out where things are contentious and what the alternates are, and why he (or the community) comes done on one side or another. However, he also deals with this pretty efficiently and avoids getting bogged down in details or the endless arguments that afflict some coverage of this kind of stuff. He’s also pretty clear as to what is already in the literature and which ideas are supported by what evidence (the book is superbly well referenced throughout) and when something is new and his own (i.e. this is the first appearance of an idea in the literature) he also makes that clear. Some of these are things various people have been knocking around for a while and if you’ve spoken to researchers or seen discussions online they will be well familiar, but it’s good to see them in print as more formal ideas and some of the evidence that may support them laid out.

The little reviews of each clade are very useful, and each section is broken down into sections on anatomy, locomotion and ecology, with key specimens of details illustrated and a map of the locations of major fossils. Each clade comes with a full skeletal reconstruction and a full life reconstruction alongside, so it’s very easy to get an idea of how each group differed and their diagnostic features and lifestyles. Some of the chapters are very short indeed, but it does make them easy to read and follow and with the subheadings it’s also easy to pick out key data – I think I’ll have an easier time dipping into this to re-read key points or check things that I would with any of the other previous pterosaur entries.




Although I have said I’d have liked to have seen some more photos, the book is very well illustrated. In addition to the skeletals and basic life reconstructions, most chapters have a full-page image or even two of pterosaur palaeoart. Although Mark regularly posts stuff on his blog, almost all the art in the book is new, so there’s no extensive recycling or anything like that. While hardly in ‘All Yesterdays’ territory, there are plenty of images of pterosaurs doing things not normally illustrated and interesting and new approaches to things like colour patterns and layouts of the images – there’s no memes here to be had. The technical figures are even better and are very well done with some nice stylistic flourishes in the phylogenies especially, but overall being very clear and really conveying the key points.

So, summing up. 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. 

Mark P. Witton, 2013. Pterosaurs: Natural History, Evolution, Anatomy. Princeton University Press.  291pp.

Thursday, April 25, 2013

Pterosaur books to know and love, part 3: Pterosaur Trouble

Pterosaur Trouble cover image, by D. Loxton and Jim W. W. Smith, courtesy of Kids Can Press.
What's this? A review of a children's story book on Pterosaur.Net? Isn't this site about pterosaur science, with specimen numbers, refutable hypotheses and that sort of thing? Relax, dear reader: this review is about pterosaur science, and specifically how it can be presented well to even very young audiences without dumbing down, compromising illustration quality or making up nonsensical stories about the past.

Pterosaur Trouble, penned and illustrated by Daniel Loxton, with some illustrative assistance from Jim W. W. Smith, is a recently published work of 'palaeofiction' aimed at 4-7 year olds. It's the second in the Kids Can Press 'Tales of Prehistoric Life' series, following the 2011 Ankylosaur Attack. The short story sees a 10 m span Quetzalcoatlus halting its long journey across Late Cretaceous Canada in search of food, but runs into a vicious pack of Saurornitholestes instead. Along the way, we see various other fauna expected in a story set in the latest Cretaceous North America, including a couple of tyrannosaurs and a herd of Triceratops. As may be expected for a book aimed squarely at young children, the pages are kept largely free of text and only a single page, a final 'information page' on Quetzalcoatlus and Saurornitholestes, has a significant amount of text. The story is thus mostly told through its illustrations, which is what we'll focus on first.


Pterosaur Trouble spread, featuring Quetzalcoatlus and some noisy dinosaurs, by D. Loxton and Jim W. W. Smith, courtesy of Kids Can Press.
Virtual reality
The illustrations of Pterosaur Trouble are entirely rendered through CG animal models composited into photographed backgrounds (Loxton speaks at length about his illustration process in an interview over at the CSI blog). This sort of illustration has become commonplace in children's books on prehistoric life, and, it must be said, has generated some pretty awful bits of art. Sadly, there's probably more bad bits of CG palaeoart around than good ones, and this may create low expectations for Pterosaur Trouble's illustrations. Happily, Pterosaur Trouble dodges the problems of  obviously photoshopped backgrounds and plastic-looking, poorly composited creatures to create images which look pretty convincing (as you can see for yourself with the spreads throughout this blog). I'm not sure that they're 100% photorealistic, which is clearly the effect being sought, but they're pretty durned near. And not in that creepy, Polar Express sort of way, either. I think my 7 year old self would be pretty convinced that I was looking at some photographs. Special mention should go to the little details embedded into some scenes. Feathers float through the air from attacking Saurornitholestes, water splashes reveal the trajectories of the animals making them and reflections are seen in still water.

A chief issue with many pieces of CG palaeoart is inaccurate portrayal of the animals themselves. Pterosaur Trouble largely avoids this problem too, suggesting the mind of Darren Naish, who's listed as the scientific consultant for the book, has been put to good use. The animals look, more or less, pretty good and can be identified as the species they're meant to represent. The basic proportions and appearances of the animals are fairly close to the mark, and I get the feeling that real effort was made to render animals which would satisfy fully fledged palaeontologists as much as children. Again, there are lots of little details to appreciate. The Quetzalcoatlus beak has a chipped and rough appearance reminiscent of the beak of a marabou stork, the back of its neck has relatively long pycnofibres (as indicated by some specimens of Pterodactylus - see Frey and Martill 1998) and the primary feathers of the Sauronitholestes forelimb seem to attach to digit II (on correctly orientated hands, no less). The poses of the animals are also well chosen. There's a much appreciated deficit of roaring and hyperdynamic postures, and the points of view are sensibly placed so that we can clearly see the action, but the animals never look strange and distorted.


Pterosaur Trouble spread, showing Quetzalcoatlus in some Top Gun valley action, by D. Loxton and Jim W. W. Smith, courtesy of Kids Can Press.
As may be expected, I do have a few niggles. The faces and anterior neck regions of the star animals are devoid of fluff, a trope which I wish would politely clear off. Well known fossils of both dromaeosaurs and pterosaurs show that their necks and faces bore filamentous integuments, and we should reflect this in our reconstructions (Sharov 1971; Xu et al. 1999). The Saurornitholestes forelimbs could do with some more feather groups, and both star animals show some slight shrink wrapping on their heads. The uropatagium of the pterosaur attaches to the tail, which has never been found in any pterosaur specimen despite its prevalence in artistic reconstructions, and eye of the Quetzalcoatlus is set way too high in the skull (see my Quetzalcoatlus sp. skull reconstruction, below). Perhaps most glaringly, the wing finger of the pterosaur does not fold up against the body when the animal is grounded. These, and a few other nitpicks didn't really irk me that much however, probably because the overall illustration quality is pretty good and I enjoyed the other components of the book.

Skull reconstruction of Quetzalcoatlus sp., based on Kellner and Langston (1996). Note the ventrally displaced orbit, well below the top half of the skull. From Witton (2013).
Text me
The images of Pterosaur Trouble are embellished with short passages of text on each page which provide details on the accompanying image. The text scores highly for avoiding anthropomorphising its animals too much, a major pitfall of much 'palaeofiction' . Instead, we have the actions of the animals being described more than their emotional states, often with neat bits of information sneaked into the same sentences. For instance, Quetzalocatlus is described as 'a giraffe-sized giant landing as a gently as a dragonfly' at one point. In one sentence we're given a sense of the size, mass and flight capabilities of this animal, and all in concise and evocative language that a 4 year-old could understand. The text is pretty on the ball scientifically, too. Pycnofibres, pterosaur 'fuzz', are described as 'hairlike fibers' rather than feathers or fur. The azhdarchid is said to eat 'anything that walked or slithered', which sounds like a reference to the terrestrial stalking hypothesis of Witton and Naish (2008) to me, and the animal vocalisations are the clicks, coos and chatters of an avian-like syrinx rather than the snarls, roars and bellows of a mammalian larynx. Given that many children's books on prehistoric life simply rehash information from other, sometimes much older children's books on the same topic, or else make mistaken claims that simply aren't true, it's refreshing to see Pterosaur Trouble presenting these new ideas to young audiences.

Pterosaur Trouble spread, showing Quetzalcoatlus apparently approaching Isla Nublar, by D. Loxton and Jim W. W. Smith, courtesy of Kids Can Press.
The story itself has one foot in the science camp, too. The overall premise was inspired by a Saurornitholestes tooth left in a large azhdarchid tibiotarsus, an indication that this dinosaur once ingested pterosaur meat (Currie and Jacobsen 1995). Whether the dromaeosaur actually attacked and killed the azhdarchid in that case is debatable, and I do agree with Currie and Jacobsen (1995) that the body size difference between the dinosaur and pterosaur suggests scavenging activities rather than predation. However, we're all aware that remarkable and unexpected feats of predation can occur in modern animals, such as lions attacking fully grown elephants and adult giraffes, so we can't rule out the occurrence of similar events in the Mesozoic. Happily, Pterosaur Trouble acknowledges this ambiguity on its final page along with a host of other factoids on its star animals. (Anyone interested in the logistics of dromaeosaur predation on pterosaurs should check out this post and its comments at Dave Hone's Archosaur Musings, which go into some detail on these issues.)

I couldn't feel like I've reviewed this book fairly without mentioning one particular part of its story, which may serve as an excellent case study as for how well put together this little book is. At one pivotal moment, the Quetzalcoatlus has to escape its dinosaur attackers, leading to it quad launching into the air while carrying a couple of dinosaurs. How cool is that? This one moment in the story, and its accompanying spread, is an awesome hat-trick of splendidness. Firstly, it reaffirms that Loxton has really been paying attention to the cutting edge of pterosaur research. Pterosaur quad launch is still a fairly fresh idea that, as a fully fledged hypothesis, was proposed as recently as 2008 (Habib 2008). Secondly, it features a simply terrific (and convincing) reconstruction of an azhdarchid mid-launch (below), with dromaeosaurs being cast from the launching pterosaur like feathery rodeo cowboys. Thirdly, it completely disregards the idea of pterosaur as weak, flimsy fliers, showing its star animal breaking free of its attackers and taking off despite being weighed down with unintended passengers. This is yet another nod to new research which indicates that giant azhdarchid humeri were extremely strong, and capable of launching animals far in excess of their estimated body weights (Witton and Habib 2010). As someone with a direct hand in this research, it's great to see these ideas being picked up here. Finally, the fact that a children's book is featuring quad launch makes me feel very warm inside, as a generation of people can now grow up with quad-launch in mind whenever they think of pterosaur takeoff. Wait, that's four things, which is one more than a hat-trick, right? Whatever: I don't do football.

Pterosaur Trouble spread, showing Quetzalcoatlus quad launching into awesomeness while shaking off some feathery vermin. Image by D. Loxton and Jim W. W. Smith, provided by M. Cornell

So, in sum...
While I can't claim any great expertise in children's books on prehistory, I've seen enough attempts to bring extinct species to popular audiences to know that I often find more things to dislike than praise. Because it uses up to date science, high quality illustrations and some clever text, Pterosaur Trouble is a fantastic little book that should greatly please and educate any little pterosaurologists you may know. I'll go so far as to say that Pterosaur Trouble is a terrific example of how to make a popular book on prehistoric animals both exciting and scientifically sound, an accolade that is all the more remarkable when you consider that a part of its targeted demographic is still learning to read. As a final recommendation, I could see myself reading a copy of this to my own kids, should I ever have them, without any muttering or wry comments. And if it can please a bitter old thing like me, then it must be doing something right.

If you're after a copy of Pterosaur Trouble, check out the Kids Can Press website, or log onto Amazon. The first book in the series, Ankylosaur Attack, is being published again by Franklin Watts in August, 2013 under ISBN: 9781445119427.

References

  • Currie, P. J. and Jacobsen, A. R. 1995. An azhdarchid pterosaur eaten by a velociraptorine theropod. Canadian Journal of Earth Sciences, 32, 922-925.
  • Frey, E. and Martill, D. M. 1998. Soft tissue preservation in a specimen of Pterodactylus kochi (Wagner) from the Upper Jurassic of Germany. Neuhes Jahrbuch für Geologie und Paläontologie, Abhandlugen, 210, 421-441.
  • Habib, M.B. 2008. Comparative evidence for quadrupedal launch in pterosaurs. Zitteliana, B28, 161-168.
  • 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.
  • Sharov, A. G. 1971. [New flying Mesozoic reptiles from Kazahstan and Kirgizija]. Transactions of the Paleontological Institute, Academy of Sciences, USSR, 130, 104-113. [In Russian]
  • Witton, M. P. 2013. Pterosaurs: Natural History, Evolution, Anatomy. Princeton University Press, 336 pp. In press.
  • Witton, M. P. and Habib, M. B. 2010. On the size and flight diversity of giant pterosaurs, the use of birds as pterosaur analogues and comments on pterosaur flightlessness. PLoS ONE, 5, e13982.
  • Witton, M. P. and Naish, D. 2008. A reappraisal of azhdarchid pterosaur functional morphology and paleoecology. PLoS ONE, 3, e2271.
  • Xu, X., Wang, X. L., and Wu, X. C. 1999. A dromaeosaurid dinosaur with a filamentous integument from the Yixian Formation of China. Nature, 401, 262-266.

Thursday, February 21, 2013

Can you identify this cast?





Some of you may know that I've been trying to track down all manner of 'missing' Solnhofen pterosaurs. All kinds of specimens have been sold off over the years and are in collections all over the world. Many of these are 'known' to curators and visitors, but they don't realise that the material has never been described in the literature and is not readily known to the scientific (or at least pterosaur) community. If any of you do know of pterosaurs languishing in collections that have not been described, do please let me know in the comments.

The flip-side of this, is that things turn up that need to be identified. The other day Matthew Parkes, a curator in Dublin, e-mailed with with this photo. It's a plaster cast of a pterodactyloid pterosaur from the Solnhofen and labeled as being Pterodactylus longicollum (which has only just got a new generic name of Ardeadactylus). This seemes reasonable, the unusually long and tube-like cervical centra of this taxon are visible at the upper left part of this cast and the size and gross proportions are about right (even if few details are visible). However, Matthew wanted to know what original specimen this could be a cast *of* and that's where I'm stuck. I've seen most Ardedactylus specimens and don't recognise it, and I've checked through my extensive collection of photos and papers of all manner of Solnhofen material and can't find a match.

The records in Dublin show that it has been in their catalogue since 1891, so it's at least this old and probably rather older. The catalogue suggest it may be figured as a plate in von Meyer's 1854 Neues Jarbuch paper, but I don't have, and can't find, a copy. Matthew suspects it may be a lost specimen and in which case, this may be the only remainder. Of course if we can work out which it pertains to, we can check at the original institute, but the first step eludes us. So, anyone recognise it? Has it been spotted in Frankfurt or Haarlem? Or is there a figure in some obscure Wellnhofer paper I've missed?

Any help is welcome, and I'm still on the lookout for other Solnhofen pterosaurs, so please let me know of any you've spotted. Thanks and good hunting.

 




Thursday, January 31, 2013

A new Romanian azhdarchid in PLOS ONE

Posted on behalf of Darren:


A new azhdarchid pterosaur – a member of that highly distinctive, long-necked, long-skulled Cretaceous clade most famous for the gigantic Quetzalcoatlus northropi – has just been described by Mátyás Vremir (Transylvanian Museum Society at Cluj-Napoca), Alex Kellner (Museu Nacional in Rio de Janeiro), Darren Naish and Gareth Dyke (both of the University of Southampton). The new animal is from the Upper Cretaceous Sebeş Formation of the Transylvanian Basin in Romania and is named Eurazhdarcho langendorfensis (Vremir et al. 2013). Based on a partial neck and partial right wing found in close association (and hence definitely coming from the same individual), it can be recognised as a new species thanks to various details of its cervical vertebrae.

Speculative reconstruction of Eurazhdarcho langendorfensis 
(in quad launching pose), by Mark Witton.
 Scale bar = 500 mm. From Vremir et al. (2013).

Eurazhdarcho was a small azhdarchid, with an estimated wingspan of about 3 m. As discussed in the paper – and also at theTetrapod Zoology article on the new speciesEurazhdarcho is yet another azhdarchid discovered in a terrestrial, continental sort of environment: it provides more support for the view of azhdarchid behaviour and ecology that Mark Witton and I put forward in 2008 (Witton & Naish 2008). What’s also interesting is that Eurazhdarcho seemingly lived alongside a gigantic species (probably Hatzegopteryx thambema) that would have had a wingspan of 10-11 m. What does this mean for azhdarchid ecology? Does it show that different azhdarchid species were sharing habitats and occupying distinct ecological niches? These issues and more are covered at Tetrapod Zoology and also in the paper. The paper is in PLOS ONE so is freely available to anyone (linked below).

Some geological units reveal evidence of two or even three sympatric azhdarchid species. Diagram produced by Mark Witton and map used with kind permission of Ron Blakey, Colorado Plateau Geosystems, Inc; from Vremir et al. (2013).



Sunday, January 27, 2013

2012 Reach roundup for Pterosaur.net


Well we're well into 2013 now, so time to do a quick summary of the team's contribution to pterosaur research over the last 12 months or so. As usual, there's a good selection of material here covering new species and finds, reviews and summaries, ecology and behaviour and evolutionary studies. I maintain its important in the light of, shall we say, 'competing' sites on pterosaurs, that we show our activity in the scientific literature and the fact that we present our work publicly and put it through peer review (and those who work on pterosaurs will be well aware just how brutal this field in particular can be when it comes to reviews).

As this is a general sort of update post, I thought I'd put up a reminder that the 2013 Flugsaurier meeting in Rio has extended the deadline till the 31st of Jan, so you still have another week to get in your abstracts.On a very different note, I'm appealing for funds to support research into tyrannosaurs (not very pterosaur-y, but very outreach related) so if you can spare a few bucks or just have the time to tweet and blog this, please spread the word.

..............................

Habib M. in press. Constraining the Air Giants: Limits on size in flying animals as an example of constraint-based biomechanical theories of form. Biological Theory: Special Volume (X): XXX-XXX

Habib M. 2012. Mesozoic speed demons: flight performance of anurognathid pterosaurs
2012. ASB Annual Meeting, Gainesville

Hone, D.W.E. 2012. A new specimen of the pterosaur Rhamphorhynchus. Historical Biology, 24: 581-585. (This has been online since 2010 but is only now in print).

Hone, D.W.E. 2012. Pterosaur research: recent advances and a future revolution. Acta Geologica Sinica, 86: 1366-1376.

Hone, D.W.E., Naish, D. & Cuthill, I.C. 2012. Does mutual sexual selection explain the evolution of head crests in pterosaurs and dinosaurs? Lethaia, 45: 139-156.

Hone, D.W.E., Tischlinger, H., Frey, E. & Röper, M. 2012. A new non-pterodactyloid pterosaur from the Late Jurassic of Southern Germany. PLoS ONE, 7: e39312, 18p.

Hone, D.W.E., Tsuhiji, T., Watabe, M. & Tsogbataar, K. 2012. Pterosaurs as a food source for small dromaeosaurs. Palaeogeography, Palaeoclimatology, Palaeoecology, 331: 27-30.

Hyder, E., Witton, M. P. and Martill, D. M. 2012. Evolution of the pterosaur pelvis. Acta Palaeontologica Polonica. [in press]

Naish, D., Simpson, M., & Dyke, G.J. 2012. A small-bodied azhdarchoid pterosaur from the Isle of Wight (UK): its implications for pterosaur phylogeny, anatomy, diversity and distribution. SVPCA (Oxford).

Knell, R., Naish, D., Tompkins, J.L. & Hone, D.W.E. 2012. Sexual selection in prehistoric animals: detection and implications. Trends in Ecology and Evolution, in press. (Not directly pterosaurian, but they do get a big mention and it includes an illustration by Mark too).

Lü, J-C. & Hone, D.W.E. 2012. A new Chinese anurognathid pterosaur and the evolution of pterosaurian tail lengths. Acta Geologica Sinica, 86: 1317-1325.

Martill, D. M., Sweetman, S. and Witton, M. P. 2012. Pterosaurs of the Wealden. Palaeontological Association Field Guide to Wealden fossils.

Steel, L. 2012. The pterosaur collections at the Natural History Museum, London, UK: an overview and list of specimens, with description of recent curatorial developments. Acta Geologica Sinica, 86: 1340-1355.

Witton, M. P. 2012. New insights into the skull of Istiodactylus latidens (Ornithocheiroidea, Pterodactyloidea). PLoS ONE, 7, e33170.



Wednesday, January 2, 2013

Guest Post. Dragon Tails: What Pterosaurs Teach Us about Velociraptor


As part of the flurry of new papers in the Flugsaurier 2012 paper pseudo-volume, Scott Persons has a paper out looking at the remarkable convergences between various dromaeosaurs and a number of rhamphorhynchoid pterosaurs. Here in a guest piece he takes us over this project. - Dave.

An Unexpected Tail
Last week, like a growing 149 million dollars’ worth of other holiday movie goers, I took three hours out of my yuletide respite to make an epic trek across sidewalks long and public transportation foul to my local cinema and saw “The Hobbit: An Unexpected Journey”. I was particularly keen to see how the special effects wizards of Weta Workshop would depict the story’s big bad: Smaug, the dragon. Naturally, since The Hobbit has been broken up into a trilogy, Peter Jackson decided not to fully unveil Smaug, and I’ll have to wait until the sequel. But there was a surprise appearance by a Megaloceros (the “broad antlered” or “Irish Elk”), and Jackson did give the audience a dragon teaser. We got to see a smoke-obscured silhouette here, a clawed foot there, and . . . the tail. 
I’m a PhD student of paleontology at the University of Alberta and, with the help of my supervisor Dr. Phil Currie, I’ve dissected, excavated, measured, photographed, and digitally sculpted the tails of many creatures, ancient and modern. To me, Smaug has an interesting tail. Unlike a crocodile or a dragon from the isle of Komodo, he did not drag his tail behind him. Rather, the Tolkienian drake carried it raised above the ground -- a caudal posture that I suspect shows the influence of dinosaur paleontology on the animators. The tail was very flexible and muscular enough to casually toss aside a group of armored castle-defenders and to do collateral damage to the medieval architecture.
Swooping out of the sky, Smaug’s fiery breath and wrecking-ball tail deal a one-two punch to a stone tower.
That brings me to a fun, blatantly whimsical, and entirely inconsequential thought problem: if the monsters of Middle-earth were not spontaneously generated from Uruk-hai pits and human imaginations, but instead were products of biological evolution, what sort of tail would a dragon most likely have? It’s a silly question, but at least twice in the history of our own planet, reptilian beasts have taken on dragon-like form, and both times their tails have followed remarkably convergent evolutionary paths.

Tail of a Revolution
It can be argued that, of all the dinosaurs ever dug, none have been more scientifically important than Deinonychus. Deinonychus is a kind of dromaeosaurid (meaning that it belongs to a group of carnivorous dinosaurs commonly known, because the group includes the iconic Velociraptor, as “raptors”).  The 1969 study of Deinonychus by Professor John Ostrom documented a wealth of anatomical features previously unseen, or at least unrecognized, in any other dinosaur. Many of these features seemed to imply a high metabolic rate, an active lifestyle, and an ancestral relationship with modern birds. Deinonychus was the catalyst that began the “dinosaur renaissance” or “dinosaur revolution” (a paleontological paradigm shift that has affected how we think about, and approach learning about, a great deal more of prehistory than just dinosaurs -- including pterosaurs). Among the unusual anatomy of Deinonychus was its tail.
The skeleton of a tail is an extension of the spinal column and, in a dinosaur, the tail skeleton is composed of three major kinds of bones. First and foremost, are the interlocking vertebrae, which protect the spinal nerves and sport upwards-projecting neural spines, to which epaxial muscles attach. Then, there are the caudal ribs (or simply “transverse processes” – there is controversy over the proper terminology), which fuse to the vertebrae and project outwards (perpendicular to the long axis of the tail) and also provided anchorage for tail muscles. Last, but certainly not least, are the chevrons. Despite the fact, or perhaps a little bit because of the fact, that these tail bones have received little descriptive or collecting priority from other researchers, I positively love chevrons. They are elegantly shaped, usually resembling capital Y’s, are important for tail muscle function, and (contrary to historic assumption) are useful in identifying taxonomic and evolutionary relationships.  In the tails of both dinosaurs and pterosaurs, chevrons are positioned in between sequential pairs of vertebrae and project downwards.
The basic parts of the tail skeleton shown on a duckbilled dinosaur.
At the start, the tail skeleton of Deinonychus appears normal. Just past the hips, the neural spines, caudal ribs, and chevrons all have a typical shape and they all project to a respectable extent. But, as the tail progresses towards the tip (and it doesn’t take long) things start to get weird. The neural spines, caudal ribs, and chevrons all shrink in, with the former two disappearing entirely . . . and then come the caudal rods. Both the vertebrae and chevrons abruptly develop pairs of elongated rods of bone that project towards the hips. These rods are slender, but very long (the longest easily overlap seven other sequential vertebrae), and they split, each becoming two still thinner rods. Together, rods of the vertebrae form a quiver that virtually encapsulates the dorsal (upper) portion of the tail, and together the rods of the chevrons do the same to the ventral (lower) portion.
Raptor tails are strange! Elongated vertebral rods form an upper quiver and elongated chevron rods form a lower quiver. Skeletal image of Velociraptor courtesy of Scott Hartman (www.skeletaldrawing.com
  Professor Ostrom was rightfully impressed by the caudal rods of Deinonychus, and he realized that such unusual structures must have evolved to serve some sort of unusual function. Ostrom’s best specimens of Deinonychus were preserved lying on their sides and their tails were straight as boards. Ostrom was also much taken with what he thought was the overall highly-athletic nature of the hindlimbs of Deinonychus, so he speculated that the caudal rods were adapted to aid in high-speed pursuit. His idea was that the rods must have stiffened the tail and allowed it to function like the balancing pole of a tightrope walker. This balancing tail, he reasoned, would have come in handy when turning while running or when leaping onto the back of some poor dinosaurian herbivore.

Enter the Sky Dragons
The tail of Deinonychus and its raptor relatives is bizarre, but it is not (as Professor Ostrom himself realized) unique. Among all known vertebrates, a similar tail anatomy has evolved in one other group. . . and now we come to why I have been allowed to spend so much time discussing dinosaurs on what is supposed to be a blog about pterosaurs.
While later and more advanced pterosaurs (like Pterodactylus) only had short, stubby tails, early pterosaurs had long ones. The caudal skeletons of these long-tailed pterosaurs (with the exceptions of the dimorphodontids and very primitive forms) are strikingly similar to that of Deinonychus. In the case of long-tailed pterosaurs, the function of the caudal rods has always seemed obvious. As flying animals, increased rigidity would have helped a tail to serve as a stabilizer or as a rudder.

Look familiar?  The tails of pterosaurs and dromaeosaurids are so similar that, in the fossil-forging black-markets of China, the tail of one is often used to “complete” a partial skeleton of the other. Skeletal image of Rhamphorhynchus courtesy of Scott Hartman (www.skeletaldrawing.com).
In Professor Ostrum’s description of Deinonychus, he expressed his interest in considering this striking example of convergent evolution in a later study. Regrettably, however, he never got around to it -- after all, he soon had a revolution on his hands.

Fleshing Out the Evidence
            A lot has changed since the dinosaur renaissance. For instance, we now know that caudal rods are characteristics of all dromaeosaurids (except the South American unenlagiine dromaeosaurids, which are odd-ducks in many regards). We know a lot more about the evolutionary history of caudal rods, in both dromaeosaurids and pterosaurs. We also know that the rods were not as stiff as Ostrom had thought. Consider the below images of a tail of a Bambiraptor and of a Velociraptor. Both are dromaeosaurids with caudal-rod bearing tails and both are fully articulated. Yet, both are preserved in a sinuous curve (or in the case of the Velociraptor, many sinuous curves).
The strongly curved tail of Bambiraptor.

Despite its caudal rods, this Velociraptor tail is preserved in a graceful S-shaped curve.
So, it turns out that caudal rods are flexible (not surprising when you think about how thin each rod was). But, if caudal rods permitted their tails to curve to such a degree, what good were they? Well, I suspect that the rods were very helpful in keeping the tails rigid. No, I am not talking in circles, and I don’t think that I am talking nonsense. The rigidity provided by the rods of dromaeosaurids was one-dimensional. I have been able to see a lot of dromaeosaurid tail fossils, and many specimens, like the two above, are curved laterally, but I have never seen one that shows articulated caudal rods bending strongly dorsoventrally (that is, up or down).
            That caudal rods provide mostly dorsoventral rigidity makes sense, if you consider the way the rods are arranged in their quivers. The rods are not haphazardly piled on top of one another; rather, they are tightly pressed against the vertebrae and chevrons and are neatly stacked vertically. In other words, the quivers were arranged to be thicker dorsoventrally than they were laterally.
Cross-section through the tail of Deinonychus showing the arrangement of the caudal rods. The arrangement of the rods made the tail harder to bend up-and-down than side-to-side.
A cylindrical tight-rope walker’s pole is the wrong analogue. Instead think of a meter stick, which may be bent with moderate force, but only perpendicular to its broadest plane.
It is now also possible to think a step further and consider the muscles of the tail. Let’s first try to do that in very general qualitative terms. Remember the quickly reduced neural spines, caudal ribs, and chevrons? Those all indicate that the caudal muscles of both dromaeosaurids and pterosaurs were substantially reduced.
To help consider the problem quantitatively, a technique I used was to create digital models of the tail skeleton of a Velociraptor and a Rhamphorhynchus (a pterosaur) and to sculpt the corresponding muscles over the skeletal models. The results of this modeling concur with the qualitative inference. In particular, raptors and pterosaurs were found to have very weak caudofemoral muscles (indeed, some pterosaurs may not have had caudofemoral muscles at all).

Digital reconstructions of the tail of Velociraptor, showing the tail and hip skeleton (A), the caudofemoral muscles (B), and the full muscle reconstruction (C).
Digital reconstructions of the tail of Rhamphorhynchus, showing the tail and hip skeleton (A), the caudofemoral muscles (B), and the full muscle reconstruction (C)
 These caudofemoral muscles merit special explanation. They are muscles found in the tails of reptiles and dinosaurs that are actually part of the hind limb system. They are the primary limb retractors and provide a major power boost when walking and running.
Again, these adaptations seem easy to explain in the tail of pterosaurs. If a tail is to serve as an inflight rudder, some lateral flexibility would be needed, but strong dorsoventral stiffness would have prevented the constant pull of gravity from deflecting the tail downwards and disrupting the body’s aerodynamic form, and all the better if this stiffness was obtained by the passive rigidity of bone, rather than the hard work of muscle. Reducing weight is always a benefit for flight, and, perhaps, particularly reducing posterior weight. What better posterior weight could a flying animal lose than that of a tail muscle whose primary function is in land-bound locomotion?
Thanks in large part to the work of pterosaur researcher Dr. Dalla Vecchia, we know that among the most primitive of pterosaurs (animals like Austriadactylus and Eudimorphodon) caudal rods had not yet evolved (though there are some anatomical signs that they were in the works). However, all these primitive forms already had clear possession of the power of flight. We can be certain (or about as certain as the fossil record ever permits) that, when the caudal rods of pterosaurs evolved, it was in the context of an aerial lifestyle.
To me the remarkable similarity in form between the tail skeletons and muscles of pterosaurs and dromaeosaurids indicates an equally strong similarity in function.  Is it possible then, that the tails of dromaeosaurids also evolved on the wing?

Feathered Dragons from the Orient
The little dromaeosaurid Microraptor has sparked something of its own dinosaur revolution. Microraptor is among the oldest and most primitive of the known dromaeosaurids. Buried in fine volcanic ash, specimens from the famous fossil beds of China have revealed that Microraptor had feathered wings on the fore and (oddly enough) on the hind limbs. It also had caudal rods. Whether or not Microraptor could truly fly or simply glide is a matter of current scientific debate, but the winged-raptor was clearly not a land-bound creature.


Microraptor has wings and caudal rods.
An older Chinese dinosaur, Anchiornis is a primitive member of the Deinonychosauria. Named in honor of Deinonychus, the group Deinonychosauria includes the dromaeosaurid and their close relatives the troodontids. Like Microraptor, Anchiornis had wings, but it lacked caudal rods. Thus, as with pterosaurs, it appears possible to bracket the evolution of the bizarre dromaeosaurid tail between two aerial genera.
Anchiornis has wings but not caudal rods.
Does all this mean that the tails of Deinonychus and Velociraptor indicate that these dinosaurs could fly? Certainty not. However, I do think it means that we should think of Deinonychus, Velociraptor, and other dromaeosaurids like Cretaceous ostriches. They are animals without the ability to fly or glide but who have inherited a few telltale anatomical feature that attest to their ancestor’s aerial life. (I am certainty not the first person to suggest this. Based on various other lines of anatomical evidence, many paleontologist, most prominently Greg Paul, have argued that dromaeosaurids were secondarily flightless.)
I also think it means that, when you imagine a flying dragon, be it a dinosaur, pterosaur, or thought problem fantasy, you should not envision it with a tail that limply streams behind it. The tail should be, most probably, held up; be capable of lateral, but not vertical, swishes; be muscularly reduced and light weight; be quite elegant and graceful; and, thus, not (I am afraid, Mr. Jackson) be of much use as a siege weapon.