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.

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.

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!

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 Booth, Julia 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):