May 30, 2013 | 40
I love academic conferences, I love pterosaurs, and I love South America. So, as predicted, I very much enjoyed the International Symposium on Pterosaurs I just attended: it was the sixth symposium devoted specifically to pterosaurs, and was held at the Museu Nacional/UFRJ (= Universidade Federal do Rio de Janeiro), Rio de Janeiro. Yes, an academic conference held in Rio.
It was great and an enormous quantity of new and exciting information on pterosaurs was discussed and presented. There was also the chance to see many key Brazilian specimens. The conference ended with a field trip to Araripe – discovery site of many of these often spectacular Cretaceous pterosaur fossils – but I was unfortunately unable to attend due to the usual constraints of personal life. Indeed, economic conditions meant that many of our colleagues from Europe, North America and elsewhere didn’t make it to the meeting (though I know that some people from the USA failed to make it because they didn’t get their visas sorted out in time). Anyway, enough preamble…
Reproduction, ontogeny, nests, eggs, and babies
We held several roundtable discussions during the meeting and in fact the conference began with a discussion of ontogeny and reproduction co-presented by myself, David Unwin and Chris Bennett. Dave Unwin discussed what we know about pterosaur eggs and embryos and how existing data (from Darwinopterus, Pterodaustro and so on) seemingly shows that pterosaurs produced proportionally small eggs and precocial juveniles that were ready to fly at or shortly after hatching (see links below for more on this subject: it has been covered at length in previous Tet Zoo articles).
I reviewed reproductive behaviour in extant reptiles in order to give some idea of what might be applicable for pterosaurs. There are many caveats attached to the phylogenetic bracketing approach, and uncertainties about the affinities of pterosaurs also mean that what we see in extant crown-archosaurs may not apply to pterosaurs. Nevertheless, nest building, nest-guarding, post-hatching parental care and other behaviours are still on the cards for pterosaurs, even if they aren’t crown-archosaurs.
Chris Bennett looked at pterosaur ontogeny and growth rates. The continuing absence of small Pteranodon specimens remains an interesting conundrum and – Chris argues – it strongly suggests that juvenile Pteranodon individuals were not precocial and were not doing the same sort of thing as adults. It seems logical to think that pterosaurs were not uniform in such things as growth style and reproductive ecology: precociality in, say, Pterodactylus does not demonstrate such in Pteranodon, but we really need more evidence before we can go any further with this. Prondvai et al. (2012) recently argued that Rhamphorhynchus was altricial, but it was suggested in the discussion that this conclusion failed to take notice of Bennett’s (1996) evidence for annual growth stages in this taxon.
The second roundtable discussion (it happened on the next day: I’m not discussing things in chronological order) was devoted to systematics and phylogeny. Brian Andres reviewed his thoughts on where we’re at with respect to our understanding of pterosaur phylogeny (he also gave a separate talk on “How I learned to stop worrying and love the cladogram”). He has a “facepalm” attitude to statements from some of us (like, err, me) that pterosaur phylogeny is under-studied and poorly resolved (I remain dissatisfied with the fact that hypotheses of pterosaur phylogeny are based on data sets of 100-120 characters or less), and indeed argued that even conflicting phylogenies (e.g., Kellner 2003 vs Unwin 2003) are significantly similar (76.4% the same, in this specific case). Brian’s primary take-home was that things aren’t that bad, and that our phylogenies are getting more similar to one another over time.
In the same roundtable session, Fabio Dalla Vecchia reviewed our knowledge of Triassic pterosaur phylogeny. Often forgotten is that some specimens of the Triassic taxa demonstrate – if correctly identified – profound changes in cranial ontogeny. A juvenile Austriadactylus, for example, essentially lacks the prominent cranial crest present in an adult and looks more like the (apparently distantly related) Preondactylus. Taissa Rodrigues also discussed taxonomy and systematics. In the following discussion, we covered ranked nomenclature (and why it should be abolished), species concepts and the debate over binomials and uninomials. None of this is specific to pterosaurs, but (in my opinion) the more people move away from ranked classification and toward tree-based thinking, the better.
Artwork and museum visits
We were constantly surrounded by pterosaur-themed artwork and sculpture during the meeting. Several displays were devoted to the work of Maurilio Oliveira, Paulo Márcio Esper and Sergey Krasovskiy, and Helder da Rocha’s excellent model skeletons were a major, unmissable feature of the event. As explained in his talk, Helder made a foam model of the skeleton of Guidraco (just for fun) one day. It was (he happily admits) substantially inaccurate, with many parts modelled on those of other pterosaur species (this explains the moniker ‘The Imaginary Pterosaur’, used as his blog title). He developed a technique (it uses sheets of white foam, stuck together with glue, burnt with a lighter to create a realistic, bone-like texture) and began to create better, more accurate skeletons, even the largest of which – like the Tupuxuara shown here – weigh less than 1 kg.
These models are so good that I initially assumed that I was looking at professionally done resin casts. I assume it’s only a matter of time before Helder is selling these models to museums for display: they look great and are close to being absolutely accurate. Helder also designed the excellent conference t-shirt.
On the subject of mounted skeletons and so on, we got to spend appropriate time in the Museu Nacional, located in the middle of the beautiful Quinta da Boa Vista park. The Mesozoic gallery here is spectacular, featuring mounted skeletons of the sauropod Maxakalisaurus, the pterosaurs Tupandactylus and Tropeognathus, and life-sized models of the dyrosaurid crocodyliform Guarinisuchus and sauropodomorph Unaysaurus. A spectacular full-sized skeleton of the spinosaurid Angaturama (or… is that Irritator?) is posed with an Anhanguera in its jaws (a reconstruction based on an actual fossil), and the holotype of another spinosaurid – Oxalaia – is also on display, as is much else besides. Nearby are mounted skeletons of Smilodon and the sloths Eremotherium and Glossotherium (sadly, the awesome phorusrhacid Paraphysornis was not on display at the time of our visit). It was remarkable to see so many recently described, recently named specimens in close proximity.
On another day, we visited another institution: the Museu de Ciências da Terra (or Museum of Earth Sciences). Again, a spectacular assortment of fossil taxa were seen, including the Tupandactylus imperator holotype, and mounted skeletons of the enormous dicynodont Dinodontosaurus and rauisuchian Prestosuchus. I was especially thrilled to see the actual skull of the incredible ‘sabre-toothed’ sebecosuchian Baurusuchus pachecoi and the absurdly robust, complete skeleton of a big hyperodapedontine rhynchosaur labelled Scaphonyx fischeri (that name’s a nomen dubium and I’m not sure about the exact status of the specimen I was looking at).
On non-pterodactyloid pterosaurs
Back to the conference, non-pterodactyloid pterosaurs formed the focus of a few talks and posters. Marina Soares and colleagues had a poster on the alleged Upper Triassic pterosaur Faxinalipterus minima, a poorly understood (and obscure) reptile known from a collection of limb bones, none of which look especially pterosaur-like. Indeed, their reanalysis showed that the specimen lacks pterosaur characters, and its bones are no more pterosaur-like than are those of dinosaurs, croc-line archosaurs, or protorosaurs.
Niels Bonde discussed new data on cranial pneumaticity in the same Rhamphorhynchus specimen he and Per Christiansen previously discussed in 2003 (Bonde & Christiansen 2003). Fabiana Costa (and colleagues) presented data on a ‘new’ anurognathid specimen (actually preserved on the same slab as a Sordes specimen) that seemingly preserves evidence for a long tail… or, a tail longer than that expected for an anurognathid anyway. The idea that at least some members of this group were longer-tailed than usually thought has been kicking around for a while now though convincing demonstration of this has yet to be properly documented.
Xin Cheng and colleagues presented data on another new wukongopterid taxon and Dave Unwin discussed new specimens of Darwinopterus and what they tell us about ontogenetic transformation in this taxon. What’s especially intriguing about these specimens is that they suggest that various ‘typical’ pterodactyloid traits (like a proportionally short tail, elongate metacarpus and so on) might have evolved via heterochrony. I was very pleased to hear this (err, even though I heard it previously at one of the SVPCA meetings), since I was also planning to touch on the same concept in my talk on Vectidraco (the latter seems to be skeletally mature, yet possesses characters that – elsewhere within pterosaur phylogeny – are expressed most usually in juveniles). Anyway, Darwinopterus continues to provide copious key information on pterosaur biology and ontogeny.
Incidentally, those claims that pterosaurs exhibit obvious isometry across ontogeny (that is, they stay the same in form and proportions but merely get bigger) are not accurate, and some of the key specimens linked to this claim (cough cough Ptweety cough cough) do not represent what their champions think they do.
Wings and pterosaur affinities
Chris Bennett gave two presentations, one on pterosaur wing anatomy and one on the character support used to link pterosaurs to other archosauromorphs. In the former talk, Chris explained how detailed re-examination of the Zittel wing (using high resolution photographic mapping) provides new data on the form and distribution of actinofibrils and of the retrophalangeal wedge (a band of tissue that borders the posterior edges of the wing phalanges, streamlining them into the wing tissues). If Chris is right, some previous interpretations of pterosaur wing tissue structure are significantly inaccurate: actinofibrils, for example, are not widely spaced, rod-like structures on the patagial underside, but lenticular, closely spaced objects embedded within the dorsal dermis.
In the second talk, he looked in detail at several characters purported to link pterosaurs to crown-archosaurs, in particular addressing Nesbitt & Hone’s (2010) paper in which they reported external mandibular fenestrae, antorbital fossae and possible fourth trochanter homologues in assorted early pterosaurs. Chris did a pretty convincing job of showing that at least some of these observations are erroneous. The ‘consensus view’ on pterosaurs is that they’re crown-archosaurs, close to dinosauromorphs (remember that Ornithodira exists no matter where pterosaurs go on the cladogram: it’s the name for the pterosaur + dinosaur node and does not require that they’re more closely related to one another than they are to other reptiles). Chris has argued that pterosaurs actually belong elsewhere within Archosauriformes: this point of view isn’t popular but the debate is certainly not over yet.
Rachel Frigot presented her work (done with Colin Palmer) on pterosaur trabeculae. It seems that – contrary to expectations – the trabeculae do not act to prevent distortion of the wing elements when they’re placed under load. Intriguingly, trabeculae seem to be located ‘around’ pneumatic spaces in the long bones, suggesting that they might be useful as osteological correlates of the extent of the skeletal pneumatic system.
The vast majority of talks (and posters) covered new pterodactyloid taxa and various aspects of pterodactyloid anatomy and systematics. Brian Andres spoke (on behalf of co-authors) about a new Late Jurassic pterodactyloid from the Shishugou Formation of Xinjiang, China. This unit has previously yielded the large rhamphorhynchid Sericipterus, and Lower Cretaceous sediments nearby yield abundant specimens of Dsungaripterus (as well as the somewhat doubtful taxon Lonchognathosaurus). Sericipterus is a robust animal that might have been a scavenger or predator of terrestrial environments. The new pterodactyloid from the Shishugou is important in that it appears intermediate in metacarpal elongation and other characters between non-pterodactyloids and later Late Jurassic pterodactyloids.
Laura Codorniú gave two talks on pterosaur braincase anatomy: one on a new Jurassic species from Argentina, and another on Pterodaustro. Both talks included enormous amounts of new anatomical information. Fabio Dalla Vecchia covered his fascinating forensic-style investigation of a spectacular, near-complete pterodactyloid skeleton, exhibited by the CosmoCaixa Science Museum in Spain and identified as that of an Anhanguera piscator. The skeleton proved to be a composite incorporating numerous reconstructed or fabricated parts.
Shunxing Jiang spoke about a new boreopterid specimen argued to represent a new species of Boreopterus. Boreopterids (discussed previously on Tet Zoo: see links below) are very interesting and I find their elongate, slender teeth highly intriguing. Were they using them to grab (or ‘cage’, or filter?) some specific prey type? They seem to be closely related to ornithocheirids, though whether all species currently included within the group really belong there remains somewhat controversial. There were quite a few poster presentations on Anhanguera-type animals (it’s currently down to opinion whether you term these animals anhanguerids or ornithocheirids): anybody really interested needs to get hold of the abstract volume.
Here I will mention the third roundtable discussion. It was titled ‘New techniques for pterosaur studies’ and involved presentations on phylogenetic methods and CT-scanning. The discussion we had afterwards ended up focusing on the open access movement, copyright law and the sharing of pdfs (how quaint that some publishing companies tell authors not to send out more than 20 digital copies of their own papers). Blogging was also discussed. In a surprise move, Taissa asked me about the giraffe flotation paper I co-authored with Don Henderson (Henderson & Naish 2010). Funnily enough, the technique used in that paper has already been applied to pterosaurs since I know that Don and Dave Hone have a manuscript in the system on the flotation behaviour of pterosaurs.
We’re all here for the azhdarchoids
Several talks were devoted to azhdarchoids, the most interesting of pterosaurs (in my highly subjective and personal opinion). In the phylogenetic scheme that I (and some of my colleagues) prefer, the typically short-snouted tapejarids are outside of the clade that includes the larger, longer-snouted thalassodromids and azhdarchids (the name Neoazhdarchia can be applied to the thalassodromid + azhdarchid clade) (Unwin 2003). Chaoyangopterids may be part of Neoazhdarchia as well. However, there are currently several competing views on the phylogeny of these lineages (e.g., Unwin 2003, Kellner 2004, Lü et al. 2008, Martill & Naish 2006, Andres & Ji 2008, Pinheiro et al. 2011) and many of my South American colleagues prefer the hypothesis that thalassodromids (and maybe chaoyangopterids too) are a sub-clade of Tapejaridae. In the discussion here, note that the term tapejarid refers only to tapejarids in the strictest sense (as per Martill & Naish 2006): it does not include Tupuxuara and kin.
Bruno Vila Nova spoke about tapejarid cervical vertebrae, Felipe Pinheiro and colleagues presented a poster on the possibility of cranial kinesis in tapejarids, and Taissa Rodrigues (on behalf of co-authors) discussed post-cranial morphology in thalassodromids. Lots of useful and interesting data on cervical vertebrae in these talks.
I spoke about Vectidraco, with diversions on the political geography and anthropology of the Isle of Wight and on postcranial skeletal pneumaticity. Some of this is supplementary to the data included in Naish et al. (2013) and needs to be published at some stage (though probably not the stuff on the political geography and anthropology of the Isle of Wight, ha ha).
Fabiana Costa discussed the idea that two elongate cervical vertebrae from the Upper Jurassic of Tendaguru might belong to Azhdarchidae. This idea has been batted backwards and forwards over the years; the competing (published) hypothesis is that the vertebrae belong to ctenochasmatids of some sort (Andres & Ji 2008). The latter possibility looks more likely in view of the Late Jurassic age of the specimens, but – as is so often the case with fragmentary specimens – we need better fossils before we can be more confident about this sort of material. Given that I’ve previously identified azhdarchid material that dates to the very earliest part of the Cretaceous (see Dyke et al. (2011) and image below), I’m not sure that Late Jurassic azhdarchids would be quite as problematic as some other workers do.
Nathan Carroll discussed new azhdarchid material from the Two Medicine Formation of Montana. The animal concerned – represented by vertebrae, pelvic elements and parts of the fore- and hindlimbs – seems to belong to a new taxon, in which case the Two Medicine Formation includes this one in addition to both Montanazhdarcho and the unnamed azhdarchid described by Padian (1984).
Several aspects of this research are especially interesting to me. Firstly, the presence of several apparently contemporaneous azhdarchid taxa led Nathan to propose that these animals were practising niche partitioning of some sort. If your memory is good, you will recall that I and my colleagues referred to the same idea in our paper on the Romanian azhdarchid Eurazhdarcho, published earlier this year (Vremir et al. 2013). Secondly, the Two Medicine material possesses several anatomical features which seem to be pretty good indicators of strong terrestrial behaviour in this animal – needless to say, this stuff nicely vibes with what Mark Witton and me said in our 2008 paper on azhdarchid palaeobiology (Witton & Naish 2008).
Thirdly, Nathan finished his talk with a slide that showed the remarkable life-sized azhdarchid puppet he has created. A person fits inside it and it has both fairly realistic proportions and ranges of movement. Initial plans were to bring it down to Rio for the meeting… unfortunately, that didn’t work out. I really hope to see the puppet in person one day. Surely it’s only a matter of time.
And so things drew to a close. I and several others spent time after the meeting looking at Brazilian pterosaur fossils, and – as I said above – there was also a fieldtrip. A volume of extended abstracts was produced for the meeting and is a definite must-have for those with a keen interest in the Pterosauria (I myself have a huge pile of spare copies, though most are reserved for colleagues in the UK). A volume of collected papers resulting from the meeting will be published in Historical Biology. The next meeting? As explained by Dave Unwin, this will be held in 2015 at the University of Portsmouth, UK (my former academic home).
Despite the no-showing of several colleagues who were supposed to be in attendance, the Rio pterosaur symposium of 2013 was a great success and an enormous quantity of novel and interesting information on pterosaurs was presented. I owe a huge debt of thanks to Alex Kellner, Taissa Rodrigues and everyone else involved in the meeting. Thanks to Juliana Sayão, Fabiana Costa, Renan Bantim and everyone else who assisted in the organisation and chairing of the meeting, and well done and thanks to Helder da Rocha and others for providing artwork, replicas, designing the t-shirt and so on. Thanks to Lilian Alves for her time and assistance in the collections of the Museu Nacional, and thanks too to Nate, Ash, Dave, Chris, Brian and others for their help with specimens, insight and opinions. Thanks especially to Nate and Ash for hilarious stories about their adventures on the subway.
And, if you’re wondering, while in the beautiful city of Rio I saw (and photographed) an enormous number of bird species that were totally new to me. When time allows, I’ll be writing about them here as well.
For previous Tet Zoo article on pterosaurs, see…
Refs – -
Andres, B. & Ji, Q. 2008. A new pterosaur from the Liaoning Province of China, the phylogeny of Pterodactyloidea, and convergence in their cervical vertebrate. Palaeontology 51, 453-469.
Bennett, S. C. 1996. Year-classes of pterosaurs from the Solnhofen Limestone of Germany: taxonomic and systematic implications. Journal of Vertebrate Paleontology 16, 432-444.
Bonde, N. & Christiansen, P. 2003. The detailed anatomy of Rhamphorhynchus: axial pneumaticity and its implications. In Buffetaut, E. & Mazin, J.-M. (eds) Evolution and Palaeobiology of Pterosaurs. Geological Society Special Publication 217. The Geological Society of London, pp. 217-232.
Kellner, A. W. A. 2003. Pterosaur phylogeny and comments on the evolutionary history of the group. In Buffetaut, E. & Mazin, J.-M. (eds) Evolution and Palaeobiology of Pterosaurs. Geological Society Special Publication 217. The Geological Society of London, pp. 105-137.
- . 2004. New information on the Tapejaridae (Pterosauria, Pterodactyloidea) and discussion of the relationships of this clade. Ameghiniana 41, 521-534.
Lü, J., Unwin, D. M., Xu, L. & Zhang, X. 2008. A new azhdarchoid pterosaur from the Lower Cretaceous of China and its implications for pterosaur phylogeny and evolution. Naturwissenschaften 95, 891-897.
Naish, D., Simpson, M. I. & Dyke, G. J. 2013. A new small-bodied azhdarchoid pterosaur from the Lower Cretaceous of England and its implications for pterosaur anatomy, diversity and phylogeny. PLoS ONE 8(3): e58451. doi:10.1371/journal.pone.0058451
Nesbitt, S. J. & Hone, D. W. E. 2010. An external mandibular fenestra and other archosauriform characters in basal pterosaurs. Palaeodiversity 3, 225-233.
Padian, K. 1984. A large pterodactyloid pterosaur from the Two Medicine Formation (Campanian) of Montana. Journal of Vertebrate Paleontology 4, 516-524.
Pinheiro, F. L., Fortier, D. C., Schultz, C. L., de Andrade, J. A. F. G. & Bantim, R. A. M. 2011. New information on the pterosaur Tupandactylus imperator, with comments on the relationships of Tapejaridae. Acta Palaeontologica Polonica 56, 567-580.
Prondvai, E., Stein, K., Ősi, A. & Sander, M. P. 2012. Life history of Rhamphorhynchus inferred from bone histology and the diversity of pterosaurian growth strategies. PLoS ONE 7(2): e31392. doi:10.1371/journal.pone.0031392
Unwin, D. M. 2003. On the phylogeny and evolutionary history of pterosaurs. In Buffetaut, E. & Mazin, J.-M. (eds) Evolution and Palaeobiology of Pterosaurs. Geological Society Special Publication 217. The Geological Society of London, pp. 139-190.
Vremir, M., Kellner, A. W. A., Naish. D. & Dyke, G. J. 2013. A new azhdarchid pterosaur from the Late Cretaceous of the Transylvanian Basin, Romania: implications for azhdarchid diversity and distribution. PLoS ONE 8(1): e54268. doi:10.1371/journal.pone.0054268