Wednesday, October 23, 2013

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.