Archive for July, 2012



Bellubrunnus – definition, diagnosis, and why it’s not Rhamphorhynchus

Right, lets crack straight on with dealing with the details of this lovely little thing. First off, if you have read this post on pterosaur ontogeny, you should be able to recognise that while Bellubrunnus is small (in fact it’s tiny, with a wingspan under 30 cm and a skull just a fraction over 2 cm), it’s also very young. The head is proportionally huge, and the eyes (represented by the sclerotic rings) are massive too, lots of neurocentral sutures are open (as can be seen by displaced centra in the dorsal series) and the wrists, pelvis and scapulocoracoids are unfused, and even the skull is coming apart. Unusually for such a small pterosaur though, the tarsals are well ossified, though they are rather amorphous in shape, which is a classic feature of young pterosaurs.

This then is a very young animal. That does of course complicate issues a little as obviously some things change during growth and we don’t want to misdiagnose this by thinking it has some unique features which are in fact simply a result of its age. On the other hand though, following mostly from the work by Chris Bennett, we have a good idea of the ontogenetic changes undergone by Rhamphorhynchus as it grew so we do know what kinds of things change as they grow (and so can be avoided, or used carefully) and which don’t (and can be used pretty freely).

Lets start with the most obvious thing – Bellubrunnus is a rhamphorhynchoid pterosaur. It has a proportionally small head (compared to the size of the animal as a whole, and the body specifically), short neck, short wrist and pteroid, short metacarpal IV, long tail, long 5th toe and other characteristics. Moreover, it’s also a rhamphorhynchine – a derived member of this basal assemblage and close to things like Rhamphorhynchus and the recently described Qinlongopterus. Bellubrunnus exhibits a number of characters associated with this clade such as the shape of the deltopectoral crest and the proportional length of the wing finger.

Bellubrunnus is also really rather like Rhamphorhynchus which might be no surprise given the rocks it heralds from (though more on this later) – the area is kinda famous for producing specimens this genus in serious numbers. The two share a number of characters previously used to diagnose the latter alone such as edentulous jaw tips, a femur shorter than the humuers, and an H-shaped prepubis. However, the two also have some rather notable differences that clearly mark them as different taxa. Among other things, Bellubrunnus has only 22 teeth (or perhaps even fewer) compared to some 34 in Rhamphorhynchus, it has a rather different tail anatomy (more on this to follow as well) a different humeral shape, and several major proportions of the limbs are quite different.

The point about proportions is quite a significant one. Proportional ratios between various elements are common characters for pterosaur taxonomy and systematics, but unhelpfully, we also know that some of these change during ontogeny in at least some groups. So we do need to be careful and this is no exception. The best example here is the ratio of the humerus to the femur – in Rhamphorhynchus this seems to get larger as the animal gets bigger. Small (and so young) specimens tend to have a lower ratio and adults a high one. Bellubrunnus is among the smallest pterosaurs known and comparable in size to the smallest (and youngest) specimens of Rhamphorhynchus, but it’s ratio is the higher than any specimen of the other genus.

While I’ve not mentioned it here, in the paper we do compare this to other members of the rhamphorhynchine clade and provide similar numbers of difference in things like tooth count, anatomical features, skeletal proportions and the like. A number of these taxa are rather fragmentary and hard to say too much about, but do always differ from Bellubrunnus.

So in short while we can be sure this is a very young animal, we can also be confident with our assignment to the rhamphorhycnhoids and rhamphorhynchines, and while this would appear to be a close relative of Rhamphorhynchus, it’s also clearly quite different in a number of characters, marking it out as a new and distinct taxon. One last point needs to be raised here too as a launch-pad for the next post, Bellubrunnus is from Brunn, and Brunn, well it’s not actually part of the traditional Solnhofen that is home to Rhamphorhynchus. It’s older and the two were not contemporaneous.

Introducing Bellubrunnus

Visitors to the Solnhofen Museum in Germany in recent years might well have seen a delightful specimen of a small Rhamphorhynchus on display. While clearly a nice little find, it was hard to see too much detail under the glass given how a) small it was and b) just how close in colour the bones were to the matrix it was preserved in. Certainly I didn’t give it much more than a glance when I first saw it as part of the Flugsaurier fieldtrip way back in 2007, and I’m not sure that many of my colleagues did either (though to be fair we had only an hour or two to try and do the whole museum, and well, if you work on pterosaurs you generally have seen a lot of Rhamphorhynchus material).

However, while I was in Dublin, a PhD student working on Solnhofen jellyfish pointed me back to this as something worthy of more special interest. Once I had some decent photos of it, it was clear that it was indeed something rather more special than just a young and complete specimen of Rhamphorhynchus. Indeed, while clearly having a lot in common with this very well known genus, there were some obvious and pretty significant differences. Talking to the curator at the Solnhofen, Martin Roeper, I discovered that (perhaps inevitably) Helmut Tischlinger had already taken a number of UV images of the material and he and Dino Frey had planned to work on it, but things had fallen behind. A few more exchanges and I was generously offered the chance to lead the formal description of the material and write up this interesting find.

That paper has now been completed and indeed published, and as such the inconveniently labelled specimen BSP–1993–XVIII–2 should now be known as Bellubrunnus rothgaengeri. The species name honours Monica Rothgaenger who led the team that uncovered the material and donated it to the museum (note that while this has a BSPG number, it is on permanent loan to the Solnhofen). The generic name comes from the locality of the matieral, Brunn, and the Latin ‘bellus’ meaning beautiful. This is the beautiful one from Brunn, and well, as you can hopefully see, it really is a superb specimen. It’s effectively complete and articulated and preserved in ventral view. While it is indeed hard to make out too much detail under normal lighting conditions, under UV, the difference between bone and matrix is obvious in the extreme and the details quite apparent and with tiny and fragile parts like the sclerotic rings, the palate, the tarsals and prepubes being preserved. Sadly though, there’s no sign of a single jot of soft tissues anywhere, despite the superb (indeed, unusually good) preservation of the bones. The matrix around the bones has been prepared right down to help expose them and you can see the scrape marks of preparation tools around the specimen.

Happily for all fans of sci comms and outreachy things, the paper is in PLoS ONE (the latest in quite a series for pterosaur work this year it must be said) and so freely available. There is, inevitably, a lot to be said about this animal and while the paper IS freely available, I think that there is a good mine of interesting things here that help reveal ideas about pterosaur evolution and anatomy. And let’s face it, even with the best will in the world, it can be hard to fight through a long paper, and it’s rather easier to read a few blog posts. That said, obviously with the paper being freely available, if you do want more details and specifics and citations etc. then the paper should be the first place you look.

This post then is perhaps not so much more than a holding pattern while obviously showing off the material itself, and this superb life reconstruction by Matt van Rooijen (which is also in the paper and so available) whom I must thank for his superb efforts. I’m not going to try and spin this out too much, but there are some nice areas of interest about Bellubrunnus that can be easily separated from the rest and make nice short and self-contained posts, so I’ll try and do just that. We’ll start almost immediately with the most obvious question – what exactly is it?

Hone, David W. E., Helmut Tischlinger, Dino Frey & Martin Röper. 2012. A new non-pterodactyloid pterosaur from the Late Jurassic of southern Germany. Public Library of Science ONE.

Just an unnecessary tease

I’ve been hinting off and on for a couple of weeks that I have something significant in the pipes and it’s due out this time tomorrow (assuming the journal sticks to the publication date and time it told me). So I thought I’d be a tease and leave these not-that-cryptic hints about it up in time for tomorrow’s big splash.

Sciurumimus

Readers will remember a beautiful fossil from the Solnhofen being shown on here back in November of last year. People who have access to the internet will probably now now that yesterday the first formal publication on this animal came out. It’s now named Sciurumimus – the squirrel mimic – on account of the rather bushy tail. There’s already a ton of discussion on this online and quite some hefty coverage so I’m not going to dive into the ins and outs of feather distribution in theropods or the phylogenetic position of it. It is worth comparing it to Juraventor of course – sister-taxon to Sciurumimus in the analysis and from the same beds. Despite the obvious gross similarities, the authors do note a ton of small differences between the two that suggest they are genuinely distinct.

Of much more interest to the readers though will be the fact that once more Helmut Tischlinger has been generous enough to send me a variety of nice images with permission to publish them here. At least one of these isn’t in the paper and the res is pretty good so even those of you who’ve been able to peruse the PNAS paper might do well here, so enjoy. As usual my thanks to him for this very generous act and a reminder that these are his images and should not be reproduced without permission etc.

 

 

 

 

Interview with Steve White

Typical isn’t it, you wait six months for a new palaeoart interview and then two come along at once. Today’s entry is Steve White. Steve may not have the profile of some of his colleagues but has produced some beautiful artworks. Most importantly perhaps, he is the editor of a soon-to-be-released book on the palaeoart of dinosaurs and featuring new works and words from an absolute hatful of artists, many of whom have featured here over the years and will no doubt be of great interest. Anyway, back to Steve and his art and as per usual please do not take or reuse these without permission and my thanks to Steve for his generous loan of his work:

Continue reading ‘Interview with Steve White’


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