At the end of my last post I raised a most significant point – Bellubrunnus isn’t a Solnhofen pterosaur. While it’s easy to think that those Jurassic lithographic beds from Bavaria are the Solnhofen, it’s not the case. Like all rock records, different divisions are known and are grouped in various hierarchical clusters. The Solnhofen is home to a lot of important species (Archaeopteryx for starters, not to mention all the pterosaurs and insects and plants and fishes) and a good deal of work has gone into working out the stratigraphy of all these different fossil-bearing beads, but not all lithographic limestones lie in the Solnhofen.
Obviously this doesn’t mean that an animal from one layer right above or below the Solnhofen didn’t overlap in time with other strata – the rocks don’t delineate when and where species lived. However, Brunn is rather older than even the oldest Solnhofen beds and from the Kimmeridgian rather than the Tithonian. While the rocks are of a similar kind and were put down in a similar manner in similar ecosystems, the two are different.
Work on the Brunn beds are still very new and I must confess I’ve not looked into it in any great detail (not least as all the literature seems to be in German) and have had to rely heavily on my colleagues here. Still, the two do seem to contain different taxa as a whole and while to date the higher vertebrates at Brunn have been few and far between, given the quality of the preservation, I don’t think there’s any reason to expect that we won’t get a lot more in the future. Moreover this does suggest that Brunn is different to the Solnhofen and so we might expect a different (if closely related) fauna to be present. In short, the fact that we now have literally hundreds of pterosaurs from the Solnhofen and no record of Bellubrunnus there, supports the idea that this is a different genus, and also the idea that there might be many more new pterosaur species in there to be found. At the very least, there is a lot more to learn from the Brunn biota.
One last point to address here lies in the temporal distribution of rhamphorhycnhines. The recently described Qinlongopterus is also known from a single, small, and young specimen, though it heralds from the Middle Jurassic of China. As described this taxon is really rather similar to Rhamphorhynchus and it was suggested that as such, the rhamphorhycnhines might be really rather stable as a group and went long periods of time with little morphological change. Obviously Bellubrunnus interrupts this apparent trend, as compared to the Middle Jurassic of China, it’s much closer in time and space to Rhamphoprhynchus, yet does have quite a few differences. This is probably due to that fact that unlike Bellubrunnus, Qinlongopterus is really badly preserved, and morphological information is rather limited. What can be seen in Qinlongopterus is very Rhamphorhynchus-like, but that’s not saying much since the condition of it means that not all the many details can be seen. Plus of course the young of species tend to be much harder to tell apart than the adults, since, well they don’t have all their adult features yet and typically the younger they are the harder that will be. So in fact this ‘stability’ is illusory based on the age and condition of Qinlongopterus and in any case is interrupted by the emergence of Bellubrunnus and its differing anatomy.
And on that subject, next up, that interesting tail…