The name ‘Helmut Tischlinger’ is probably unknown to almost any one who does not work on pterosaurs or in German vertebrate palaeontology, yet he deserves huge recognition for his work, and that work is very important. You have, whether you know it or not, probably seen some of his images at one time or another and if so were probably struck more by their artistic beauty than the actual scientific information they contained, though of course the latter is the reason for their existence. You might be fooled into thinking I am talking about a palaeo artist here, but in fact Helmut’s work is photographic, and more importantly he does not work in natural light, but in the world of ultraviolet.
Helmut’s pictures if you have seen them are immediately obvious as they are typically in vivid shades of blue, yellow or green and highlight beautifully both bones (or shells) and especially soft tissues like pterosaur wings, feathers, muscles and more. Most recently he provided the images for the description of Juravenator, but before that has photographed almost every specimen of Archaeopteryx, numerous pterosaurs (including the Dark Wing and new Anurognathus) and many, many other fossils from the Solnhofen beds of his native Bavaria. If you have Dave Unwin’s recent book on pterosaurs, or Luis Chaippe’s recent one on birds you will certainly have come across his work.
You have probably missed Helmut’s work because although he is often credited for his photos and appears as an author on plenty of papers (in addition to authoring his own) mostly he writes in German and the papers are directed to German journals. However, such has been his contribution to palaeontology that he was recently deservedly awarded an honorary PhD from the University of Munich. Part of my reason for doing this piece is to promote his work as it is not as widely known or appreciated as it should be – there are important things hidden in UV light that researchers and preparators alike need to be aware of.
Helmut has been called the ‘King of UV’ by several of his friends and while this is meant as a good-natured joke, it is also true. It has been known for over a century that many fossils fluoresce under ultraviolet light and that especially soft tissues can look very different to the background matrix in some cases. However, with low powered lights and primitive photographic techniques and taphonomy still in its infancy, it was more of a curio than a useful scientific method. UV continued to be used over the years with techniques improving, but little ever entered the literature and so it is hard to tell exactly what it brought if anything to the palaeo table. You could maybe tell there was something there, but with no detail and no effective way of capturing it on film. [Photo of Helmut (2nd L) courtesy Markus Moser].
As you can see through, things have certainly changed and Helmut is responsible for pretty much everything that has been produced in the last ten years or so. The equipment he uses is either custom made or built by him himself (in the case of his filters) so its not like people can just replicate his work – the act of setting the lights, filters, exposure times and more is every bit as much and art as a science and experience is key. Each piece of rock and bone or tissue will react differently to different light wavelengths and will be captured differently with varying exposures and filters. The right combination is needed to show up whatever you are interested in and multiple frames are needed to capture all of the available details.
Lots of different things show up (of course depending on the preservation) in UV and more importantly look very different that under natural light. While the photos are beautiful in themselves, the technique can be used to show up bony sutures that are otherwise hidden, and especially to separate bones or softs from the underlying matrix or each other. Often the two can barely be told apart they are coloured so differently, but when one shows up blue and the other white, life becomes much easier! The work on the dark wing Rhamphorhynchus wing tissues was greatly facilitated by photos that could separate the blood vessels from the muscles tissues because they showed up in different colours with the right filters. Chitin and calcerous carapces do not escape either, and plenty has been done on the invertebrate fossils of the Solnhofen too and shown up new features, or cleared up confusions. Invisible tissues and patterns can even be revealed as tissue soaks into the matrix. The rock might not loo and different in shape or structure, but under UV the clear outlines of scales can appear, traces of lost feathers or skin that remain present but hidden. Sadly what is often revealed is that material probably was present but invisible to the naked eye was prepped away to reach the bones (just look at what happened to the Berlin Archaeopteryx when they knew!).
That is lost forever now, and while much new work in Germany is at least being done in conjunction with UV light in order to search for and preserve soft tissues, the same is sadly not the case in other places. If was for this reason that Xu Xing and I (together with Zhou Zhong-he and Zhang Fu-cheng) brought Helmut to Beijing this year. You can imagine my reasoning – if soft tissues have been happily prepared away on all kinds of pterosaurs and others in the Solnhofen, what might be happening with the Jehol fossils? Might critical stuff be being destroyed, and might many new features remain hidden in those that have already been studied.
Helmut spent many long and dark hours in the IVPP basement setting up his travel kit and shooting all kinds of fossils looking for traces of hidden structures, lost parts and new information as well as trying to tease his filters and lights into showing up what might just be there. For the answers to those questions you will have to wait for us to start the work or writing up the results, but from that you should be able to work out that his trip was not wasted.
While the skills and equipment necessary for this kind of work are obviously highly specialised (not to mention the patience where each frame might need an hour long exposure) and not cheap to acquire (either in costs or actual time and effort devoted to it) this really is a technique that needs to be pushed hard. Palaeontology is more than just bones, but as Helmut’s work reveals, much of the stuff beyond bones is either invisible, or in the past was erased before we even had a chance to find it. Hopefully this post has gone a very small way to promoting not just his work, but more importantly his methods.
One final note, all of the photos here are ‘on loan’ so to speak and belong to Helmut, please don’t go copying them, downloading them or linking to them without permission. I don’t have access to software to protect or watermark them, so I’m relying on people being nice and reading this.
Dave Hone's Archosaur Musings 
Is that a photo at the top, of the Rhamphorhynchus specimen which demonstrates that pterosaurs do have a trailing edge tendon?
It is one of them, yes. However the term ‘trailing edge tendon’ is highly loaded and there has been a great deal of discussion about waht that actually is. It would be a subject for a good post at soem point, though I’ll have to ask Helmut for permission to use his other photos. The consensus seems to be that it is an organic structure but what? A thickening of the wing, a fold in the trailing edge, just an extra bundle of actinofibrils, some muscle tissue, or somethincg close to a genuine tendon / ligament? No one can really confirm or deny any of these with great confidence and in fact there are good reasons for thinking there isn’t a tendon. That’s about it really.
It occurs to me that if something remains to fluoresce, perhaps it would be worthwhile to take small samples of the matrix surrounding fossil bones and chemically analyze them. If it works for ancient “traces of life” compounds in rock 4B+ years old, it should work for flesh made rock.
I guess it might, though I’d have to aska geochemist – I guess there are all kinds of factors at play here – chemical compsiiton of the rocks, types of analyses, types of preservation. The obvious problem I can see is how you tell what you have found belongs to the animla next to it. That is, jsut becuase you get a positive result, how do you know those chemicals came from the animal that left the bones and not bacreria in the water, or a dead leaf that was not preserved, or who knows what? It might be good to tell organis from inorganic, but probaly not ‘bird organic’ from ‘leaf organic’.
Beautiful images! I’m watching the Daily Planet clip of you and Helmut in Beijing (taped Monday Jan. 13). Thank human goodness for people who’ll take this kind of care.