A digital dino bone

This post is a re-blog, or more accurately the English translation re-blog (with minor alterations to adapt it to pre-existing content here on dinosaurpalaeo), of a post I wrote for the Museum für Naturkunde Berlin‘s blog Museumsdinge. The title roughly translates to “museum things/objects/topics” – as often, there is no one-on-one corresponding translation between German and English.

The bone in the image below is nothing extraordinary, really, at least not in a natural history museum. The left thighbone of a dinosaur – so what’s special so about it?Still, this is no ordinary dinosaur! And what is that red stuff on it?

You won’t find this dinosaur in a lot of museums. First of all, because the dinosaur in question, Kentrosaurus aethiopicus Hennig, 1915, isn’t present in many collections. Only in the Museum für Naturkunde Berlin and the Palaeontology department and museum, Institute for Geosciences, Eberhard-Karls-University Tuebingen (homepage) can you see a Kentrosaurus.

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Excursus: What’s it with the tapeworm name “Kentrosaurus aethiopicus“? And “Hennig, 1915”? The former is the genus and species name. Kentrosaurus roughly means “spiky reptile”. Aethiopicus sounds like Ethiopia, butere should rather be understood to indicate a more general African origin. Now, laypeople are used to a dinosaur having one name, and one name only. That’s how it usually is in movies and documentaries, and often also in the press. Only famous “T. rex” is an exception. Experts, however, shudder at “Trex” or, heaven forbid, “T-Rex”! Strictly speaking, each dinosaur has a double name. First comes the genus, spelled with an initial capital. In our example that’s Kentrosaurus. Genus names are given only once (or, more exactly, once each for plants and animals), so confusion is impossible. You can give a genus name alone, but it then means all the potentially quite many species that belong to that genus and are, so to speak, sibling or sister species. The genus Canis, for example, comprises dogs and wolves and jackals and much more. The genus is followed by the species, which is not capitalized and never used without the genus name in front. Species epithets can only be given once in a genus, but the same species epithet can be used in many genera. Here, the species is “aethiopicus“, and in order not to have to vagabond around all alone, causing confusion, it must always be used in the combination “Kentrosaurus aethiopicus”. If it is obvious which genus you’re talking about you are allowed to abbreviate the genus, as long as you give a species name: K. aethiopicus. And this is where “T-rex” stems from, or whichever maligned form you see. “T” is for Tyrannosaurus, and the species is Tyrannosaurus rex, or, for the lazy of mouth or pen, T. rex (no other spelling allowed!). This system was thought up by a certain Mr. Linnaeus, and opinions on how great an idea that was are somewhat divided.
By the way, scientists always put genus and species in italic type, so that one can spot immediately that it is a genus or species name you’re dealing with, and not some other, normal term. Not really that imporant anymore, with English having become the standard language of science. But imagine a Latin text with Latin species names in it – italics help a lot in that case.

So, back to our Kentrosaurus! What’s this Hennig guy doing there, and why are there 1915 of him? There aren’t – it’s simply the name of the author who first described Kentrosaurus and named it. Edwin Hennig took part, as a employee of the Museum für Naturkunde Berlin, in the famous excavations at the Tendaguru hill in Tanzania during which the wonderful dinosaurs in the MfN were found. And 1915 is the year in which Hennig’s description of Kentrosaurus was published. And it’s all part of the complete scientific name!

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OK, our bone has a name now, but why is Kentrosaurus only to be found in Berlin and Tübingen? That’s because the genus is known only from Tendaguru, and except for Berlin only the NHM London has excavated there – and they… erhm, let me put it this way: they pretty much made a mess of it. In any case, there are no Kentrosaurus bones in the London collection, as far as anyone knows.  The Tübingen skeleton stems from the Berlin dig. When he moved to Tübingen to become professor Hennig himself organized the transfer. Logically, he didn’t want to leave his beloved baby all alone in far away Berlin 😉 Thus, from isolated elements a second skeleton was built and mounted in Tübingen.

So here we have an African dinosaur that, except for a souvenir of Hennig’s to Tübingen, is exclusively MfN. But even in the exhibition and collection of the Museum für Naturkunde a visitor cannot see what the image above shows. It doesn’t show a real bone, a physical object, at all, but a three-dimensional digital representation. A virtual bone, if you perfer. I had it calculated from 150 photographs. That’s called photogrammetry, and as you surely know my blog is full of posts on the topic: how you do it and what you can do with the resulting files.

Soon, we’re going to host a conference at the MfN called DigitalSpecimen 2014 (meeting homepage) that will deal exclusively with method for creating such 3D models and managing 3D data sensibly. I believe this to be a very gripping topic, and about 100 of my colleagues from many different professions (among them archaeology, art history, architecture, mechanical engineering, palaeontology and zoology) think so, too – and will attend. For such a special and narrow topic that’s quite a crowd!

On the image above a keen-eyes observer will notice, aside from the red stuff, that there is a number on the bone. Below you can see it in more detail. “MB.R.3583” it says, and below  “Tendaguru, St”. Tendaguru is rather self-explanatory, the locality. MB is for Museum Berlin, R for Reptilia. Then, there’s four digits – that’s how the collection numbers for fossil reptiles are structured. And St is for place of discovery pit St, thus called by Hennig because it was choke full of stegosaur bones. Tendaguru pits were numbered with letters, and the bones in them with Arabic numbers, so that nothing could get mixed up (which invariable happened a few times anyway).

 

I’ve also added a photo of the real bone, with tape measure, so that you can see how big it really is – and how good and high-resolution the 3D-model came out! And that there is no red stuff in reality. Also, there’s a view of the mounted skeleton in our exhibition. What a spiny beast! I’ll have something to post on that, soon.

The close-up view of the collection numebr shows two more things of interest: a hole in the bone and a small sticker inscribed X1. The hole was caused by a coring. That means drilling a small cylinder out of the bone shaft, which is then made into think sections. Using a microscope you can then study the bone structure and gain information on the speed of growth and the age of the animal. My colleague Ragna Redelstorff and others have done exactly that (Link to the scientific paper; sadly not OpenAccess) and found that the animal was rather small, of reproductive age and fully grown.The small sticker with the X and the number is one of many that I placed for digitizing. The bone must be photographed from both sides, and the markers help stitching the models of both halves into one.

Soon, I’ll have more to say about Kentrosaurus and what makes it special. What, there’s something else still? Oh, right, the red stuff…… well, that secret I’ll reveal in November at the Annual Meeting of the Society of Vertebrate Paleontology (meeting homepage). This year, it’s in Berlin, hosted by the Museum für Naturkunde.On the museum blog within the frame of #FossilFriday and also on Twitter (hashtag #SVP2014) there will be a lot to read about it. And – promise! – the answer to the red stuff riddle 🙂