OK so last week Darren and I asked for questions about the preparation process and the Gorgosaurus project. Obviously Darren has way more knowledge and experience than me and is a researcher in his own right, but hopefully I can chip in on a few of these as well from the other side of things and my own experiences.
For those who are a bit late to the party, this is also an opportunity to round-up what’s been going on. Essentially Darren Tanke, a fossil preparator at the Royal Tyrell Museum in Canada is giving a blow-by-blow account and photo journal of his work on a new Gorgosaurus specimen. This started as a jacket of plaster collected in the field and Darren has been peeling away the rock to reveal the tyrannosaur entombed inside.
If you want to see how we got to where we are then you’ll want to see (deep breath): The introduction to Darren and Gorgosaurus, then Part 1, Part 2, Part 3, Part 4, Part 5, Part 6, Part 7, Part 8 and Part 9 and now here we are at the Q & A and prelude to, well Part X. Now onto the questions and our answers:
How does the preparator judge the quality of the bone? E.g. “the bone in the pelvic region appears to be very soft and crumbly” from above, is that based on visual observation, carefully try & error, something else?
DH: For me it’s always been simple observation. You can generally see cracks and breaks and the condition of elements around them and thus what to expect. Occasionally you have what appears to be perfect bone with something broken underneath and that can be a pain, but if you go slowly you’ll discover it before it becomes a major issue or any irreparable damage is done.
DT: It is a bit of visual observation and then more diagnosis during actual preparation. Some bones appear to be in great condition on the outside yet are in terrible condition internally. I have even seen the reverse, where a hollow inside the bone filled with sediment which then turned very hard yet the bone did not. Bones can be good on one end and bad on the other. Whatever the case, all efforts are made to make the bone good again for research and/or display.
What “apprenticeship” would someone interested in being a fossil preparator serve? Would you normally undertake a course and then follow that up with “work experience” at a museum?
DT: There is really no course you can take to learn how to prepare fossils, though it is my understanding the Denver Museum of Natural History had/has some certifcation course for volunteers they have preparing dinosaur fossils. In my experience learning how to prepare fossils is at best a “learn as you go” proposition. I started early on my own, doing mechanical preparation (electric engraving tool and hammer with chisel/awl) by age 12 and chemical (vinegar on limestone fossils) by age 13. Completely prepared vertebrate fossils I did when I was 16 look similar to what I produce now. Learning how to prepare fossils at “School A” may not be entirely useful at “Museum B” as the rock type and the fossils themselves differ at different locations. This has happened to me several times where I went into the field with another museum to do fieldwork and preparation work, only to find I had to retrain myself there. As for apprenticing I would say start as a volunteer first (this is what I did), learn the ropes and prove your worth. Preparation involves a lot of common sense and patience.
DH: I do know of some preparators who are happy to take on willing volunteers and show them the ropes. While I was a PhD student at the time, I got my training this way and was allowed to practice on some non-valuable material and outcasts before tacking some proper material. I’m no preparator, but as a research it is very useful to know how the fossils are prepared. If I’m working with a preparator to get something done, then know the limits of the rocks and bones and how longs things will take is great and when making jackets in the field these can be tailored to make preparation easier etc.
What sort of specimens are museums willing to let inexperienced preparators cut their teeth on?
DT: Typically we would start people on easy projects and/or ones where the specimen is not that important if it gets damaged or destroyed. Obviously we would not let a new person work on a dinosaur skull. Part of one maybe but not a whole one. They get lots of training and supervision at first then we slowly wean them off of that as tnhey gain confidence and experience, though they are encouraged to ask questions at anytime and undergo spot checks to seeing how they are doing.
Finally, did you have a mentor who taught you a lot of the tips and tricks or are they mostly things that you have found out for yourself (say, after a specimen crumbled to dust)?
DT: I did not have a specific mentor. Mosty of the things I knew about fossil preparation I brought to Philip Currie’s team in 1979, so I “hit the ground running” so to say. I am of course still interested in learning new tricks or products that are useful for specimen preparation.
But I am more generally curious… the internet is abuzz with activity as a response to the accessibility of research papers and researchers… ie. dinomailinglist, blogs, open publications, etc. How much affect is there on the community of preparators? Are amateurs welcome in the way that they are in conceptual research? Is there active outreach education towards places like China, where I’ve heard preparation hasn’t got as much history?
DH: From my experiences in China there’s not really any formal, organized outreach (at least in part due the language barrier). But preparators do regularly go there as part of expeditions or research teams and I know of Chinese preparators who have served in institutes in the US and Europe for stints. So ideas and methods do definitely get exchanged, if at a lower rate than say between North America and Europe.
DT: There is, I believe an Internet group for preparators, called PrepList or something like that. Also a Preparators Session at annual Society of Vertebrate Paleontology meetings. We do sometimes exchange technicians, though certainly way more come to us than us going there. We have had preparators from Argentina, China, Australia and several European countries. We tend not to have much contact with amateurs in our province when it comes to preparation. This is likely due to laws that say fossils cannot be “modified” after collection, and this includes preparation. We do get probably a dozen calls a year from people across North America wanting preparation tips on things they have found.
Why is the fossilised femur hollow? Is this how they are usually found? Does all of the internal gunk get eaten/rot away, and only the bone itself becomes mineralised?
DH: Well femora are generally hollow as they house a large marrow cavity that makes blood cells, though they can be pneumatic too and have air-sacs extending into them in some cases. But closer to what you are asking, yes the marrow will rot away leaving the femur as just a tube. If this happens to fill in with sediment (say it got broken a little and sand or dirt could get in) then this will fossilise too and give some real support to the bones and they can keep their original shape much better, as of course do solid bones. Those which are not filled in (and this is a huge problem for pterosaur bones which are highly pneumatic and have very thin walls too) can collapse and get crushed by the weight of rocks above them during fossilisation.
You’ve found a femur and fibula but what makes you certain that the tibia will also be there? Are the two bones (tib/fib) fused together and, if so, would this likely be an adaption for weight-bearing?
DH: They are not fused into a unit (not in tyrannosaurs anyway) but it’s reasonable to expect the tibia to be there. Few if any of the major elements have moved from their original positions and so with the lower leg and foot and the upper leg and pelvis all there, it’s very unlikely that the whole of the tibia has gone out of the middle of this lot without any signs of decay, dismemberment or whatever.