Recently, I had the exciting opportunity to prepare some material from the Gobi of Mongolia. One of the specimens was a tiny lizard, some of the smallest bones measuring in at about a millimeter. While this specimen proved to be quite a technical challenge, one of the more difficult decisions came after the prep was finished. The small block was being worked on at the Field Museum, and I had to figure out how to get it back home safely to New York, and the AMNH. |
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The bones had been left in situ, both to preserve their orientation, and because trying to separate the fragile elements most likely would have resulted in their destruction. One option for transport would have been imobilizing the block in a bed of Ethafoam, being careful not to let anything contact the bones. I didn't feel comfortable with that method, as I felt that any vibration or shocking had the potential to do considerable damage. Normally, I would use Carbowax (Polyethylene glycol) to in-fill the void space and provide support. In this case however, the methods for removing the Carbowax could have been equally destructive. A new product had recently shown up in the lab though, and proved to save the day.
If you aren't already familiar with Cyclododecane from the past two SVP meetings, it is quite a useful compound. It comes complete with a fairly low melting temperature, as well as the seemingly magical ability to completely sublimate at room temperature, negating any tricky issues relating to removal. Just be aware that health effects have not been adequetely studied. Work under a fume hood, or with otherwise exceptional ventilation. For application in small amounts, I use a pen designed for melting wax, basically just a wire element hooked up to 2 AA batteries. This allows for precise deposits of CDD, otherwise, heating a quantity over a hotplate works as well.
Going back to the little lizard, I first pooled CDD under the elements that were self supported, namely the limbs. As you can see in the above photo, the femur, tib/fib, humerus, and radius/ulna have all been thoroughly cleaned, and are only anchored at the ends of the bones. After providing a CDD base for these bones, the rest of the skeleton was covered in a thin coat. At this point, I switched to Carbowax to add another, thicker layer of protection. My reasoning was twofold. First, I wanted to prevent exposure of the CDD, in case the specimen couldn't be unpacked right away. I didn't want sublimation to take place while still in the packing material, and wasn't sure quite how quickly that would happen. Alternatively, I didn't want sublimation to take too long once the little guy was unpacked. In order to facilitate easy removal, I pigmented the Carbowax so that the two materials were easily distiguishable. Then, the block was packed in an ethafoam lined cardboard box, and hand carried on a plane back to the American Museum. |
