For all the work that goes into getting fossil plants back to the Museum, that's only the first part of their journey. The next step is to prepare the fossils for further research.

Once in the Museum, fossils are unwrapped and placed in flats (shallow boxes). During this process, Leaf Whackers and Museum staff double check each fossil for the locality number applied in the field.

Dr. Kirk Johnson, the DMNS paleobotany curator, looks over the fossils and decides which ones should be prepared in the fossil lab. Most of the time, this simply involves deciding how much matrix should be removed, but it can also mean deciding which fossil plants can be sacrificed. Leaves can be deposited in dense layers, and sometimes an interesting plant is partially covered by another plant. Kirk makes the call on what to keep and what to remove, and marks the areas to be removed for the preparators.

Prepared leaves: Click to enlarge
Fossil leaves after preparation
Ideally, leaf preparation is done under the microscope. Fossil leaves are sometimes faint so magnification makes them much easier to see. The most frequently used prep tool is an air scribe, essentially a tiny jackhammer with a pounding tip and a steady stream of air to blow away debris. Preparators use two different air scribes: delicate AERO® scribes and heavy-duty Chicago® scribes. Which air scribe is better depends on the fossil, the matrix, and the preparator's preference. Leaf Whackers usually work all at once on special leaf preparation nights, and set the fossil lab humming with noisy scribes. They usually kick up a lot of dust, too, which is mitigated by an even noisier ventilation system.

How is preparing fossil plants different from preparing fossil bones?

  • Plant preparation typically takes less time. Preparation of a fossil vertebrate can consume tens or even hundreds of hours. While some plant preparation jobs also require many hours, fossil plants can usually be prepared in a matter of minutes — sometimes even seconds.
  • Preparators working on vertebrate fossils point the air scribe toward the bone so that the matrix flakes away just above the bone layer. Leaf Whackers do the same thing, unless the leaf still has a cuticle. The air from a scribe can easily blow away the delicate cuticle, so in that instance, the Leaf Whacker aims away from the leaf.
  • As in the field, Leaf Whackers avoid using solidifying agents such as vinyl acetate. While very useful for fossil bones, these substances can obscure the venation pattern in a fossil leaf. Using glue to fix broken fossils, however, is okay.

No one knows exactly what's hiding under the matrix, so preparators must keep their eyes open for unexpected shapes. Sometimes a simple looking leaf has an unusually long drip tip or even a stem attachment. Occasionally an even more interesting leaf is buried in the rock. For this reason, fossil leaves are prepared with an air scribe and handed over to Kirk for inspection before they're trimmed.

Trimming fossil leaves requires a special tool that chops off the excess rock. Some Leaf Whackers consider trimming their favorite job because it gives them a chance to see every fossil. Fossils can easily break in this process so the trimmer keeps glue handy.

By the end of the leaf preparation evening, the fossil lab has gotten pretty messy. Just like preschoolers after arts and crafts, Leaf Whackers pitch in to clean up the mess. Meanwhile, the newly prepared fossils are taken to the collections area where they're individually boxed and placed in Museum storage cabinets. Curation is the next step.


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