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The Looy Lab paleo detectives

Solving the mysteries of the past and present one rock at a time

East of the Berkeley campus, we see the beautiful, green Berkeley Hills, the golden letter "C" and a somewhat classy-looking, dome-shaped building on the Lawrence Berkeley National Laboratory campus. This houses the ALS, or Advanced Light Source. Personally, I find the name a bit silly because it doesn't seem to capture the awesomeness of this giant machine. It's like calling the Space Shuttle a Progressive Flying Tool.

synchotron at LBL

Photo from newscenter.lbl.gov

The ALS is a synchrotron, a particular type of particle accelerator. The particles are sped up by a shifting magnetic field within a closed circuit. The shape of this circuit is an almost circular polygon and since the building was specifically designed for the synchrotron, the building is round. But what happens inside?

Each time when the particle beam is bent at each of the polygon's corners, light is produced — primarily ultraviolet and x-rays. The x-rays are not your ordinary dental office x-rays, but much "harder" x-rays. Unlike the relatively harmless photo at the tooth doctor, this beam would kill you before you could say "¿qué?"

But what can paleontologists and paleobotanists do with this advanced light? Hard x-rays allow us to see fossils while they are still inside the rock. This means that you don't have to crack open the rocks, clear away rock matrix and run the risk of damaging precious fossils. In some cases, the material is simply too fragile to be prepared; it would not hold up. Scanning the rock allows us to make 3D reconstructions of fossils hidden inside the rock without damaging them.

We've been scanning all kinds of really old fossils: horsetails from the Carboniferous (~300 million years ago, or Ma), kelp holdfasts from the Oligocene (~30 Ma), tiny (3 mm or ~1/8 inch) and not so tiny (7 cm or ~2¾ inch) pine cones, early land plants from the Devonian (~390 Ma), and pollen cones of extinct redwoods from the Cretaceous (~70 Ma). The size of the fossils is limited by the size of the protective shielding enclosure that keeps the scientists safe while using these lethal x-rays.

Because the cyclotron basically runs 24/7, the scanning time slots are generally 24 hours long and scanning rocks can take a while. Here's the general process that we go through for each scan:

Cindy and Ivo

Left: First, we select a fossil. Right: Then we mount it on a stand (improvising a la MacGyver). These and the rest of the photos are by Cindy Looy and Dori Lynne Contreras.

Orienting a fossil on the stand

Next we orient the fossil on the stand just right to get the best quality scan of the target specimen (which surprisingly takes a bit of work and "expert guess-timation").

The hutch

Once ready, the mount and fossil are placed in a "hutch" made of radiation shielding. Left: This is the hutch, a big container that protects everyone around from the harmful x-rays. Right: Inside the hutch there is a normal optical camera (at ~9 o'clock), the stand on which the fossil is mounted, and the x-ray detector (the big black box at the right).

The hutch doors and camera

To start the scanning process a number of safety procedures have to be followed, otherwise the beamline will not open. Left: The doors of the hutch have to be closed, and while an ominous alarm sounds, you have to press certain buttons to actually allow the x-ray to come into the hutch. Once it does, a red rotating emergency light comes on and the doors cannot be opened. Right: Once the sample is in the hutch we use the normal camera to focus in on the sample.

Adjusting the settings and set to go

Left: As each fossil sample is different, adjustments to the settings are needed. For instance, thicker rocks generally need a higher dose of x-rays than thin ones. Right: And we are good to go! It's scanning time!

Waiting for the scan to finish

And then, we wait …

Data analysis and celebration

Left: Actually, there is not a whole lot of sitting about going on, because the data that the x-ray collector gathers has to be analyzed. This takes up quite a bit of time (note the ridiculous amount of caffeine) and a LOT of computing power. Luckily, the computers at Lawrence Berkeley National Lab are up to the task! Right: Then we celebrate our success!