A paleo preparator among us
Museum staffer readies prehistoric fossilsfor exhibition

By D. Lyn Hunter, Public Affairs

Jane Mason, a senior museum preparator with the Museum of Paleontology, dusts a crocodile fossil as she prepares it for exhibition. Noah Berger photo

04 April 2001 | With the precision of a jeweler and the patience of Job, Jane Mason slowly picks at the hunk of matrix that lays before her — carefully removing one grain of sand at a time.

After months of painstaking work, using tiny brushes, needles and hooks, the treasure beneath the crud is finally revealed: the skull of a prehistoric crocodile that lived more than 64 million years ago.

As a preparator for Berkeley’s Museum of Paleontology, Mason cleans and repairs fossils — some more than 200 million years old — for research and exhibits.

A measured pace
While speed is an attribute in today’s society, it is a sin in Mason’s lab, where preparing a single fossil can take up to 8 months.

“Some people consider this work tedious, but I find it contemplative,” said Mason, wrapped in a smock stained with the paint, chemicals and epoxies that are tools of her trade. “I’m used to working at this pace.”

She has spent the last six months on the crocodile specimen, a Leidyosuchus found last summer in a former Montana creek bed. Mason figures the skull needs two more months of work.

Her measured pace is crucial to preserving the delicate fossils. If she is too aggressive, the petrified bones — survivors of multiple millennia — can, within seconds, crumble to pieces in her hands.

Patience is important not only for protection, but also for discovery, she adds.

“While working on the Leidyosuchus, I found several small, round concretions in its mouth,” explained Mason, who called in a paleobotanist to examine the specimens. “They were natural casts of ancient figs that washed down stream and lodged in the croc’s snout.”

On rare occasions, Mason, while picking away at a fossil, hits upon bone that hasn’t petrified. “Touching something that old, in its original state, is such a kick,” she said.

Stages of preparation
The fossils come from digs conducted each summer by Berkeley paleontologists and their students. They enclose their finds in crude plaster field jackets, which are delivered to Mason at the end of the season.

With an electric cast cutter, just like the ones used by medical doctors, she carefully slices through the plaster, never sure what she’ll discover inside.

“Sometimes I see a pile of dirt,” Mason said, “and others times, lovely, recognizable pieces of fossilized bone.”

Each fossil is unique, said Mason, presenting a different set of challenges. Variances can exist even within the same fossil, especially if one end was exposed to the elements while the other was protected by layers of earth.

Because of the bones’ fragile condition, Mason uses a variety of methods to support them while she is cleaning them. For the Leidyosuchus, she is using Popsicle sticks embedded in a special water-soluble blue wax.

Her lab is littered with found objects — cigar boxes, coffee cups, scrap pieces of wood — used at various stages of preparation or storage.

The tools used are determined by a fossil’s condition and proportion, which may range from the thumbnail-sized skull of a tiny opossum ancestor — which Mason cleans under a microscope — to a 10-foot-long skull of a primeval whale.

Once the cleaning is finished, Mason draws on a number of additional skills, such as painting, woodworking, welding and sculpture, to ready an item for viewing. When the specimen is complete, she makes copies by constructing molds and creating casts. These lightweight, durable and exact replicas are shipped to scientists around the world so they can share in the museum’s discoveries.

Trial by tedium
A trained artist and science enthusiast, Mason fell into this line of work after a visit to the American Museum of History in New York.

“They had the most dynamic and engaging displays,” recalled Mason. “I thought creating those kinds of exhibits would be the perfect way to combine my interests.”

She worked as a museum volunteer, hoping it would develop into a full-time job. The curators tested Mason by assigning her the most tedious jobs, like mounting small teeth on the heads of pins. She survived these trials and was eventually hired for a special project. When that ended several years later, she found her way to Berkeley, where she continues to indulge her passion for the prehistoric.

Though she spends her days delving deep into the Earth’s past, it is the future that guides Mason’s work.

“I try to think of the people who many years from now will be studying or admiring these fossils,” she said. “How I handle these pieces determines what information will be passed on for generations to come.”