Usually, fossil preparation takes place behind the scenes.
Inside the Fossil Lab, intrepid paleontologists work on fossils that they find just yards away in the asphalt.
This is the real thing — paleontological lab work — up close and personal!
Paleontology in Action
The Fossil Lab is a busy, glass-walled paleontological laboratory in the center of the Museum that offers visitors an exceptional opportunity to witness how Ice Age fossils are cleaned, studied, and prepared for exhibit. Assisted by skilled volunteers, a team of paleontologists are currently working on specimens from Project 23, a rich deposit that has yielded a cornucopia of Ice Age fossils from animals including extinct saber-toothed cats and mammoths that were entrapped in the asphalt in the Los Angeles Basin between 40,000 and 10,000 years ago.
Once the fossils are carefully carted inside, paleontologists open the plaster jackets that have contained fossils of prehistoric dire wolves, lizards, pigeons, hawks, and rabbits as well as the bones of “Zed,” a near-complete Columbian mammoth. The Fossil Lab, open seven days a week, is evidence that the Museum is a bustling research institution and a place of unparalleled discovery with an excavation site that is not in some foreign locale, but in its own backyard. Visitors often have a visceral sense that they are treading the same ground that the animals in front of them — now on raised platforms and mounted behind glass — placed their prehistoric footprints.
Cleaning Up. When a fossil first arrives in the Fossil Lab, the first step in its preparation is cleaning. Volunteers use a solvent (n-propyl bromide) to dissolve the hardened asphalt from the bones, allowing them to carefully clean the remaining matrix (sediment) off the bone. Dental picks are sometimes used to dislodge particularly stubborn grains of sediment. Larger fossils, and fossils with many cavities such as skulls and vertebrae, can sometimes take several days or even weeks to clean completely. Very delicate specimens — for instance, skulls with intact sinus cavities or very fragile bird bones — are soaked in solvent overnight to prevent breaking. After the bone is clean, its matrix is placed into a jar of solvent to soak for at least a week. The matrix will eventually be rinsed and sorted through for microfossils. The bone itself is left out to dry for several days, and then polished. Every fossil from Rancho La Brea retains its unmistakable brown hue even after cleaning.
Microfossils sorting. After the matrix surrounding each fossil has soaked in solvent for several days, it is rinsed through a mesh screen and set out to dry. It is then dry sifted through another screen to eliminate fine-grained clay, which is unlikely to produce fossils. However, small intact samples are sometimes set aside for ultra-microfossil sorting at a later date. Volunteers will peer through large magnifying glasses and sort through the matrix, grain by grain, looking for the remains of plants, insects, ostracods (tiny freshwater crustaceans), shells and tiny bones. Though microfossil sorting is the last step in fossil preparation, it is the first thing new volunteers do when they start work in our lab.
Keeping track. After a fossil has been cleaned and its entire matrix has been sorted, it is time to give everything a number. This system of cataloging all the fossils ensures that their data — where the fossils came from and their correct identifications — are permanently retained. At first, all the specimens are captured in a paper catalog and later entered into an electronic database.
Fossil Lab Volunteers
Lab volunteers do the majority of day-to-day preparation of fossils excavated from the localities within the park. Currently there are more than 65 volunteers, ranging in age between 18 and 90. Between them, the volunteers contribute an average total of 200 hours per week to lab projects. Volunteer excavators are famously devoted. They receive preliminary training in the Fossil Lab, learning about the Pleistocene flora and fauna and the techniques necessary to prepare asphaltic fossils. After completing 96 hours in the lab, approved volunteers have the opportunity to roll up their sleeves and dig outside. This extremely demanding and meticulous work is an honor for the volunteers, many of whom boast of having returned to excavate for over a dozen years. It’s also a long-standing tradition that excavators provide nicknames for the fossils that they work on.