All of the fossils that we work on in FossiLab are real, as are most of the fossils in the halls that surround the lab. A few complete replicas are on exhibit, however, including the Camptosaurus and the T. rex. You can tell the replicas because they are labeled as “casts.”

Why do we exhibit casts? Some fossils are extremely fragile, and all are subject to damage by vibration and changes in temperature and humidity. Because the rarest and most historically important of our fossils are irreplaceable, we exhibit casts of these, storing the real fossils under more controlled conditions that preserve them for future research.

Visitors with eagle eyes will notice that many of the real fossil mounts include some bones that are casts. Few skeletons are found 100% complete, but by including replicas of the missing bones, we can give visitors a good sense of what the ancient animals looked like. A good example is the Teleoceras, an extinct North American rhinoceros, exhibited near the FossiLab door in the 'Mammals in the Limelight' hall. This skeleton is composed of both fossil and sculpted material. Note that most of the ribs are fragmentary, with plaster filling in for missing bone. Another example is the Giant Ground Sloth in the 'Ice Age' exhibit. In the photo you can see that missing portions of the lower jaw and cheek bones were sculpted in plaster when this fossil was mounted for exhibit.

Historically, it was common for museums to mix and match bones from different individuals in order to create complete mounted skeletons. Unfortunately, the bones weren't always well matched in size, and this could introduce inaccuracies into the way the mounts were positioned. Today, paleontologists agree that proportionally accurate casts of skeletons give a better impression of reality than chimeras pieced together from actual fossils. The video adjacent to the Triceratops skeleton shows how this mount was updated with casts to meet this new standard.

Plaster replaces the pieces missing from many of these Teleoceras ribs. Click to zoom.

It is easy to see the plaster mandible (lower jaw) and cheek bones in the giant ground sloth mount. Click to zoom.

Scientists in the Department of Paleobiology travel to field sites in the United States and around the world to search for fossils. They ship many of the fossils they collect to FossiLab, where we prepare them for study. Most of the current FossiLab projects are fossil discoveries from the U.S., but we are also preparing fossils collected in Zimbabwe, in Africa, and we recently completed work on several fossils from South America.

Sometimes, we also work on fossils from the basement. Like many other large museums, the National Museum of Natural History has unprepared fossils in its collections. Some of the fossils were judged by earlier generations of preparators to be too difficult to prepare, and were set aside to await improvements in tools or techniques. Others were collected, even though no one was available to prepare or study them, because leaving them in the ground would have ensured their destruction by erosion or human activities. Our work on these "basement treasures" makes the fossils available for study by scientists who may not have been born when the fossils were collected!

Curator Kay Behrensmeyer's field crew excavating vertebrate fossils in northern Arizona in 2012. Click to zoom.

Some of these unprepared fossils in our basement storage area will come to FossiLab for preparation. Click to zoom.

Scientists can learn the age of rocks using an accurate and reliable method called radiometric dating, which compares the observed abundance of naturally-occurring isotopes and their decay products. Used in tandem with traditional geologic principles, such as the principle of superposition, the numerical age of virtually any rock formation, and by extension, any included fossils, can be determined. Visitors to FossiLab will find more information about dating methods at the base of the Tower of Time near the entrance to the Dinosaur Hall. Online resources are available on the Department of Paleobiology website. Follow this link and click the yellow "Dating Methods" tab at the bottom of the web page.

The Department of Paleobiology's website on geologic time. The red oval highlights the tab for accessing more detailed information about dating methods. Click to zoom.

The amount of time it takes to prepare a fossil varies depending on the size and complexity of the specimen as well as the nature of the rock matrix that encases it. A small specimen such as a leaf might be uncovered in only an hour or two, but a large, complicated skeleton encased in very hard stone might require a few years of painstaking work.  All of the work in FossiLab is done by volunteers who have received special training and work in the lab part time.

A block of rock containing a brontothere skull, as it appeared the day we started work. The skull is upside down and the brown upper teeth are partly visible. Click to zoom.

Two years later, the protruding cheekbones have been uncovered on the left and right, more teeth are visible, and the upper jaw bone is partly exposed below the teeth. Bone toward the back of the skull has been uncovered in many places. Click to zoom.

A fossil leaf is partly visible at the bottom of this block of rock. The rock is marked with black ink in the area where the rock is to be removed. Click to zoom.

It took several hours of work with an air scribe to remove the rock matrix that partially covered this leaf. Click to zoom.

Visitors to FossiLab often comment on the red sand that we use to support fossils during gluing and storage jacket construction. It is garnet, a mineral known by most people as a lovely red gemstone. Crushed garnet has many industrial uses, including as an abrasive in sandblasting, but we use it in our sandboxes because, unlike beach sand, it does not contain fine silica dust which can cause lung disease when breathed.

The broken mandible (lower jaw) of a Palaeosyops, a type of brontothere, is set upright in garnet sand during gluing. Click to zoom.

If you are in high school or younger, take lots of science and math in school and work hard to get good grades. Work on your reading and writing skills so that later on you will be able to communicate your ideas and research discoveries clearly to others. Start to learn about fossils and how to find and identify them by joining a local fossil or geology club and going on collecting trips. Consider becoming a junior member of professional organizations such as the Society for Vertebrate Paleontology. In college, study as much biology and geology as you can. Gain more experience (and perspective on paleontology careers) by volunteering to assist researchers in their labs or in the field. It is likely that you will need to earn a Masters or PhD degree in geology or paleontology if you want to pursue paleontology professionally, but if that is not a possibility you still can contribute to the field. Self-educated amateur paleontologists have made many important discoveries and collaborated with university and museum scientists to write papers and publish in scientific journals.

It is a baby Compsognathus, a small carnivorous theropod that lived during the Late Jurassic.

This fanciful image drawn by paleoartist Mary Parrish shows a preparator using a pin vise and carbide needle to remove rock matrix covering the bones of the animal's right leg and tail. The middle section of the dinosaur is show partially "reconstructed" with a life-like arrangement of muscles covering the bones. At the front end, the reconstruction has been completed by the addition of skin and very fine, hair-like feathers. You can learn more about creating life-like images of dinosaurs by visiting the Reconstructing Extinct Animals page of the Smithsonian's Dinosaurs in Our Backyard website.

Click to zoom.