Jul

Verrry slooow work for extremely patient people

Lynn Russo uses an air scribe to remove rock from a fossil brontothere skull. Brontotheres were rhinoceros-like relatives of horses and tapirs that became extinct about 35 million years ago. This fossil was found in South Dakota.

Volunteers are important members of the Department of Paleobiology at the National Museum of Natural History, assisting staff with everything from making digital scans of old field notebooks and slides to helping prepare fossils for scientific study. Lynn Russo spends many of her Mondays in FossiLab, our exhibit fossil preparation laboratory, removing rock that encases the fossil skull of a large extinct mammal called a brontothere. Specially trained in fossil preparation techniques, Lynn has been at work on this project for more than two years, with only occasional help from other volunteers. Her progress is captured in this short video made from a series of still photos of the skull.

“It takes that long?” Visitors to FossiLab often ask why it is taking Lynn so long to uncover the skull. Each fossil preparation project presents a unique set of challenges, but Lynn must grapple both with the similar appearance of the bone and rock matrix, which are almost the same color, and with the fact that the hard surface of the bone was roughly abraded by sediment before it was preserved, exposing the softer, spongy interior in places. So not only is it hard to tell the rock that must be removed from the bone embedded in it, but it also is very difficult to remove the matrix without damaging the fossil.

Much of the time, Lynn uses a jackhammer-like air scribe to chip away at the rock, but when she works near the spongy areas of the bone, she switches to a gentler tool—basically a large needle—to scrape the rock away, bit by bit. She applies adhesives to the bone as she uncovers it to prevent it from falling apart, and she brushes water onto the specimen as she works because the wet bone and matrix reflect light differently, making it easier to tell them apart.

Progress on the brontothere skull is very slow, but that is the nature of fossil work. The giant Diplodocus in the neighboring Dinosaur Hall, collected in 1924 by Charles W. Gilmore, arrived at the Museum, he wrote, as “26 tons of rock-enclosed bone.” This extraordinary skeleton required 2,545 working days to excavate, prepare and mount. Compared to that job, Lynn has it pretty easy!

Charles W. Gilmore wrote of the Diplodocus, shown here newly mounted in the Dinosaur Hall in the 1930s, “The magnitude of the task… of preparing one of these huge skeletons for public exhibition can be fully appreciated only by those who have passed through such an experience.”

A version of this post was originally published by the blog, Digging the Fossil Record: Paleobiology at the Smithsonian. You can read more about the interesting history of the FossiLab brontothere on the National Museum of Natural History Unearthed blog, and more about the work in FossiLab on the FossiLab website.

Gilmore’s 1932 article on the Diplodocus skeleton is available as a Biodiversity Heritage Library scan. His 1942 accounting of time spent preparing the Diplodocus for exhibit is on page 342 of this scan of his History of the Division of Vertebrate Paleontology in the United States National Museum.