Under the grass, gravel, soil and sand lies layers of rock containing a record of past life. In North America, paleontologists have been studying this record for over 150 years. Many of the fossils they unearthed were stored in the United States Geological Survey’s (USGS) Denver Fossil Collection.
“The collection holds specimens that were used to build our understanding of North American geology,” said Kathy Hollis, the collections manager for the National Fossil Collection at the Smithsonian’s National Museum of Natural History.
Earlier this year, the last of the USGS collection's 1.2 million fossils arrived at the museum, completing an acquisition that began back in 2018. But the acquisition was only one step in a bigger plan to systematize and digitize the USGS fossils for scientists everywhere to access for research.
"We now have the capacity, the technology and the big picture vision of how to get this collection organized. What might have been aspirational ten years ago, we’re actually doing now,” said Hollis.
Using mollusks as geologic markers
Some of the fossils are large, like dinosaur bones and mammal skeletons. Others are smaller in stature but just as scientifically valuable, like ammonites — a taxonomic class of ancient marine mollusks that help paleontologists date layers in the fossil record.
Dating geologic layers using fossils is called biostratigraphy. Ammonites are crucial in biostratigraphy, because they existed for so long and their species’ evolution can be tracked through rock layers. For example, if an ammonite species lived during a specific age and is found in a rock layer, paleontologists know that layer falls within a certain time frame. They can use that comparative technique to date different rock’s layers.
“Rock layers, and therefore, the fossil record is patchy,” said Hollis. “Ammonites can help us connect those patchy records to each other so we can understand how ancient landscapes and oceans have changed over millennia.”
Since the 1800s, scientists have been adding ammonites to the USGS collection and using these fossils as geologic markers to improve their chronological understanding of past life.
“Without these ammonites, we wouldn’t be able to understand what was going on in North America millions of years ago,” said Hollis.
Turning trinkets to data
Like their ammonite counterparts, other USGS specimens also hold information about ancient North America. But that information is only helpful if it’s easily accessible.
“Researchers throughout the centuries have used different ways to organize things in the collection. Without unifying all their methods, we just have a collection of trinkets,” said Hollis. “So, we want to standardize everything into one comprehensive dataset.”
Digitization is a key part of the museum’s plan for standardization. In addition to photographing specimens, digitization also means uploading original notes from the fossils’ discovery and other archival materials into the National Fossil Collection’s online database.
“Digitization is any aspect of creating digital data about something. We do everything from standard imaging of original labels to transcription of other archival materials and documenting the three-dimensional specimens,” said Holly Little, the paleobiology informatics manager at the museum who is processing the collection.
Sometimes the process involves a bit of detective work. The locations where fossils were collected in the 1800s may not have the same name as they did a century ago. Or the paleontologist collecting them might not have recorded longitude and latitude as accurately as it can be recorded today.
"The notes might describe a place that no longer exists or has a different name now,” said Little. “But we have to do our best to figure out where that was, because — in paleontology — the point in the ground where an object came out of is essential information.”
By combing through the archival material associated with each specimen, Little and Hollis can deduce where the fossils were found. Finding those present-day locations ties into the museum’s push to standardize the USGS specimens.
“We’re trying to gather as much of the core information we have as possible, so that we can explain what these fossils are and where they came from,” said Little.
A final resting place
After it’s processed, the USGS collection will remain in the museum’s National Fossil Collection with around 40 million other fossils. The collection’s rehoming represents a longstanding relationship between the museum and the USGS that started back in the late 1800s.
“We’ve always had some of the USGS collection,” said Little. “Now, the vast majority of it will be at Smithsonian including all of those valuable archival resources.”
Soon researchers will be able to access the digitized specimens and all their accompanying materials to learn more about North America’s prehistoric biodiversity and geography.
“In a very basic sense, this is about making the collection discoverable,” said Hollis.
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