Why, hello dear readers! Welcome to a fun new segment of Rex Machina I’m calling Nick’s Paleo Adventures.
I thought this new series of blogs might be a fun and interesting thing to try out. Paleontology isn’t just something we discuss and argue about and hypothesize over; it’s also a lived experience. I want to see more of that human aspect, and I think the best way to see it is to create it.
I can think of no better experience to start this new blog series off with than my recent tour of the Gray Fossil Site back in June 2019. It was an incredible and intimate experience of a dazzling paleontological site led by two fantastic and generous paleo educators. I’ll probably say it over and over again in this blog, but I’m so grateful for their time and patience. I will truly never forget it.
A Touch of Gray’s History
Before we dive in to the tour, you probably know what I’m about to do: some background. I’m big on context and history, so let’s talk about the Gray Fossil Site a bit–how it formed, how it was found, and what scientists there are up to today.
Somewhere between 4.7 to 7 million years ago (Mya), a pond formed in the middle of a forested area. Worn away by groundwater, the limestone bedrock in this region of late Miocene/early Pliocene Tennessee collapsed. This limestone bowl was fairly deep, and likely had a cliff-face on one side. It eventually filled with water and became a pond.
This new pond quickly became an important resource for local flora and fauna. Several different animal species lived in or near this body of water, and used it regularly. There were reptiles such as snakes, turtles, and alligators; various different species of fish; flying animals like birds and bats; and mammals whose size ran the gamut from rodent to mastodon. Many different types of plants called the pond home as well, including bald cypress, multiple species of grapevine, other flowering plants, and tree species such as oak, hickory, and pine.
This eastern Tennessee pond was a haven for the plants and animals that lived there. It was also an incredibly ideal environment for fossil preservation. It was a relatively calm body of water, and the deposition of carbon-rich, dark clay and a wealth of decaying plant material helped preserve many organisms’ remains.
Eventually, the pond filled up, and the burgeoning ecosystem around it went away. Left behind was an incredible paleontological site, teeming with hundreds of specimens that would shed light on the recent geologic past. But until recently we never knew it was there. In fact, we nearly destroyed this paleontological gem by accident.
A Gray Discovery
It was the year 2000. The Tennessee Department of Transportation (TDOT) and their contractors were hard at work. TDOT had initiated a project to widen and straighten State Route 75. This required a fair amount of excavation. In May of that year, the road crew was widening a section of SR-75 in Gray, TN when they started noticing some odd geology; the dark clays they were unearthing were unfamiliar to everyone on site. Nobody recognized what they were digging up, so Larry Bolt–one of TDOT’s geologists–took samples to the Tennessee Geological Survey for analysis.
TDOT briefly halted the excavation work, and brought in scientists to explore the site. Within minutes, they were pulling bones out of the clay. Many of the initial discoveries turned out to be tapir remains. However, they excavated tusk fragments of a mastodon, reptile fossils, and other important finds as well. The scientists were under pressure to pull up as much as they could quickly; excavation was only temporarily stopped. However, it became clear as more material was pulled up that something remarkable was lurking beneath all that clay.
Thankfully, the right people were paying attention. Former Tennessee Governor Don Sundquist recognized the significance of the finds in Gray. He soon ordered SR-75 rerouted around the fossil site. Then, in 2002, he announced TDOT was awarding a grant of $8 million to Eastern Tennessee State University (ETSU)–now in charge of the site–to build a visitor’s center. Thanks to Sundquist’s foresight, they were able to preserve a truly remarkable piece of natural history for excavation and discovery.
Gray Today
The Gray Fossil Site has become a busy paleontological operation since its discovery almost 20 years ago. Around 100 species of animals have been identified, as well as countless flora specimens. However, despite this labor, only about one percent of the site has been excavated. ETSU still manages the site today, and students, professors, staff, and volunteers work there year-round.
Teams limit excavation to the warmer months, but lab work is nearly continuous. They need to sort, catalog, identify, and preserve countless specimens. There are a good number of large fauna discovered at Gray, but the majority of fossil material is on the smaller side. Collecting and sorting through this material is labor-intensive, so the labs are never short of work.
Several important finds have been made at Gray that have changed perceptions about the Miocene/Pliocene epochs of North America. For example, the discovery of an extinct species of red panda–an animal only known to Asia today–changes their distribution on the continent. The only other known American red panda comes from Washington State, and is only known from a single tooth. The preservation of near-complete red panda specimens at Gray provides much finer detail into what this group was doing in the Americas and for how long.
Another significant find–due to the sheer frequency of specimens–is tapirs. Over 100 individual tapir specimens have been identified at Gray since paleontologists first started digging. We find the majority of extant tapir species in Central and South America, and we know them to have originated there around 50 Mya. The incredible number of specimens found at Gray can help paleontologists dive further into the lives of these animals. They’re also shedding light on the environment and ecosystem of this prehistoric pond.
Seeing the Gray Fossil Site
This past June, I went on vacation in Tennessee with my family. I contacted David Moscato, Educator at the Gray Fossil Site and co-host of the Common Descent Podcast (one of the absolute best podcasts out there; go support them on Patreon–I do!) and set up a tour of the Gray Fossil Site as part of our trip. Needless to say, I was very excited.
Now, I had anticipated David would be the only one leading the tour. His co-host on Common Descent, Will Harris, was in Florida as far as I knew. So imagine my utter surprise, excitement, and wonderment when I walked in the door and found both of them there! As a super-fan of Common Descent (and that one guy who emails and messages them way too much) I was tickled pink. I could not believe we were about to get a tour from both of these guys.
And oh, what a tour they gave us.
We started out with a quick look at some specimens. A few were 3D printed, including a red panda skull and a turtle shell. We also got to take a look at some actual tapir material as well. Meanwhile, David and Will gave us an overview of the site and the species that once lived there.
Next we headed out to see some of the digging locations. There’s such a wealth of specimens, flora and fauna alike, that the excavation teams can’t treat it like other digs. Will explained how they have to excavate less than an inch down at a time and sweep all the clay into buckets. They then put the clay into bags and store it until screening can be done.
Screening involves the use of crates lined with fine mesh on the inside. Teams fill the crates with clay from the bags, submerge them in solution, and wash away as much extraneous material as possible. Screens with leftover material are set out to dry in the open air. Later, the teams bring them into the lab for sorting.
David and Will identified two sites for us that had yielded important finds: the Rhino Pit and the Mastodon Pit. The Rhino Pit contained two incredibly well-preserved specimens of a new species of rhinoceros, Teleoceras aepysoma. At the other pit, teams unearthed the remains of multiple mastodons. Rather than being the typical fragmentary remains found elsewhere, these specimens are far more complete, which is very exciting. Some folks at ETSU have even discussed the possibility of the animals being a transitional form, but this idea needs more research.
After seeing the pits, we headed over into the lab. We saw how staff and volunteers use microscopes to sort through smaller material, and how they clean and handle larger specimens. David and Will also showed us the novel approaches their teams are taking to reconstruct fossil materials.
Finally, we explored the collections room and what happens with the sorted fossil material. We got to meet some of the folks working on identifying and studying the fossils, as well as the collections manager. We got to see and (carefully) touch the tusks of “Big Boy,” one of the two T. aepysoma specimens. As well, we got some looks at a couple of turtles, the lower jaw of one of the mastodons, some alligator remains, and of course some more tapirs. The researchers even let us take a look at what they were identifying under the microscope, including some plant remains.
Touring the Gray Fossil Site was such an incredible experience. Not only did we get a fantastic surprise tour by both Will and David, but I walked away with a much deeper appreciation of paleontology and the Neogene. Admittedly, I favor Mesozoic fauna–dinosaurs in particular. However, I think that’s due to a lack of understanding of what came before and after. I walked away from that tour with so many more questions and visions of the Cenozoic that I need to find answers for now. So stay tuned, because I imagine you’ll be finding some non-dinosaur content on Rex Machina in the near future…
Thank you to David Moscato and Will Harris of the Common Descent Podcast for the incredible tour of the Gray Fossil Site. Really, you don’t know how much it means to me.
You can find David, Will, and the podcast on Twitter respectively at: @DMos150, @WillHHarr, and @CommonDescentPC. You can also go like the Common Descent Facebook page!
Listen to the Common Descent Podcast on Podbean, iTunes, YouTube, or other podcast players you like. You can support Common Descent and get special content from the show through Patreon.
The Gray Fossil Site can be found on Twitter @GrayFossilSite and their website. You can also subscribe to A Touch of Gray, a podcast all about the people, stories, and events of the Gray Fossil Site.
It was our pleasure to show you around, Nick!
By the way, your recollection is mostly correct! That is indeed a piece of tapir femur you’re holding, and that first pit is the Mastodon Pit. The second pit photo is the Mulch Pit (a much less memorable name).
-David